Friday, December 11, 2020

Rats fed tasty but unhealthy food products that people eat (e.g. hot dogs, muffins); did not reduce junk food intake in the presence of cues that predicted shocks, demonstrating the high rewarding level of junk food

The Cafeteria Diet: a standardized protocol and its effects on behavior. Jaume F. Lalanza, Eelke M.S. Snoeren. Neuroscience & Biobehavioral Reviews, December 10 2020. https://doi.org/10.1016/j.neubiorev.2020.11.003

Rolf Degen's take: https://twitter.com/DegenRolf/status/1337087523336712195

Highlights

• Cafeteria (CAF) diet has high construct validity.

• CAF diet induces hyperphagia and metabolic syndrome better than other diets.

• A CAF protocol should include different nutrients, tastes, textures, etc.

• A CAF protocol should rotate and be voluntary.

• CAF diet alters reward preferences and tends to reduce stress and spatial memory.

Abstract: Obesity is a major health risk, with junk food consumption playing a central role in weight gain, because of its high palatability and high-energy nutrients. The Cafeteria (CAF) diet model for animal experiments consists of the same tasty but unhealthy food products that people eat (e.g. hot dogs and muffins), and considers variety, novelty and secondary food features, such as smell and texture. This model, therefore, mimics human eating patterns better than other models. In this paper, we systematically review studies that have used a CAF diet in behavioral experiments and propose a standardized CAF diet protocol. The proposed diet is ad libitum and voluntary; combines different textures, nutrients and tastes, including salty and sweet products; and it is rotated and varied. Our summary of the behavioral effects of CAF diet show that it alters meal patterns, reduces the hedonic value of other rewards, and tends to reduce stress and spatial memory. So far, no clear effects of CAF diet were found on locomotor activity, impulsivity, coping and social behavior.

Keywords: Cafeteria DietWestern DietJunk FoodObesityAnimal ModelSystematic ReviewFood PreferenceStressMemoryReward System


4.6. Mood: Anxiety- and Depression-like Behaviors

Food and mood are closely related. While stress in some cases induces a reduction in the amount of food consumed, in others, stress increases eating, and often the eating of highly palatable food. This phenomenon is colloquially referred to as eating “comfort food”, and it applies to both humans and rodents (Dallman et al., 2003Pecoraro et al., 2004). Comfort food can be defined as food that is eaten as an attempt to reduce anxiety and for its well-being effects rather than its nutritional value, owing to humans and other animals obtaining pleasure due to emotional relief (Dallman, 2010Dallman et al., 2003).

Consistently, stress is considered a risk factor for obesity (Sinha and Jastreboff, 2013), and epidemiological and longitudinal studies have found a bidirectional relationship between mood disorders and obesity (Gariepy et al., 2010Luppino et al., 2010). A recent meta-analysis found that the prevalence of anxiety and depressive symptoms were significantly higher in overweight and obese children and adolescents than in the non-overweight/obese (Wang et al., 2019). This comorbidity is, however, not fully understood yet and it could be strongly affected by genetic predisposition and environmental factors (Mansur et al., 2015).

If there is a causal relationship between junk food and mood in humans, one would expect that exposure to the CAF diet should also affect anxiety- and depression-like behaviors in rodents. Regarding gestational designs, only a few studies assessed the effects of dams receiving CAF diet on stress responses in their pups. Superficially, these studies seem to have reported opposing effects – two studies finding reduced anxiety levels in pups fed a CAF diet in the open field (Speight et al., 2017Wright et al., 2011a), while a third study found a decrease in the amount of time spent in the center, suggesting an increase in anxiety (Ramírez-López et al., 2016). However, a more detailed examination of the methods employed appear to offer an explanation of the differences observed. Specifically, the studies differed in how strongly the open field environment in which anxiety-related behavior was illuminated – light levels being a key determinant of how anxiogenic the environment is. Hence, Wright et al. and Speight et al., used high (i.e. strongly anxiogenic) levels of illumination above the test set-up (130 and 70 lux, respectively) compared to Ramírez-López et al. (30 lux). Illumination in an open arena could be a critical factor for the visual system and as discussed before, albino rats may experience more disturbances than pigmented strains. Nevertheless, all these three studies used the same albino strain Wistar, so the strain does not seem the cause of this discrepancy. Therefore, we hypothesize that the low illumination was insufficient to induce significant anxiety, at least in the open field test.

Regarding tests of anxiety-related behavior in the elevated plus maze, the lack of effects seen in the study by Speight et al, can be explained at least by the age at testing, since they looked at rats on PND23, 2 days after weaning, while the rats in the other studies were tested 9-10 weeks after weaning (Ramírez-López et al., 2016Wright et al., 2011a). Ramírez-López et al. (2016) saw increased levels of anxiety-like behavior in the elevated plus maze, whereas Wright et al. (2011a) found the decreased levels in the same test in males. It should be noted though that Wright et al. (2011a) compared pre-gestational, gestational and lactation periods, and the reductions in anxiety were not generalized to all experimental groups.

Finally, increased levels of anxiety-like behaviors were also seen in the light-dark test, as mice pups from dams on a CAF diet entered the dark (and less anxiogenic) compartment faster and more often from the light (and more anxiogenic) compartment (Ribeiro et al., 2018).

Therefore, indirect CAF diet exposure via their mothers may result in both an increase and a reduction in anxiety-related behavior. As mentioned before, pups showed more anxiety when their dams were fed CAF diet in some studies (Ramírez-López et al., 2016Ribeiro et al., 2018), however these studies administered a little varied CAF diet compared to the studies that found reduced anxiety-like behavior. In addition, it is possible that increased stress levels in pups were not produced directly by gestational CAF diet exposure but by abnormal maternal care, because the CAF diet can alter maternal care behaviors (Ribeiro et al., 2018Speight et al., 2017) (see Social Behavior section below). Therefore, after considering these methodological differences, we tentatively conclude that indirect CAF diet exposure via their mothers may result in a reduction in anxiety-related behavior, even though more studies are required in order to further validate this conclusion.

In classical design studies, where subjects were fed CAF diet themselves, the effects of this diet on behavioral and neurophysiological measures of anxiety levels also remain unclear. When we look at effects in male rats and mice, four studies found reduced anxiety levels, in either the open field or elevated plus maze test (de Oliveira et al., 2019Lalanza et al., 2014Leffa et al., 2015Pini et al., 2017), while four studies found no changes in anxiety (Beilharz et al., 2018Ferreira et al., 2018Sack et al., 2017), or an increase upon CAF diet consumption (Ferreira et al., 2018Warneke et al., 2014). Again, all studies conducted with rats chose an albino strain (Wistar or Sprague-Dawley), so the albinism of the animals cannot explain these differences. In female rats, two studies found a reduction in anxiety levels (Lalanza et al., 2014Warneke et al., 2014) with more pronounced effects in adult females (Warneke et al., 2014), while two studies found no changes (Cigarroa et al., 2016da Costa Estrela et al., 2015). Since illumination levels during behavioral tests were not properly reported in most of these classical studies, we cannot determine whether this might have contributed to the different findings. Social isolation is neither an alternative factor, as single and grouped-housing protocols are found in both outcomes. It is, thus, difficult to draw any conclusions on whether CAF diet has an effect on anxiety.

Interestingly, CAF diet exposure shortly after weaning did not, at first, reduce anxiety in the elevated plus maze and in the light/dark test, but it did significantly attenuate the anxiogenic effect of maternal separation (Maniam and Morris, 2010a). Attenuating effects on stress levels due to maternal separation were also seen in the dams (Maniam and Morris, 2010b). These results might suggest that CAF diet, and junk food in general, exerts significant anxiolytic effects in stressed subjects.

The hypothesis of junk food consumption reducing stress is supported by the effects of the CAF diet on neurophysiological measures. Maniam and Morris (2010a, 2010b) also found that a CAF diet reduced the expression of glucocorticoid receptors (GR) and corticotropin-releasing hormone (CRH) after maternal and litter separation. Similarly, the CAF diet also reduced ACTH (adrenocorticotropic hormone) and corticosterone after chronic stress exposure (Gustaityte et al., 2019Zeeni et al., 2015bZeeni et al., 2013) and CAF diet in rats reduced adrenal gland weight gain following restrain stress (Macedo et al., 2015). Finally, it was also shown that switching from STD chow to CAF diet exposure reduced corticosterone levels after restraint-induced stress (South et al., 2012) and also reduced amygdala GR receptors mRNA expression compared to chronic (15 weeks) CAF diet (Martire et al., 2014).

Overall, we conclude that CAF diet consumption can attenuate stress responses. This clear effect of a CAF diet on the neurophysiology of stress is not a surprise, given that the neural circuits mediating stress responses, reward processing and those regulating feeding behavior and metabolism are intimately connected (for a review, Meye and Adan, 2014Rabasa and Dickson, 2016Sinha, 2018). There is overlap and mutual influence between these systems, for instance, the paraventricular nucleus of the hypothalamus is a hub connecting feeding and stress by regulating food intake and activation of the HPA axis, these actions being sensitive to both glucocorticoids and insulin (for a review, Koob and Schulkin, 2019Morris et al., 2015).

The association between CAF diet consumption and depression-like behaviors has also been assessed. In male rats, it was shown that a fixed CAF diet does not induce depression-like behavior as assayed by the forced swim test and the sucrose preference test (Ferreira et al., 2018Macedo et al., 2015). In male mice, though, a rotated CAF diet reduced immobility time in both the forced swim and the tail suspension test, suggesting a reduction of certain aspects of depressive-like behavior (Leffa et al., 2015). This latter finding is in line with the observation of increased levels of the neurotrophins BNDF (brain-derived neurotrophic factor) and NGF (nerve growth factor) in the hippocampus, both which are considered as anti-depression markers (for a review, Björkholm and Monteggia, 2016).

In female rats, a rotated CAF diet has also been shown to reduce some signs of depression-like behavior in the forced swim test (Maniam and Morris, 2010b). These results highlight the importance of considering both the specie – mouse is not a small rat – and the sex of experimental subjects, especially when studying mood disorders which display pronounced sex biases (for a review, Altemus et al., 2014).

Interestingly, in male rats exposed to stressors (either maternal and litter separation or chronic variable stress), the CAF diet compared to STD chow reduced depression-like behaviors (Maniam and Morris, 2010a2010b;) and tend to reduce them (Zeeni et al., 2013). This would suggest that a CAF diet exerts its antidepressant effects on animals already suffering from a mood disorder, as we noted in the stress sub-section. On the other hand, however, da Costa Estrela et al. (2015) found the opposite effect, whereby the CAF diet reduced the climbing time in the forced swim test (climbing is considered a non-depressive-like behavior) in female rats previously exposed to restraint-induced stress. However, in the STD chow group, the restraint-induced stress did not induce the expected depression-like behaviors, which might indicate that animals were, indeed, not depressed.

To conclude, the CAF diet has been shown to have anxiolytic and antidepressant-like effects on animals that were placed in higher stressful states. For non-stressed animals, the effects of a CAF diet on anxiety and depression have been less clear, but there seems to be a trend towards an anxiolytic effect overall (Table 4). Thus, the idea of eating junk food as a comfort food to relieve negative mood states may be valid. Nevertheless, more research is needed for a better understanding of the bidirectional relationship between junk food eating and negative mood states.

4.7. Coping Behavior

The aforementioned behavioral tests, such as the elevated plus maze, light/dark test and the forced swim test are all assays based on unconditioned responses, and are said to involve passive responses. That is, there is not an active solution for the animals to take in order to avoid the stressor (Bourin et al., 2007). The elevated plus maze, for example, has a safe zone, the closed arms, and there is no need for the animal to move to the rest of the maze beyond its natural instinct to explore. So, the animal can avoid the stressful situation passively. The same principle applies to the forced swim test, where there is not an active approach that would be beneficial to the rodent. In the real world, however, rodents and humans face complex problems that can usually be solved with active, complex and brave actions. For example, giving a speech as introvert is a hard situation that requires an active confrontation with one’s own fears. In other words, one needs to cope with it.

Two studies have investigated the effect of the CAF diet on this kind of coping behavior in rodents. Mucellini et al. (2019) used the step-down inhibitory avoidance task to study the effects of gestational exposure at puberty and adult age, while Cigarroa et al. (2016) used the two-way avoidance task in a classical design.

The step-down inhibitory avoidance task consists of an arena with a glass platform elevated above the floor. This platform triggers an anxiety-like response in rats. Consequently, the natural urge is to leave the platform and return to the floor. However, since the floor is electrified, the rat has to fight against its fear of highness in order to avoid the electroshock. The latency to get down is therefore a measure of aversive memory or coping. Compared with a more passive light-dark test with the absence of punishment for entering the comfortable zone, this inhibitory avoidance test requires a coping strategy from the animal. As we have discussed, the CAF diet has no effects on locomotor activity, which could impair a coping response due to excessive or deficit motion. On the other hand, CAF tended to reduce stress, mainly in stressed animals, so CAF diet could be beneficial for facing stressful situations calmly. However, CAF diet did not affect coping in the gestational study and reduced coping in the classical study. Methodological differences in both studies might explain these distinct results.

It was found that exposure to CAF diet did not affect coping behavior in step-down inhibitory avoidance task. The latency to get down significantly increased from training to test session, which means that rats learned to cope with the fear of heights. However, this effect was found in both STD chow and CAF diet groups at both ages, puberty and adulthood (Mucellini et al., 2019). Therefore, indirect CAF diet exposure does not affect coping behavior in rats.

Cigarroa et al. (2016) tested adolescent female rats that were directly exposed to a CAF diet in the two-way avoidance task. This task makes use of a fear-mediated conflict between a tendency to freeze and a tendency to escape from an electroshock. The box is composed of two compartments separated by an open door. In order to escape or avoid the upcoming foot shock, signaled by a light and/or a tone, the animal must learn to change between the two compartments. So, when the light/tone signals the incoming electroshock, the animal should come back to the compartment where previously the animal received an electroshock. As there is not a safe compartment, the animal has to face its fears of returning to the compartment where it previously received a punishment in order to avoid the following electroshock (Lalanza et al., 2015). Interestingly, and different from the absence of gestational effects, when female rats were exposed to the CAF diet directly, they displayed impaired coping behavior. CAF diet fed rats had a smaller decrease in the number of avoidances and a smaller increase in the escape latencies.

Two studies are not enough to draw general conclusions, but they indicate that a CAF diet does not improve coping behavior and one suggests it may do the contrary. The differences found between the gestational and the classical study could simply be caused by the timing of CAF diet exposure, but the sex of the subjects could also have played a role, because the gestational study looked at male offspring, while the classical study examined females. Future studies will have to shine more light on this topic.

4.8. Cognition and Memory

Human studies suggest that diets rich in fat and sugar are a risk factor for cognitive impairment in adults, for increasing vulnerability to dementia and, even, for slowing the development of children’s cognitive skills (Davidson et al., 2019Morris et al., 2015). Consistently, similar impairment effects were also found in rodents exposed to HF/HS diets (Cordner and Tamashiro, 2015). Therefore, it is expected that the CAF diet will impair cognitive function. Memory could be investigated with different approaches. In this review, based on the types of behavioral tests used, we differentiate between spatial and contextual memory, recognition memory and executive function.

In gestational studies, to the best of our knowledge, the only assay so far deployed has been the object recognition test. It was found that indirect CAF diet exposure via their dams reduced recognition memory in female pups, although for male pups this impairment was less robust (Moreton et al., 2019Mucellini et al., 2019Wright et al., 2014). There is a need for more studies that further characterize these sex differences, and we strongly encourage researchers to go deeper into the question of how perinatal exposure to a CAF diet might affect the cognitive abilities of offspring.

In classical studies, the CAF diet has been found to impair spatial and contextual memory, but no effects on recognition memory or executive function have been observed. Spatial memory is a hippocampus-dependent memory that relies on remembering a location with the help of environmental cues. In three studies that assessed spatial memory in the Morris water maze, two found that the CAF diet reduced spatial memory (Ferreira et al., 2018Lewis et al., 2019), whereas the other found no effect compared to STD chow and HF/HS diets (Pini et al., 2017). However, this apparent discrepancy might be explained by methodological differences. Pini et al. (2017) applied a shorter and more intense learning phase (2 days, 12 trials per day) in the Morris water maze, compared to the standard procedure of 4 to 6 days with only 4 to 5 trials per day (Bromley-Brits et al., 2011Vorhees and Williams, 2006). Furthermore, in that study, the CAF diet did not induce obesity indicating that their CAF diet protocol was not an effective obesogenic model, maybe because CAF diet was limited only for one-hour a day. In addition, the rats were single-housed while were grouped in the first studies (Ferreira et al., 2018Lewis et al., 2019). Spatial memory can also be assessed by the Barnes maze, which is a less stressful version of the Morris water maze, without water. Interestingly, the CAF diet did not affect spatial memory in such a Barnes maze, but as the authors reported, this lack of effect could be explained by the lower levels of stress. It is known that stress can reduce the motivation to learn, which could then explain the differences in results between the Barnes and Morris water mazes (Gomez-Smith et al., 2016). All of these studies were carried out with albino strains, what could have interfered with rat’s performance in visuo-behavioral measurements like the Barnes and Morris water mazes (Prusky et al., 2002). Further studies using pigmented strains will confirm the detrimental effects of CAF diet on spatial memory without the inconveniences of visual acuity.

The CAF diet also reduced contextual memory as assessed by both the object recognition test and the fear conditioning test (Beilharz et al., 20162014Reichelt et al., 2015). Interestingly, these behavioral tests are able to assess different types of memories depending on the exact protocol used. In the object recognition test, for example, one can assess contextual memory by changing the positions of the objects instead of the objects themselves. Applying this paradigm, it was found that consuming a CAF diet reduced the time spent exploring the object placed in a new position (Beilharz et al., 20162014), Thus, and similar to the Morris water maze, animals fed with the CAF diet did not distinguish between different locations. In another experiment, the same researchers surprisingly found no effects of CAF diet on contextual memory compared to STD chow using the same protocol for the object recognition test. However, and like the previous studies, the exploration ratio between the old and the new position was very close to 50% in the CAF group, which indicates low levels of contextual memory. The exploration ratio indicates the amount of time spent exploring the two different objects or positions, so a ratio of 50% means that both objects/positions were explored a similar amount of time, without preferences for the new one. Interestingly, when the CAF diet was combined with probiotics (evidence suggests that the gut-brain axis and the microbiota could affect the central nervous system), the exploration time of the object placed in the new position actually increased (Beilharz et al., 2018). This interaction between CAF diet and probiotics suggests that CAF diet could have reduced the exploration time of the object in the new position even though the comparison with the STD chow group did not reach significance.

The fear conditioning test can be used to assess recognition memory with an associative learning paradigm or contextual memory, using a contextual learning paradigm. One study found that the CAF diet impaired contextual memory in the fear conditioning test, as shown by CAF diet-fed rats displaying reduced freezing, compared to STD chow controls, in the context associated with the electroshock (Reichelt et al., 2015). However, a second study found no effects of a CAF diet in the contextual version of the fear conditioning test (Ferreira et al., 2018). However, in this second case, only the training context without the conditioned stimulus was used to test contextual memory, which could explain the lack of significant difference between the diet groups.

More consistently, the CAF diet has not been found to impair recognition memory using the “new object” version of the object recognition or the associative learning paradigm of the fear conditioning test in multiple studies (Beilharz et al., 20182016, 2014; Ferreira et al., 2018Leffa et al., 2015Reichelt et al., 2015). Surprisingly, in a study comparing two CAF diet groups, one with free-access to cola-based soft drink and another with orange-based soft drink, opposite effects were found on recognition memory (Feijó et al., 2019). While the CAF + cola group increased the time exploring the new object, the CAF + orange reduced it compared to the control group. However, the soft drink groups were not compared to each other and the control group was different for the CAF + cola and CAF + orange. Therefore, this result must be taken carefully and does not represent a clear evidence of CAF diet impairing recognition memory.

Finally, executive function was only tested in one study using a puzzle box test, which consists of a subdivided arena with different obstacles to make progress more difficult (e.g. an underpass filled with sawdust) that change each trial. The animal needs to overcome the obstacles to leave the anxiogenic compartment and get into the small and covered safe compartment. The general analysis of the puzzle box, based on the latency to reach the save compartment, showed that executive function was not affected by the CAF diet, even though increased CA1-CA3 volume (Sack et al., 2017).

At a neurophysiological level, the hippocampus is a logical candidate for the impairment of spatial and/or contextual memory caused by the CAF diet, since this brain region also regulates eating behavior (Davidson et al., 2019). It has been shown that a CAF diet increases neuroinflammation and reduces neurogenesis in the hippocampus, which, in most of the studies, correlated with a spatial/contextual memory impairment at a behavioral level (Beilharz et al., 20162014Ferreira et al., 2018Gomez-Smith et al., 2016Reichelt et al., 2015). Interestingly, a gestational study did not found impairment of maternal CAF diet on pups, but neither effects on hippocampal BNDF (Mucellini et al., 2019). Similar results regarding impairment of spatial memory and disruption of the hippocampal formation have also been found with HF/HS diets (Boitard et al., 2014Molteni et al., 2002Stranahan et al., 2008).

In aggregate, we conclude that direct exposure to a CAF diet seems to be a risk factor for spatial and contextual memory deficits, while indirect exposure via dams may impair recognition memory, which was not affected by direct exposure to CAF diet in classical studies. Although preliminary studies indicate a potential role for changes to the hippocampus in mediating these cognitive declines (Table 4), further work is needed to more fully reveal the brain mechanisms underlying the changes in spatial/contextual and recognition memory produced by a junk food diet.

4.9. Social behavior

The concept of social behavior is complex and it includes many types of interactions, including behaviors such as social approach, social play behavior, sexual behavior, and maternal care. A few of the studies we reviewed tested the effects of the CAF diet on some of these social behaviors.

Sexual behavior is itself a multifaceted social behavior (for a review of sexual behaviors, Heijkoop et al. (2018)) consisting of numerous behavioral components that are under regulated by complex hormonal systems, including the estrous cycle. High-fat diets and obesity are able to affect reproductive functions, and obesity is a risk factor for infertility in both women and men (Broughton and Moley, 2017Kahn and Brannigan, 2017). Therefore, it is possible that the CAF diet also affects sexual behavior.

In female rats it was indeed found that eating a CAF diet affected the estrous cycle: the CAF diet reducing ovulation rates and release of luteinizing hormone, while also increasing the frequency of the diestrus phase and the release of prolactin (Sagae et al., 2012). Interestingly, however, these changes to the estrous cycle did not have consequences for sexual behavior itself, the CAF diet not altering sexual paracopulatory or receptive behaviors, i.e. hops, darts, ear wiggling, solicitations and lordosis.

The effects of the CAF diet on male sexual behavior, on the other hand, have only been investigated in a gestational study. This study showed that CAF exposure altered male rat sexual behavior with less intromission behavior. This change in behavior was potentially due to decreased production of reproductive hormones (luteinizing hormone, follicle-stimulating hormone, and testosterone) (Jacobs et al., 2014). More research is needed to determine whether the CAF diet affects male and female sexual behavior differently, or whether these apparent differences were caused by the timing and/or way of administration.

Social play behavior is a rewarding and widespread social activity among mammals (for a review, Vanderschuren et al., 2016). As social play is crucial during the early phases of development, the two studies applying CAF diet and assessing social play were carried out on young animals. A gestational study found a reduction in social play in pups of dams fed with CAF diet (Ribeiro et al., 2018). Whereas a classical study with adolescent rats found that a CAF diet resulted in more social play compared to STD chow, with females being more playful than males (Lalanza et al., 2014).

This discrepancy in effects on social play could actually also be explained by changes in maternal care behavior. As mentioned above, maternal care might have more influence on pups than the diet itself, because abnormal maternal care is a risk factor for social dysfunction. For example, in a recent meta-analysis, Bonapersona et al. (2019) found that aberrant maternal care behavior reduced social behavior mainly in males. In other words, when a CAF diet is administered to dams, this could influence pups’ behavior through changes in maternal care. Surprisingly, only two studies analyzed the effects of a CAF diet on maternal care, and both found alterations in maternal care, including increased licking/grooming (Speight et al., 2017) and arched nursing and nesting (Ribeiro et al., 2018).

Maternal CAF diet exposure is, therefore, a risk factor for the pups as has been discussed in this review. High fat diets and obesity are also risk factors for the abnormal fetal development (Wentzel et al., 2019) and human studies have also found evidence that maternal obesity is a risk factor for future neurodevelopmental and psychiatric disorders in offspring during adolescence and adulthood (for a review, Baker et al., 2017Rivera et al., 2015).

5. Limitations and Conclusions

The aim of this review was twofold. First, we have aimed to establish a standardized CAF diet protocol that would help the field avoid the current wide-ranging disparities in CAF diet protocols. Second, we have evaluated the current state of knowledge regarding the behavioral effects of exposure to a CAF diet on rodents.

The large amount of inconsistency in results has made it difficult to draw firm conclusions on the effects of this diet on behavioral outcomes. However, overall, we believe we can reasonably conclude that a CAF diet: 1) does not change locomotor activity, 2) increases snacking behavior, and 3) reduces the hedonic value of other rewards such as sucrose and ethanol, a principle similar to the hypofunction or deficiency of the reward and dopaminergic system (Blum et al., 2014Johnson and Kenny, 2010). In addition, exposure to a CAF diet 4) impairs spatial and contextual memory, and 5) tends to have an anxiolytic and antidepressant effects mainly in animal previously exposed to stress. We are, however, very cautious in drawing these general conclusions, because different studies have used widely varying methodologies. Even leaving aside the specifics of how a CAF diet was given, studies varied in terms of age, species, and behavioral tests, all of which could have affected the outcomes. Such differences could well be the reason that we did found insufficient evidence to draw clear conclusions regarding impulsivity, coping behavior and social behavior. The findings suggest that CAF diet altered these behaviors as well, but more research is needed to control for the methodological variations, which hope would lead to more consistent conclusions.

Furthermore, a limitation of this review and the obesogenic diets in general is the difficulty of distinguishing the neuropsychophysiological effects caused by palatable food intake from those derived from the consequently induced overweight/obesity. To illustrate this problem, a negative correlation has been found between the amount of dopaminergic receptors and body weight (de Weijer et al., 2011Michaelides et al., 2012Wang et al., 2001). Taking into account that palatable diet in the form of junk and ultraprocessed food is a major cause of obesity (Rosenheck, 2008), it is likelythat the food‒body weight interaction is a vicious circle phenomena, because long-term consumption of junk food also affects the dopaminergic signaling (as mentioned above). For instance, women who gained weight during the last six months had a lower striatal response towards palatable food compared to stable-weigh women. This could increase the vulnerability for overeating (as a compensatory mechanism of stimulating a hypofunctional reward system) and result in increases in body weight (Stice et al., 2010).

The large variation in the feeding protocols used to study the effects of CAF diet exposure could also have caused the different behavioral outcomes. In order to improve coherence between experiments, and thereby allow comparisons between studies, we propose that researchers will use a standardized protocol. Therefore, we propose that future CAF protocols should: 1) combine different tastes, textures and nutrients; 2) include salty and sweet products as well as products containing chocolate elements; 3) rotate and vary the diet each day, with the menu structure as an excellent tool; 4) give animals ad libitum access to the CAF diet; and 5) offer a healthy (or standard) alternative, since a CAF diet must be available voluntarily and chosen due to its palatability.

Nowadays, junk food is highly prevalent in Western societies and plays a key role in the epidemic of overweightness and obesity, which underlies the corresponding epidemic in non-communicable diseases such as diabetes and cardiovascular disease. Basic animal research is necessary to understand not only the physiological and behavioral effects of junk food, but also to comprehend the triggers and risk factors for overeating these kinds of food products. They will also inform the development of potential treatments for obesity. As we have argued, the CAF diet is an excellent model for recapitulating current problematic human eating patterns due to its high construct validity. The standardized CAF diet protocol proposed herein would enhance comparisons between research laboratories, thereby aiding the understanding of the obesity epidemic and developing ways to mitigate it.

Truth-making institutions: From divination, ordeals and oaths to judicial torture and rules of evidence

Truth-making institutions: From divination, ordeals and oaths to judicial torture and rules of evidence. Hugo Mercier, Pascal Boyer. Evolution and Human Behavior, December 10 2020. https://doi.org/10.1016/j.evolhumbehav.2020.11.004

Abstract: In many human societies, truth-making institutions are considered necessary to establish an officially valid or “received” description of some specific situation. These range from divination, oaths, and ordeals to judicial torture or trial by jury. In many cases, these institutions may seem odd or paradoxical, e.g., why would an ordeal reveal a defendant's guilt or innocence? Here we propose to address the questions, why those institutions are considered the source of accepted truth, and why they have recurrent features in many different cultures. Our model is based on two well-documented set of evolved cognitive mechanisms. One is epistemic vigilance, the set of cognitive processes that help us evaluate the quality of communicated information we receive. We show how our epistemic intuitions account for otherwise puzzling aspects of divination, oaths, and ordeals. The other set of mechanisms consists in human capacities for coalition building and the recruitment of social support, which explains how truth-making institutions can be strategically used by individuals to influence mutual knowledge for their own interests. Taken together, these mechanisms explain the kinds of institutions found in small-scale societies (oaths, ordeals, divination), as well as the emergence of different institutions (laws of evidence, judicial torture, trial by jury) in large-scale and modern societies.


Keywords: InstitutionsLegal anthropologyEpistemic vigilanceDivinationLaws of evidence


Critical review of uniform color effects in sports

Critical review of uniform color effects in sports. Nadav Goldschmied, Philip Furley & Ruth Bush. International Review of Sport and Exercise Psychology, Dec 10 2020. https://doi.org/10.1080/1750984X.2020.1855668

Abstract: Groundbreaking research linking uniform colors and performance in sport has gained momentum in recent years demonstrating a superiority effect associated with certain colors, especially red, and an increase in aggression when in black. However, the findings are not uniform and some studies find no association. Our objective was to identify, compare, and disseminate a comprehensive list of studies associated with uniform colors and performance. This critical review identified 33 studies in sport, which explored the phenomenon and met the criteria for inclusion. We used the color-in-context theory (Elliot, A. J., & Maier, M. A. (2007). Color and psychological functioning. Current Directions in Psychological Science, 16(5), 250–254; Elliot, A. J., & Maier, M. A. (2014). Color psychology: Effects of perceiving color on psychological functioning in humans. Annual Review of Psychology, 65(1), 95–120 ) as the foundation for our analysis of the findings and, in turn, exposed some incoherence of some constructs and boundary conditions set by this framework. In the current work, we specifically distinguish between performance research and perception-only work and illuminate the differences as they pertain to theoretical underpinning. Based on present findings, we conclude that the evidence for uniform colors to influence the outcome of athletic competitions is weak and that more investigation is required to substantiate the effect, if it does exist. We conclude by proposing future avenues of research both as they pertain to features of the sports studied but also for the methodology utilized.


Thursday, December 10, 2020

Advertising a healthy default reduces interest in visiting the restaurant; that is, advertising healthy defaults drives away first-time sales

Dodging dietary defaults: Choosing away from healthy nudges. Helen Colby, Meng Li, GretchenChapman. Organizational Behavior and Human Decision Processes, Volume 161, Supplement, November 2020, Pages 50-60. https://doi.org/10.1016/j.obhdp.2020.10.001

Abstract: The default effect has been identified as a powerful tool to influence behavior; however, the current studies demonstrate that consumers dodge the effects of healthy defaults by selecting away from the healthy default environment, thereby reducing its effect. Two studies with real consequences and three hypothetical scenario studies in restaurant settings demonstrate that healthy defaults promote healthy food choice in the moment, but consumers choose to put themselves in environments with unhealthy defaults over those with healthy defaults. That is, healthy defaults negatively impact sales and willingness of consumers to return to the restaurant that offers them. Study 1 provides initial evidence that a healthy default reduces sales of the product compared to a less healthy default in a real gift shop. Study 2 uses an online survey with real consequences and demonstrates that participants prefer to receive meal kits from a company with unhealthy defaults over one with healthy defaults. Studies 3–5 use hypothetical scenarios to demonstrate the tendency for consumers to dodge healthy defaults. Study 3 shows that a healthy default can drive away future sales. Study 4 demonstrates that advertising a healthy default reduces interest in visiting the restaurant; that is, advertising healthy defaults drives away first-time sales. Finally, Study 5 shows that this dodge effect is robust in a between-subject manipulations using a well-known brand. The results demonstrate that consumers dodge healthy defaults by migrating to environments where unhealthy defaults are in place.

Keywords: Default effectCognitive dissonanceConsumer behaviorHealthy eating


7. General discussion

Our studies demonstrated a dodge effect: Consumers avoid purchasing the product if it has a healthy default in place (Study 1), select a different meal-kit brand when the default is healthy (Study 2), avoid returning to a restaurant with a healthy default (Studies 3, and 5), and avoid selecting a restaurant advertising a healthy default (Study 4). Note that the current studies demonstrate two variants on the dodge effect: (i) choosing to purchase something else (or nothing at all) when the defaults is healthy (Studies 1, 2, 4) and (ii) choosing the healthy default when presented with it, but then avoiding that store/restaurant in the future (Studies 3, 5). This dodge effect can reduce the impact of default manipulations, as consumers with preferences that do not match the default will avoid being exposed to that default. Simultaneously, the dodge effect could inflate the apparent impact of a default manipulation in a non-experimental setting, as the large percentage of consumers sticking with the healthy default may in part reflect a self-selecting effect: consumers who do not wish to consume the healthy option may have simply been chased away.

The current results point to the importance of examining the effect of defaults and other nudges not only in the local environment where they are in place, but also in upstream decisions when decision makers select which environment to enter and in downstream decisions where decision makers choose whether to return to an environment. Our results suggest that consumers may avoid environments where it is difficult to satisfy their preferences (e.g., when the environment has a healthy but unappealing food default in place).

The current studies do not pinpoint the mechanism behind the dodge effect. We speculate that one likely mechanism is that many consumers mindlessly accept the default. Consequently, they experience a meal that is not tasty and attribute that poor experience to the restaurant, rather than to their own acceptance of the default. Note, however, that it is not necessary for the consumer to experience the default healthy outcome for a dodge effect to manifest, as Study 4 demonstrates that consumers dodge healthy defaults when initially selecting a restaurant. Other mechanisms are also possible. For example, opting out of healthy default (to obtain the unhealthy food) may incur physical or psychological costs relative to obtaining the same unhealthy food by accepting an unhealthy default. Opting out of healthy default requires some effort, but it may also signal vice to the decision maker or others, or it may make the decision maker feel guilty or feel angry that others appear to be trying to make her feel guilty about her choice. Testing these and other specific mechanisms is outside the scope of the current paper but is an interesting topic for future research. Regardless of the mechanism, restaurants that set a healthy default risk losing customers.

Thus, while healthy defaults have a strong positive effect on food consumption, they may not be the easy answer to the obesity crisis that some have suggested, as the dodge effect may present serious hurdles for business owners interested in implementing healthy defaults. However, consumers may be less likely to dodge healthy defaults when it is not feasible to leave one environment and move to another. For example, in school lunchrooms and workplace cafeterias where customers have few other options but to eat within the facility, implementing healthy defaults could provide large health benefits without driving down sales or driving away customers.

It is important to note that the current results indicate that the dodge effect will reduce the effect of healthy defaults on consumptions of healthy food relative to what would be expected given no dodge; however, the net effect of the healthy default on consumption is nevertheless still positive: more healthy food is consumed under a healthy default than under an unhealthy default. The current studies found large default effects but modest sized dodge effects. We computed the net size of default effect as the difference between the proportion of participants’ choices that stuck with the default and 50%, the proportion expected from the hull hypothesis. Similarly, we computed the net size of the dodge effect as the difference between the observed proportion of participants choosing the healthy default establishment and 50%, as expected from the null hypothesis (see Table 1). The weighted means of net default effect and net dodge effect were 25.6% and 6.9%, respectively, suggesting that the magnitude of dodge effect is roughly 27% of the size of the default effect. Thus, although consumers are somewhat less likely to patronize a restaurant with a healthy default, compared to one with an unhealthy default, once the consumers are inside the healthy default restaurant, the default will have a notable effect of food choice.

...

The primary beneficiary of healthy defaults are consumers, who are encouraged to eat foods that benefit their long-term health. An equally important set of stake holders, however, are the restaurants and other businesses with the power to set healthy defaults. If customers dodge healthy defaults, even to a limited extent, businesses stand to lose revenue if they set healthy defaults, relative to setting defaults as the less healthy but tastier alternative. Consequently, the dodge effect poses a barrier to public health initiatives to encourage businesses to set healthy defaults. Future research can examine whether alternatives to healthy defaults, such as having no default but always asking consumers to make a choice among healthy and unhealthy food options, can eliminate the dodge effect and are hence more palatable for businesses.

Defaults can be a powerful tool to promote healthy eating behavior. The current studies provide new evidence and insights into the limitations of default manipulations. Because consumers can dodge the effects of defaults, the long-term effects of default manipulations are likely to be smaller than previously thought. Such findings can help health officials as well as business owners decide what healthy defaults might be appropriate to implement, so that people will make more healthy choices, and stick with them.

Having a nondifficult partner is associated with lower loneliness compared to having no partner, but having no partner and having a difficult partner are related to similar levels of loneliness

They Drive Me Crazy: Difficult Social Ties and Subjective Well-Being. Shira Offer. Journal of Health and Social Behavior, September 10, 2020. https://doi.org/10.1177/0022146520952767

Abstract: Using egocentric network data from the University of California Social Networks Study (1,136 respondents; 11,536 alters), this study examines how difficult ties—an unexplored form of social negativity—are associated with well-being. Findings show that well-being is affected by the quality of the relationship rather than its presence in the network. Having a nondifficult partner is associated with lower loneliness compared to having no partner, but having no partner and having a difficult partner are related to similar levels of loneliness. Likewise, having difficult adult children and having no adult children are associated with reporting greater psychological distress than having nondifficult adult children. Consistent with the stress process model, the negative association of a difficult partner with well-being is buffered when that partner is otherwise supportive and when the other ties in the network are supportive. However, that association is amplified when the other ties are also difficult.

Keywords: difficult ties, egocentric networks, loneliness, personal relationships, social support, well-being


The Neuroscience of Positive Emotions and Affect: Implications for Cultivating Happiness and Wellbeing

The Neuroscience of Positive Emotions and Affect: Implications for Cultivating Happiness and Wellbeing. Rebecca Alexander et al. Neuroscience & Biobehavioral Reviews, December 8 2020. https://doi.org/10.1016/j.neubiorev.2020.12.002

Highlights

• Neurophysiological correlates of positive emotions contribute to wellbeing.

• Brain networks that implement positive emotions are flexible and modifiable.

• Developmental, social, and environmental factors impact positive emotions.

• Meditation, contemplative practices, and flow cultivate positive emotions.

• Linguistic dimensions contribute to advancing the neuroscience of positive emotions.

Abstract: This review paper provides an integrative account regarding neurophysiological correlates of positive emotions and affect that cumulatively contribute to the scaffolding for positive emotions and wellbeing in humans and other animals. This paper reviews the associations among neurotransmitters, hormones, brain networks, and cognitive functions in the context of positive emotions and affect. Consideration of lifespan developmental perspectives are incorporated, and we also examine the impact of healthy social relationships and environmental contexts on the modulation of positive emotions and affect. The neurophysiological processes that implement positive emotions are dynamic and modifiable, and meditative practices as well as flow states change patterns of brain function and ultimately support wellbeing are also discussed. This review is part of “The Human Affectome Project” (http://neuroqualia.org/background.php), and in order to advance a primary aim of the Human Affectome Project, we also reviewed relevant linguistic dimensions and terminology that characterizes positive emotions and wellbeing. These linguistic dimensions are discussed within the context of the neuroscience literature with the overarching goal of generating novel recommendations for advancing neuroscience research on positive emotions and wellbeing.

Keywords: NeurosciencePositive EmotionsPositive AffectWellbeingLinguistics

10. Conclusions

Arguably, it is the experience, interpretation, and regulation of positive stimuli and emotions whose cumulative effects ultimately lead to the experience of happiness, life satisfaction, and wellbeing (Bryant, 2003Cohn et al., 2009Diener et al., 2009Silton et al., 2020). As this present review illustrates, experiencing positive emotions benefits psychological and physical wellbeing in numerous, intersecting ways, including modulating neurophysiological correlates within the central and peripheral nervous systems. Yet, rates of mental health problems are rising and negatively impacting daily life function for an increasingly large number of people across the lifespan (World Health Organization, 2017). At the societal level, this poses problematic implications for complicating the recovery from co-occurring noncommunicable health disorders (e.g., obesity, diabetes, asthma, etc.; World Health Organization, 2014) and these issues are often accompanied by deteriorating social bonds and community support.

Noting the importance of happiness and wellbeing in social progress at the global level, the United Nations commissioned its first World Happiness Report (WHR) in 2012 (Helliwell et al., 2012). This report, based on a single rating of happiness, suggests some geographical regions score above (Northern America, Australia, and New Zealand; Western, Central, and Eastern Europe; and Latin America and the Caribbean) and below (sub-Saharan Africa and South Asia) the mean global level of happiness. According to the 2018 WHR (Helliwell et al., 2018), nearly 75% of the variability in global levels of happiness is explained by six factors: 1) the perceived availability of social support, 2) national gross domestic product (GDP), 3) average healthy life expectancy, 4) the perceived freedom to make life choices, 5) generosity as indicated by self-reported monetary donations to a charity, and 6) perceived levels of corruption. Other research based on multiple waves of the World Value Survey has shown that the greater the inequality in income within nations, the greater the inequalities in national happiness and life satisfaction (Ovaska & Takashima, 2010). While many of the items reflect high-level structural factors that governing bodies can aim to influence, the findings from our present review highlight the importance of strong social bonds for achieving happiness and wellbeing (section 6.1) which remain an area that individuals and community-based organizations can work to cultivate via strategic urban design and built environments (section 7) that create space and opportunities for meaningful social connections (Bates et al., 2018).

While scholars and policymakers have increasingly recognized the importance of happiness and wellbeing in assessing progress and development around the globe, one nation in particular – the small nation of Bhutan nestled between India and China – has explicitly committed to the national goal of enhancing happiness (Helliwell et al., 2012Nidup et al., 2018). In Bhutan, happiness is defined holistically as encompassing economic, spiritual, social, cultural, and ecological perspectives and the government has been actively engaged in increasing the proportion of citizens who meet sufficiency standards on a range of indicators of deprivation (e.g., water, sanitation, electricity, education; Nidup et al., 2018). Bhutan’s culture is strongly rooted in the Buddhist religion and spirituality as well as compassion are core components of Bhutanese life and are viewed by the Bhutanese authorities as essential to the domain of Gross National Happiness Index (Helliwell et al., 2012). While global levels of happiness are related to GDP and income, psychological wellbeing also contributes to national levels of happiness resulting in the assessment of these factors by the United Nations in recent years with Bhutan having explicitly committed to increasing happiness levels among its citizens. Ostensibly, many of the components of happiness reviewed in the present paper are incorporated into the everyday fabric of life in Bhutan.

Short of living in Bhutan, actively engaging in behaviors that are associated with happiness and wellbeing may need to be actively practiced in contemporary society across the lifespan. As reviewed in section 8.1., mindfulness meditation and loving-kindness meditation have been linked with positive emotion outcomes and wellbeing, but additional research is needed to understand how “dosage,” and specific components of contemplative practices modulate positive emotions and associated neurophysiological correlates. Similarly, the positive psychology literature has developed a number of evidence-based strategies designed to increase and enhance positive emotions (Quoidbach et al., 2015), yet very little is known about how human neurophysiology might change in response to these strategies, and this remains an area for future research (Silton et al., 2020). Given that increased happiness is frequently observed in late life, future research may benefit from harnessing some of the strategies that are naturally employed by older individuals to enhance the experience of positive emotions (see section 5.2).

Since the present review paper is largely focused on happiness and wellbeing outcomes, we have skirted the topic regarding the relation between positive emotion dysregulation and psychopathology. Needless to say, the experience of excessive happiness and positive emotions can have negative implications for psychological wellbeing, such that experiencing positive emotions in excess is related to bipolar disorder (e.g., Gruber, 2011). Other disturbances in positive emotion regulation have been associated with depressive disorders (Silton et al., 2020). Research on “emodiversity” postulates that experiencing a range of positive and negative emotions is associated with positive health outcomes (Quoidbach et al., 2014) and additional research may be warranted to contextualize the role of positive emotions within individuals’ affective repertoire, with close to consideration of environmental and contextual factors, including the role of culture.

Given the importance of positive emotions to psychological health, the Research Domain Criteria (RDoC) initiative within the United States’ National Institute of Mental Health has a distinct domain dedicated to positive emotions titled “Positive Valence Systems.” However, the terminology employed in positive emotion research, or in the linguistic adjudication in the present review is much broader and diverse than the terminology associated with the Positive Valence Systems domain in the RDoC matrix, which has become a prominent multidimensional model used to classify mental disorders for research purposes. Progress in theoretical and treatment development will benefit from the reconciliation of the terms and constructs represented in the RDoC matrix with those typically employed in the field (Gruber et al., 2019). The RDoC initiative is aiming to move the needle on enhancing prevention and intervention approaches to psychological disorders. The stakes are high, and linguistics may be important to guide the inclusion of broader positive emotion constructs into the RDoC that go beyond reward, learning, efforts, and habit. Much of the neurophysiological research reviewed in the present paper is correlational, and by expanding the RDoC Positive Valence Systems to incorporate a broader positive emotions nomenclature, longitudinal, experimental, and intervention research will accelerate and more specific mechanisms of positive emotions may be identified.

Finally, animal research pertaining to happiness and positive emotions is integrated throughout this review. With regard to the study of positive emotional states in animals has progressed over the last years, much remains to be learned. A better understanding of positive emotions in animals, across taxa, will contribute to advancing knowledge regarding human positive emotions and their evolutionary origins (Anderson & Adolphs, 2014de Vere and Kuczaj, 2016). Additionally, it is an important tool to improve the welfare of captive animals (Boissy et al., 2007). Thus, we echo previous calls made by other researchers to counterbalance the bias toward studying negative emotions in animals and humans and continue to shift the focus toward the study of positive emotions in order to enhance our understanding of critical factors and strategies that contribute to societal happiness and wellbeing.

They propose that if rats in cocaine choice studies choose the alternative reward so often, it is likely because the delay to cocaine reward is longer than it is for the nondrug reward (sweetened water here)

Sugar now or cocaine later? Anne-Noël Samaha. Neuropsychopharmacology Sep 1 2020, volume 46, pages271–272(2021). https://www.nature.com/articles/s41386-020-00836-z

Rolf Degen's take: https://twitter.com/DegenRolf/status/1336722778238627840

A few years ago, I was teaching a graduate course on drugs of abuse and addiction. We were on the topic of preclinical choice studies, where laboratory rats must make a mutually exclusive choice between self-administering cocaine or an alternative reward (e.g., sweetened water, appetitive foods, or another rat to interact with). These studies consistently show that most rats prefer the nondrug reward over cocaine [1] (and over heroin or methamphetamine [2,3,4,5]). After I had reviewed these studies in my class, a student asked, ‘Does this mean that sugar is more addictive than cocaine?’. This question summed up the problem. Across species, drugs like cocaine are thought to have rewarding effects that greatly surpass those of other, nondrug rewards. So, shouldn’t most rats choose cocaine? Yet, most rats choose the other, nondrug reward instead. This is true for both sexes, and even for rats with rather extensive drug using histories.


Nobody is better than you: opportunistic moral identity of sexual batterers

Nobody is better than you: opportunistic moral identity of sexual batterers. María Patricia Navas, Jorge Sobral, José Antonio Gómez-Fraguela, Beatriz Domínguez-Álvarez, and Aimé Isdahl-Troye. Psychology and Law: Research for practice, Dec 2020, pp 37–50. https://doi.org/10.2478/9788395669682-004

Abstract: Modern societies devise sexual violence as a social problem. Legal psychologists highlight the importance of identifying those variables that increase the likelihood of violent behaviour occurs – risk factors- and those variables that increase their opposition to have deviant behaviours -protective factors-. For these reasons, the objective of this work is to study moral identity and moral disengagement as variables strongly related to violent behaviour, in a sample of institutionalized men (sexual offenders and intimate partner batterers) and in a sample of community men to analyse the differences between them. The sample was composed of 91 convicted and 133 community participants who voluntarily completed The Self-Importance of Moral Identity Scale and The Propensity to Moral Disengagement Scale. Variance analysis, bivariate correlations and hierarchical regressions were performed in order to analyse the differences in each of the variables between groups; to test the relationships between study variables, and to find out which mechanisms of moral disengagement are associated with both factors of moral identity in each group. Results show significant differences between groups in both factors of moral identity (internalization F (1, 224) = 20.72, p <.001; and symbolization F (1, 224) = 14.52, p <. 001). Bivariate correlations showed relationship only between symbolization and moral disengagement in institutionalized participants and lastly, different mechanisms of moral disengagement were associated with both factors of moral identity in each group. Finally, the practical implications of these results were discussed to improve the psychological interventions with sexual offenders and intimate partner batterers.

Keywords: Sexual assault, Intimate partner violence, Moral identity, Moral disengagement, Risk factor


Observers who score high in the moral identity test have particularly strong reactions to acts of hypocrisy, but fail to produce a proportional amount of punishment; there is a widespread behavioral reluctance to punish hypocrites

Jauernig, Johanna; von Grundherr, Michael; Uhl, Matthias (2020): To Condemn is Not to Punish: An Experiment on Hypocrisy, Beiträge zur Jahrestagung des Vereins für Socialpolitik 2020: Gender Economics, ZBW - Leibniz Information Centre for Economics, Kiel, Hamburg. https://www.econstor.eu/bitstream/10419/224558/1/vfs-2020-pid-39485.pdf

Abstract: Hypocrisy is the act of claiming moral standards to which one’s own behavior does conform. Instances of hypocrisy, such as supposedly green car manufacturer Volkswagen’s emissionsrelated scandal, are frequently reported in the media. In a controlled and incentivized experiment, we find that observers do, indeed, condemn hypocritical behavior strongly. The aversion to deceptive behavior is, in fact, so strong that even purely self-deceptive behavior is regarded as blameworthy. Observers who score high in the moral identity test have particularly strong reactions to acts of hypocrisy. The moral condemnation of hypocritical behavior, however, fails to produce a proportional amount of punishment. Punishment seems to be driven more by the violation of the norm of fair distribution than by moral pretense. If a broad societal consensus exists with regard to the moral reprehensibility of hypocrisy, it may be necessary to implement institutional sanctions, given the widespread behavioral reluctance to punish hypocrites.


School bullying is positively associated with support for redistribution in adulthood

School bullying is positively associated with support for redistribution in adulthood. Atsushi Yamagishi. Economics of Education Review, Volume 79, December 2020, 102045. https://doi.org/10.1016/j.econedurev.2020.102045

Abstract: I document that being bullied at school has a strong positive association with support for redistribution in adulthood. Using unique Japanese survey data, I estimate that the bullied are 5–7 percentage points more likely to support redistribution. I carefully examine whether omitted factors drive this positive association by considering a rich set of socioeconomic and psychological mediators. The estimate is robust to such controls.

Keywords: Support for redistributionSchool bullyingLong-run impact

JEL D72 H23 I20


Wednesday, December 9, 2020

Rolf Degen summarizing... There was no connection between the attractiveness of the face and the voice, again casting doubt on the "good genes" theory of physical attractiveness

Attractiveness and distinctiveness between speakers' voices in naturalistic speech and their faces are uncorrelated. Romi Zäske, Verena Gabriele Skuk and Stefan R. Schweinberger. Royal Society Open Science, December 9 2020. https://doi.org/10.1098/rsos.201244

Rolf Degen's take: https://twitter.com/DegenRolf/status/1336606172384735233

Abstract: Facial attractiveness has been linked to the averageness (or typicality) of a face and, more tentatively, to a speaker's vocal attractiveness, via the ‘honest signal’ hypothesis, holding that attractiveness signals good genes. In four experiments, we assessed ratings for attractiveness and two common measures of distinctiveness (‘distinctiveness-in-the-crowd’, DITC and ‘deviation-based distinctiveness', DEV) for faces and voices (simple vowels, or more naturalistic sentences) from 64 young adult speakers (32 female). Consistent and substantial negative correlations between attractiveness and DEV generally supported the averageness account of attractiveness, for both voices and faces. By contrast, and indicating that both measures of distinctiveness reflect different constructs, correlations between attractiveness and DITC were numerically positive for faces (though small and non-significant), and significant for voices in sentence stimuli. Between faces and voices, distinctiveness ratings were uncorrelated. Remarkably, and at variance with the honest signal hypothesis, vocal and facial attractiveness were also uncorrelated in all analyses involving naturalistic, i.e. sentence-based, speech. This result pattern was confirmed using a new set of stimuli and raters (experiment 5). Overall, while our findings strongly support an averageness account of attractiveness for both domains, they provide no evidence for an honest signal account of facial and vocal attractiveness in complex naturalistic speech.

4. General discussion

4.1. Relationships between attractiveness and distinctiveness

The present study is to our knowledge, the first to demonstrate a systematic relationship between perceived attractiveness and distinctiveness in human voices. Here, we found strong negative correlations between attractiveness and deviation-based distinctiveness (DEV) for voices when based both on vowels (ρ = −0.85) and on sentences (ρ =−0.87). This pattern was analogous to and, if anything, even stronger than the previously described negative correlation between attractiveness and DEV for faces (experiment 2: ρ = −0.64; experiment 4: ρ = −0.74). Overall, this pattern of findings provides strong support for an averageness account of attractiveness for both faces and voices [3,7] when distinctiveness is assessed in a deviation-based manner. Note, that the negative relationship between attractiveness and DEV was not merely an artefact of imitating a model speaker during voice recordings: in experiment 5 using new speakers, we replicated our results for voices recorded with the model, but also found significant, though smaller, negative correlations for voices recorded without model speaker (vowels: ρ = −0.46, and sentences: ρ = −0.59). While this indicates that the presence of a model partially preserves idiosynchratic variability in voices which drives the relationship between attractiveness and DEV in terms of stable ‘voice traits’, speaking after a model enhances the strength of this relationship, perhaps owing to a change of natural voice variation affecting either attractiveness, DEV or both. Based on correlations across recording modes, which were substantial and positive for attractiveness, but tended to be relatively smaller for DEV ratings (at least for vowels), we tentatively suggest that the presence of a model speaker may change natural variation of DEV more than variation of attractiveness. Note, however, that mean F0 was remarkably similar across the recording modes. The notion that the relationship between attractiveness and DEV is systematic and substantial, independent of recording mode, is further supported by strong and positive cross-sentence correlations throughout for attractiveness ratings (0.64 ≤ ρ ≤ 0.77) as well as for DEV ratings (0.63 ≤ ρ ≤ 0.79), with no significant difference between recording modes.

The present findings are important because they were obtained in the context of ratings for real stimuli, rather than for averaged ‘composite’ stimuli. Note that averaging towards composites causes artefacts per se, such as smooth and symmetric visual patterns for faces, or increased harmonics-to-noise ratios for voices. (It should also be noted, however, that voice morphing is a comparatively new and elaborate technique which only a few laboratories master, and this may also explain why there are relatively few studies investigating the averageness account of vocal attractiveness.) We propose that, because such ‘non-average’ features of digitally created composites have been shown to consistently contribute to perceived attractiveness [7,14], studies with natural individual stimuli that vary in perceived prototypicality or averageness are important to cross-validate findings obtained with composite stimuli.

Compared to these consistent findings of negative correlations between attractiveness and deviation-based distinctiveness, the relationship with rated attractiveness was much less consistent for ‘in-the-crowd’-based distinctiveness ratings. Specifically, while there was also a moderate negative correlation between attractiveness and ‘in-the-crowd’-based distinctiveness (VITC) for voices when based on vowels (experiment 1), this correlation was positive when based on sentences (experiment 3). For faces, a marginally non-significant positive correlation between attractiveness and FITC was found in experiment 1 (numerically similar to the significant positive correlation with more stimuli as reported in [34]), and while this pattern was not seen in experiment 3 using the same stimuli and task, the relationships between rated attractiveness and DITC ratings were inconsistent when compared to DEV ratings. Taken together, our findings confirm that common deviation-based and ‘in-the-crowd’-based measures of distinctiveness (VITC and FITC) measure at least partially different constructs [34], and extend those findings by showing that this is the case both for faces and for voices. For voices, the specific relationship between attractiveness and distinctiveness appears to depend on the type of utterance. Specifically, while simple vowel stimuli were rated as less attractive with increasing VITC distinctiveness (experiment 1), in line with an averageness account, sentence stimuli (experiment 3) were rated as more attractive with increasing VITC distinctiveness.

These differences between different types of utterances may generally be related to differences in duration and/or number of different phonemes [6,59]. Whereas sentences carry much richer cues to attractiveness and distinctiveness, vowels are simple periodic utterances which are mainly influenced by ‘static’ biophysical characteristics of individual speakers. VITC ratings for vowels could also differ from those for sentences owing to a certain oddity of imagining someone saying a prolonged vowel sound in a crowd. Possibly related to this notion, an earlier study reported that perceived voice attractiveness and acoustic distance to mean (in terms of F0, F1) were correlated for a vowel (/a/), but not for a word or sentence [6]. Overall, ratings of attractiveness and VITC distinctiveness are probably based on partially different sets of acoustic cues, depending on their salience in a given utterance. The positive correlation between voice attractiveness and VITC distinctiveness is reminiscient of analogous findings for faces in previous research [34] where it has been argued that DITC measures of distinctiveness may be distorted by cognitive heuristics. Accordingly, raters might be biased to think that they would surely spot a highly attractive person in the crowd, even when this might not be the case. Such an effect seems to generalize to voices in the present study, at least when ratings are based on sentence stimuli. Note that such a putative heuristic, as suggested here, does not imply that attractive voices would, in fact, stand out of a crowd if put to test. (In fact, other more salient bottom-up acoustic characteristics such as intensity [60] probably play a more prominent role here which we had controlled in our stimuli by RMS normalization.) While we are at present unaware of studies addressing the specific issue of whether attractive voices stick out from a noisy environment, a recent study on the ‘cocktail-party effect’ [61] could provide tentative and indirect evidence in favour of this assumption. Specifically, interference from a non-target speaker can be reduced both when the target is familiar and the interfering voice is unfamiliar and, critically, also when the target is unfamiliar and the interfering voice is familiar [62]. Although the link to attractiveness is indirect, voice familiarity, just like voice averaging (and, by implication, attractiveness), could promote positive evaluation via a fluency mechanism as seen in the mere exposure effect.

In contrast to ‘in-the-crowd-based’ measures of distinctiveness, correlations for deviation-based distinctiveness and attractiveness were highly consistent, and consistently negative across modalities and utterance types in the present study. This supports the notion that both faces and voices become increasingly attractive the more typical, i.e. the more average, they are perceived relative to prior personal experience [3,7]. At variance with this experience-based account of typicality, it has been argued recently that typicality ratings rather reflect stereotypes of what constitutes attractive and typical voices [9]. In our view, this may be the case for tasks that do not further specify what typicality/distinctiveness is. However, it should be noted that our task explicitly invoked a memory component by asking participants to judge distinctiveness relative to the faces and voices they know. Given the different patterns of results for two types of distinctiveness measures, we believe that it is extremely important for future studies to specify exactly how typicality/distinctiveness was assessed.

Overall, while deviation-based measures gave rise to a highly consistent pattern of negative correlations with attractiveness across stimulus modalities and domains, inconsistent correlations were seen for attractiveness and DITC measures which may be distorted by subjective heuristics. This may indicate that DEV ratings are preferable over ‘in-the-crowd’-based measures to assess distinctiveness in an unbiased manner.

4.2. Relationships between ratings for faces and voices of the same speakers

The second aim of the present study was to provide a systematic assessment of relationships between ratings of attractiveness and distinctiveness for faces and voices from the same speakers. Positive correlations between independent ratings of faces and voices might be expected to the extent that (i) facial and vocal features are determined by the same underlying basis (e.g. genetic or hormonal), and (ii) those features systematically influence perceptions under investigation (e.g. of attractiveness or distinctiveness). A common basis of vocal and facial attractiveness has been postulated by several studies (e.g. [35,41,43]). While we are unaware of research directly linking attractiveness and hormonal status via distinctiveness, there is evidence that certain vocal parameters (e.g. F0, vocal tract length estimates, shimmer, jitter, harmonics-to-noise ratio, as determined from sustained vowel recordings only) are linked to speakers' body size measurements (e.g. height, weight and waist-to-hip ratios), as probably mediated by hormonal mechanisms [63]. The present findings, however, consistently indicate that correlations between vocal and facial attractiveness are remarkably absent in the majority of the studied conditions, and small at best in one exception which we discuss below (figure 2). It could be argued that the standardization of the present stimuli in terms of neutral emotional expression and speaking style according to a model speaker, may have compromised to some degree the natural variation between voices relevant for perceived attractiveness, such as vocal pitch.

However, experiment 5 addresses this concern, and its results are clear in showing that correlations between facial and vocal attractiveness in sentences were also absent for voices recorded naturally and without a model speaker, as predicted [55] based on our findings from experiment 4. Although we had no predictions regarding the small positive correlation (ρ = 0.30) between facial and vocal attractiveness for simple vowels we had observed in experiment 1, it may be noted that this was not replicated in experiment 5. Rather, we found a numerically negative, though non-significant correlation (ρ = −0.30) in the condition with model speaker, and a numerically negative non-significant correlation (ρ = −0.18) in the new condition without a model speaker. Overall, the pattern of results across five experiments would seem to indicate that, for a range of conditions tested in this series of experiments, any correlation between facial and vocal attractiveness is small at best, and is potentially non-existent.

Together, the present findings challenge the ‘honest signal account’ of facial and vocal attractiveness [14]. On one hand, we appreciate that the only exception to this pattern, a small but significant positive correlation between facial and vocal attractiveness in experiment 1, when simple vowels were used as voice samples, could potentially resolve discrepancies between our data and previous findings in which evidence for a correlation between facial and vocal attractiveness was reported using similarly simple vocalizations [41,43]. On the other hand, our failure to replicate this finding with a new set of speakers emphasizes the importance for researchers both to critically consider the nature of the stimuli used to assess these relationships, and to assess the replicability of critical findings across a range of conditions and situations.

In that respect, prerequisites to find evidence for or against the honest signal hypothesis include that face and voice stimuli should be honest and undistorted representations of their owners' genetic quality. We selected our face stimuli to be devoid of attractiveness-enhancing features such as make-up or jewellery. However, it may be more difficult to remove or standardize socio-cultural norms of attractiveness that are reflected in acquired speech patterns in the voice [9]. In that sense, the present voice ratings to more naturalistic sentence stimuli may in part reflect cultural norms, rather than purely biophysically determined voice qualities. Accordingly, one explanation for the results found with simple vowels could be that these are relatively devoid of such socio-cultural cues, and thus may reflect genetic factors more ‘honestly’ compared to more naturalistic and complex vocalizations. While this interesting possibility should be addressed in more detail in future research, we can conclude that correlations between vocal and facial attractiveness appear to be remarkably absent, at least when voices are presented in the more naturalistic context of sentences (as opposed to vowels) akin to everyday communication.

Although acoustic analyses on vowel pitch and sentence duration did not indicate different degrees of acoustic variability for samples recorded with, versus without, the model speaker, electronic supplementary material, table S19 suggest approximately 10% longer average durations of the same sentences when produced with compared to without a model speaker. We tentatively attribute this difference to the larger effort to imitate neutral emotion and speaking style of a model.

With respect to distinctiveness, facial and vocal ratings were uncorrelated for both types of distinctiveness ratings, suggesting no common basis for perceived distinctiveness. An interesting question for future research is how various measures of vocal distinctiveness could be related to one another. For instance, it would be instructive to assess in more detail how DITC and DEV are related with the actual recognizability of voices (for relevant research on faces, see [34,64,65]), and to determine the acoustic stimulus parameters which underlie different aspects of perceived vocal distinctiveness (for relevant methods, see [66]).

4.3. Limitations

As a possible limitation for both the present study and earlier research in this field [35,40,41,43], we assessed attractiveness and distinctiveness for static faces, and thus did not consider a possible role of dynamic facial information. To the extent that static and dynamic faces may be judged by different standards [67], it remains possible that cross-domain correlations between facial and vocal attractiveness could be found for dynamic facial stimuli. In fact, one previous study emphasized the role of dynamic information for correlations between vocal and visual attractiveness, although this was not found consistently across different conditions [68]. Recent theoretical accounts of person perception increasingly address the role of dynamic information [69], and this issue warrants further investigation.

As a second step towards understanding impression formation in every-day social interaction, it may be of interest how faces and voices combine to shape our evaluation of a person's attractiveness. Clearly, simultaneous presentation of face-voice stimuli would be unsuited to study the honest-signal account of attractiveness which requires independent ratings of (unimodal) voices and faces, owing to possible multimodal interactions. Interestingly, such interactions present a promising research field in their own right, as they can reveal important insights into the relative contribution of facial and vocal information to social evaluations beyond attractiveness (see [70,71]).

People differ in how much they prioritize immediate rewards, including sociosexual opportunities, vs long-term goals; individual differences in sleep behaviors, and attitudes toward sleep, correspond with such differing priorities

Live Fast, Die Young, and Sleep Later: Life History Strategy and Human Sleep Behavior. Vahe Dishakjian, Daniel M T Fessler, Adam Maxwell Sparks. Evolution, Medicine, and Public Health, eoaa048, December 2 2020, https://doi.org/10.1093/emph/eoaa048

Abstract

Background and objectives: Life History Theory (LHT) describes trade-offs that organisms make with regard to three investment pathways: growth, maintenance, and reproduction. In light of the reparative functions of sleep, we examine sleep behaviors and corresponding attitudes as proximate manifestations of an individual’s underlying relative prioritization of short-term reproduction versus long-term maintenance.

Methodology: We collected survey data from 568 participants across two online studies having different participant pools. We use a mixture of segmented and hierarchical regression models, structural equation modeling, and machine learning to infer relationships between sleep duration/quality, attitudes about sleep, and biodemographic/psychometric measures of life history strategy (LHS).

Results: An age-mediated U- or V-shaped relationship appears when LHS is plotted against habitual sleep duration, with the fastest strategies occupying the sections of the curve with the highest mortality risk: < 6.5 hours (short sleep) and > 8.5 hours (long sleep). LH “fastness” is associated with increased sleepiness and worse overall sleep quality: delayed sleep onset latency, more wakefulness after sleep onset, higher sleep-wake instability, and greater sleep duration variability. Hedonic valuations of sleep may mediate the effects of LHS on certain sleep parameters.

Conclusions and implications: The costs of deprioritizing maintenance can be parameterized in the domain of sleep, where “life history fastness” corresponds with sleep patterns associated with greater senescence and mortality. Individual differences in sleep having significant health implications can thus be understood as components of lifelong trajectories likely stemming from calibration to developmental circumstances. Relatedly, hedonic valuations of sleep may constitute useful avenues for non-pharmacological management of chronic sleep disorders.

Lay Summary: Sleep is essential because it allows the body to repair and maintain itself. But time spent sleeping is time that cannot be spent doing other things. People differ in how much they prioritize immediate rewards, including sociosexual opportunities, versus long-term goals. In this research, we show that individual differences in sleep behaviors, and attitudes toward sleep, correspond with psychological and behavioral differences reflecting such differing priorities. Orientation toward sleep can thus be understood as part of the overall lifetime strategies that people pursue.

Keywords; sleep, hedonic, Life History Theory, somatic maintenance, evolutionary medicine


The strongest predictors of antihero affinities were aggression, Machiavellianism, and psychopathy

Greenwood, D., Ribieras, A., & Clifton, A. (2020). The dark side of antiheroes: Antisocial tendencies and affinity for morally ambiguous characters. Psychology of Popular Media, Dec 2020. https://doi.org/10.1037/ppm0000334

Rolf Degen's take: https://twitter.com/DegenRolf/status/1336560616232935426

Abstract: Antiheroes—protagonists who are often depicted as Machiavellian, narcissistic, or psychopathic (Dark Triad traits)—have garnered recent empirical attention. Research has typically focused on the mass appeal of the characters and genre rather than on individual differences that predict such appeal. The present survey study (N = 162) extends this work by examining viewers’ antisocial tendencies (Dark Triad traits, aggression, and moral disengagement) in conjunction with an affinity for antihero genres and favorite antihero characters (similarity, wishful identification, and parasocial interaction). Results show that aggression, Machiavellianism, and psychopathy were the strongest predictors of antihero affinities. Male antiheroes vastly outnumbered female antiheroes as favorite character choices, although this skew was significantly greater among male participants than female ones. No differences in antihero character affinity emerged as a function of participant gender. Finally, the degree of perceived character villainy and IMDB ratings of violence were inversely related to wishful identification and parasocial interaction with a favorite character. Findings underscore the complex ways in which viewers engage with antihero characters and genres.


How Many People Have Ever Had a Threesome?

How Many People Have Ever Had a Threesome? Justin J. Lehmiller. Psychology Today, De 8 2020. https://www.psychologytoday.com/intl/blog/the-myths-sex/202012/how-many-people-have-ever-had-threesome

Rolf Degen's take: https://twitter.com/DegenRolf/status/1336557791360782338

It’s important to note that neither of our samples was representative of the population, which means that caution is warranted in generalizing the findings broadly. Also, they don’t tell us how many people have ever had a threesome in which all participants are of the same gender. That said, there are a few important takeaways here.

First, if we want to understand attitudes toward and experiences with threesomes, we can’t just look at what college students are doing. Young adults are less interested in and experienced with threesomes, so if we want to understand who’s engaging in this behavior, why, and what their experiences are like, it is important to recruit samples that are more diverse with respect to age. 

Second, attitudes toward and experiences with MGTs (mixed-gender threesomes) appears to vary substantially according to sexual identity, with bisexual-identified persons appearing most likely to have had an MGT before. 

Finally, these findings also suggest that MGTs are not a rare or uncommon sexual practice and that sex scientists would do well to devote more attention to this understudied topic.


Check also Mixed-gender threesomes: Sexual minority individuals reported more positive outcomes than did heterosexual individuals; there is a lot of interaction with sexual minority individuals in MGTs

Exploring Variations in North American Adults’ Attitudes, Interest, Experience, and Outcomes Related to Mixed-Gender Threesomes: A Replication and Extension. Ashley E. Thompson, Allison E. Cipriano, Kimberley M. Kirkeby, Delaney Wilder & Justin J. Lehmiller. Archives of Sexual Behavior, Nov 11 2020. https://www.bipartisanalliance.com/2020/11/mixed-gender-threesomes-mgts-sexual.html


Complicated relationship between Machiavellianism and social-cognitive skill because Machiavellianism encompasses features that blend deficiency, proficiency, and average levels of social-cognitive skills

Hart, W., Breeden, C. J., & Kinrade, C. (2020). Re-conceptualizing Machiavellianism and social-cognitive skills: Machiavellianism blends deficient, proficient, and average social-cognitive skills. Journal of Individual Differences, Dec 2020. https://doi.org/10.1027/1614-0001/a000340

Abstract: Machiavellianism is presumed to encompass advanced social-cognitive skill, but research has generally suggested that Machiavellian individuals are rather deficient in social-cognitive skill. However, previous research on the matter has been limited to measures of (a) Machiavellianism that are unidimensional and saturated with both antagonism and disinhibition and measures (b) only one type of social-cognitive skill. Using a large college sample (N = 461), we examined how various dimensions of Machiavellianism relate to two types of social-cognitive skill: person-perception skill and general social prediction skill. Consistent with some prior theorizing, the planful dimension of Machiavellianism was positively related to both person-perception and general social prediction skills; antagonistic dimensions of Machiavellianism were negatively related to both skills; either agentic or cynical dimensions of Machiavellianism were generally unrelated to both skills. Overall, the current evidence suggests a complicated relationship between Machiavellianism and social-cognitive skill because Machiavellianism encompasses features that blend deficiency, proficiency, and average levels of social-cognitive skills.