Thursday, November 5, 2020

Hippocampal Volume and Navigational Ability: The Map(ping) Is Not to Scale

Weisberg, Steven M., and Arne Ekstrom. 2020. “Hippocampal Volume and Navigational Ability: The Map(ping) Is Not to Scale.” PsyArXiv. November 5. doi:10.31234/

Rolf Degen's take:

Abstract: A critical question regards the neural basis of complex cognitive skill acquisition. One extensively studied skill is navigation, with evidence suggesting that humans vary widely in navigation abilities. Yet, data supporting the neural underpinning of these individual differences are mixed. Some evidence suggests robust structure-function relations between hippocampal volume and navigation ability, whereas other experiments show no such correlation. We focus on several possibilities for these discrepancies: 1) volumetric hippocampal changes are relevant only at the extreme ranges of navigational abilities; 2) hippocampal volume correlates across individuals but only for specific measures of navigation skill; 3) hippocampal volume itself does not correlate with navigation skill acquisition; connectivity patterns are more relevant. To explore this third possibility, we present a model emphasizing functional connectivity changes, particularly to extra-hippocampal structures. This class of models arises from the premise that navigation is dynamic and that good navigators flexibly solve spatial challenges. These models pave the way for research on other skills and provide more precise predictions for the neural basis of skill acquisition.

How the COVID‐19 pandemic has changed our lives: A study of psychological correlates across 59 countries

How the COVID‐19 pandemic has changed our lives: A study of psychological correlates across 59 countries. Elisabet Alzueta  Paul Perrin  Fiona C. Baker  Sendy Caffarra  Daniela Ramos‐Usuga  Dilara Yuksel  Juan Carlos Arango‐Lasprilla. Journal of Clinical Psychology, October 31 2020.

Rolf Degen's take:


Objective: This study examined the impact of the COVID‐19 pandemic and subsequent social restrictions or quarantines on the mental health of the global adult population.

Method: A sample of 6,882 individuals (Mage = 42.30; 78.8% female) from 59 countries completed an online survey asking about several pandemic‐related changes in life and psychological status.

Results: Of these participants, 25.4% and 19.5% reported moderate‐to‐severe depression (DASS‐21) and anxiety symptoms (GAD‐7), respectively. Demographic characteristics (e.g. higher‐income country), COVID‐19 exposure (e.g., having had unconfirmed COVID‐19 symptoms), government‐imposed quarantine level, and COVID‐19‐based life changes (e.g., having a hard time transitioning to working from home; increase in verbal arguments or conflict with other adult in home) explained 17.9% of the variance in depression and 21.5% in anxiety symptoms.

Conclusions: In addition to posing a high risk to physical health, the COVID‐19 pandemic has robustly affected global mental health, so it is essential to ensure that mental health services reach individuals showing pandemic‐related depression and anxiety symptoms.


This study examined the effects of the COVID‐19 pandemic on the mental health of adults in the general population of five global regions, as well as the demographic risk factors that may have made depression and anxiety symptoms more likely. This is one of the first studies to provide a global perspective on the pandemic's effects on mental health. While the majority of the sample had low or mild levels of depression and anxiety symptoms during the pandemic, a significant proportion of respondents reported moderate to severe symptoms of depression (25.4%) and anxiety (19.5%). These prevalence rates help generalize to a much larger global population the high rates of mental health issues found in previous studies of specific global regions or countries (Solomou & Constantinidou, 2020). COVID‐19‐related life changes were the strongest predictors of higher depression and anxiety symptoms over and above effects of demographics, quarantine level, and COVID‐19 exposure. Myriad consequences of the pandemic, including challenges paying bills, inability to access food, conflict in the home, and separation from loved ones were linked with poorer mental health.

In line with the current results, emerging studies have consistently reported a high prevalence of depression and anxiety symptoms in populations around the world during the COVID‐19 pandemic (Ahmed et al., 2020; Gao et al., 2020; Li et al., 2020; Mazza et al., 2020; Moghanibashi‐Mansourieh, 2020, Solomou & Constantinidou, 2020; Ueda et al., 2020; Wang, Wang, et al., 2020). While most of these cross‐sectional studies—including the current study—can only show levels of and not change in depression and anxiety symptoms in the populations studied during the pandemic, a cross‐sectional study in China (Ahmed et al., 2020) comparing the psychological impact during the outbreak with an epidemiological study conducted before the pandemic (Huang et al., 2019) concluded that the rates of anxiety, depression, and alcohol consumption were higher, and mental well‐being was lower, among Chinese people during the COVID‐19 outbreak than before. In addition, a longitudinal study comparing pre‐ and during‐pandemic levels of depression, anxiety, and well‐being in two UK population cohorts reported a significant decrease in well‐being and a higher probability of anxiety disorders during the pandemic (24% in vs. the previous 13%; Kwong et al., 2020). Altogether, evidence so far points to the pandemic's negative effect on mental health.

Certain populations may be more vulnerable to the impact of the COVID‐19 pandemic on mental health. In line with previous studies (Kwong et al., 2020; Mazza et al., 2020; Moghanibashi‐Mansourieh, 2020; Solomou & Constantinidou; 2020; Stanton et al., 2020; Wang, Wang, et al., 2020), the current study found a higher prevalence of depression and anxiety symptoms among women or people with a nonbinary/transgender relative to men. These findings also are consistent with the literature showing a strong association between woman gender and a higher prevalence of anxiety and depression in the general population in nonpandemic times (Baxter et al., 2014; Kessler, 2003), suggesting gender‐role influences on coping with or reporting of mental health symptoms (Mrazek, and Haggerty, 1994; Sandanger et al., 2004). This somewhat consistent finding is complex, and researchers and theorists have postulated many explanations for it, ranging from social norms for the gender‐role based experience of emotion, to personality traits, to hormones (Albert, 2015). Whatever the source of these effects, the current findings suggest that women and nonbinary‐trans individuals may be at greater risk for mental health symptoms during the pandemic.

The current study found other demographic factors, such as younger age, not being partnered, and living in a high‐income country to be associated with higher levels of depression and anxiety symptoms during the pandemic. In terms of age, others researchers have reported that younger adults may be more vulnerable to the effects of the COVID‐19 pandemic (Moghanibashi‐Mansourieh, 2020; Qiu et al., 2020; Stanton et al., 2020), which could be a consequence of greater exposure to media, how they are affected by financial crisis, and managing workload responsibilities (Ahmed et al., 2020; Liu et al., 2020). Also, studies about previous outbreaks have attributed the greater vulnerability of young people to a less effective use of coping strategies than older adults (Yeung & Fung, 2007). The current finding that being not partnered was associated with more depression and anxiety symptoms supports findings in the general population that being separated or divorced are risk factors for some psychological disorders (Afifi et al., 2006; Andrade et al., 2003).

The finding that living in a high‐income country during the pandemic is a risk factor for depression and anxiety might seem counterintuitive, though it is in line with studies showing that citizens of these countries report more stress relative to those in low‐to‐middle income countries (Br et al., 2011). A related (and likely overlapping) finding was that countries belonging to the Latin America and Caribbean cluster showed a lower prevalence of mental health symptoms compared to countries belonging to North America, Europe and Central Asia, and Sub‐Saharan Africa clusters. Comparing psychological symptoms across different cultures and countries presents complex challenges (Van Bavel et al., 2020), and therefore these findings should be interpreted with caution. However, differences found in symptoms across global regions might in part be explained by the timing of data collection. The COVID‐19 pandemic outbreak has evolved rapidly and asynchronously across countries. At the time of data collection, the outbreak was more severe in North America, Europe, and Central Asia in comparison to the Latin America and Caribbean region (see report from World Health Organization, 2020). Prevalence studies during the pandemic have shown the severity of psychological symptoms are especially high in areas most affected by COVID‐19 (Moghanibashi‐Mansourieh, 2020; Solomou & Constantinidou, 2020). Therefore, lower levels of depression and anxiety reported in global regions might be explained by a possible lower perception of COVID‐19 severity or threat.

The main finding of this study is that even though certain demographic characteristics and COVID‐19 exposure were associated with increased symptoms of depression and anxiety, the effects that COVID‐19 had on a person's life were generally the most robust predictors of negative psychological effects. The most notable effects included the impact that the COVID‐19 pandemic had on economic stability (i.e., being unable to get enough food or healthy food, being unable to pay important bills like rent or utilities), work (i.e., having a hard time doing one's job well because of needing to take care of people in the home, having a hard time making the transition to working from home), and social aspects (i.e., being separated from family or close friends, having an increase in verbal arguments or conflict with other adults in home). Somewhat surprisingly, level of quarantine or social restrictions issued by governments at the time of data collection was not a notable predictor of depression and anxiety symptoms. Thus, depression and anxiety in the current sample were not directly accounted for by governmental restrictions but rather likely the consequences of these restrictions and the pandemic as a whole on participants’ lives. Studies from prior epidemics have shown that social isolation during a quarantine period is commonly associated with anxiety and depression symptoms (DiGiovanni et al., 2004; Hawryluck et al., 2004). Also, comparing data from a quarantined population versus no‐quarantined population during the COVID‐19 outbreak in China (n = 1593), a study reported a higher prevalence of depression (22.4% vs 11.9%) and anxiety (12.9% vs 6.7%) in the quarantined group (Lei et al., 2020).

The specific unique effects found within the regression provide evidence that COVID‐19‐related life changes, especially in home and work spheres, were associated with increased depression and anxiety symptoms. Changes in family structure and roles can cause psychological distress, ultimately affecting the relational environment at home (Prime et al., 2020). In this sense, caregivers who must adapt their work routines to care for others at home are at a higher risk of burden. In addition, results from the present study show that verbal arguments or conflicts with others at home during the confinement were very strongly associated with depression and anxiety symptoms. A previously problematic family environment combined with financial strain and social isolation—both well‐known domestic abuse risk factors (Usher et al., 2020)—might lead to escalating conflicts and violence at home during confinement. Indeed, there has been an unprecedented wave of intimate partner violence during the COVID‐19 pandemic (Campbell 2020). Economic insecurity, increase exposure to possible abusive relationships, as well as limited access to support in the community, among others, have been related to intimate partner violence during the COVID‐19 pandemic (Peterman et al. 2020). Therefore, providing accessible mental health support to vulnerable families while confined is critical.

Findings presented here need to be interpreted in the context of several study limitations. First, the ongoing COVID‐19 pandemic is a volatile phenomenon affecting countries in different ways. This cross‐sectional study represents the effects of the pandemic on an adult population in several global regions during a specific period of time (April–May 2020), and therefore, different countries and even different regions within a country were experiencing different scenarios in relation to the pandemic. However, it is important to note that many of the countries were experiencing a prominent peak in the COVID‐19 pandemic, and all participants’ countries were under some kind of social isolation measures at the time of data collection. Also, with the cross‐sectional design, it is not possible to conclude directionality of the relationships found, and people with poor mental health also could have reported worse life changes based on depression‐ or anxiety‐driven viewpoints. In addition, even while much effort was made to achieve a generalizable global sample, the representation of countries in different global regions or of specific demographic characteristics was not equal. Therefore, comparisons between global regions, and generalizability to the entire global population, must be viewed with caution. Certain global regions (e.g., North America, Europe) had a much higher representation than other regions (e.g., Asia, Africa) due to limitations in the snowball data collection approach and languages used. Due to the high representation of women in the sample, a finding commonly observed in other psychological studies (Plomecka et al., 2020; Solomou & Constantinidou, 2020), generalizations to men also should be made with an appropriate degree of caution.

Dreams: Deep neural networks face the issue of overfitting as they learn (performance on one data set increases but the network's performance fails to generalize); dreams can be the "noise injections" in the form of corrupted inputs

The Overfitted Brain: Dreams evolved to assist generalization. Erik Hoel., Sep 24 2020. arXiv:2007.09560

Abstract: Understanding of the evolved biological function of sleep has advanced considerably in the past decade. However, no equivalent understanding of dreams has emerged. Contemporary neuroscientific theories generally view dreams as epiphenomena, and the few proposals for their biological function are contradicted by the phenomenology of dreams themselves. Now, the recent advent of deep neural networks (DNNs) has finally provided the novel conceptual framework within which to understand the evolved function of dreams. Notably, all DNNs face the issue of overfitting as they learn, which is when performance on one data set increases but the network's performance fails to generalize (often measured by the divergence of performance on training vs. testing data sets). This ubiquitous problem in DNNs is often solved by modelers via "noise injections" in the form of noisy or corrupted inputs. The goal of this paper is to argue that the brain faces a similar challenge of overfitting, and that nightly dreams evolved to combat the brain's overfitting during its daily learning. That is, dreams are a biological mechanism for increasing generalizability via the creation of corrupted sensory inputs from stochastic activity across the hierarchy of neural structures. Sleep loss, specifically dream loss, leads to an overfitted brain that can still memorize and learn but fails to generalize appropriately. Herein this "overfitted brain hypothesis" is explicitly developed and then compared and contrasted with existing contemporary neuroscientific theories of dreams. Existing evidence for the hypothesis is surveyed within both neuroscience and deep learning, and a set of testable predictions are put forward that can be pursued both in vivo and in silico.

Women were more likely to baby talk to their dog and speak gently/whisper to their dog, while young adults were more likely to use collar correction/jerk the leash

Owner Sex and Human–Canine Interactions at the Park. Shelly Volsche et al. Anthrozoös, Volume 33, 2020 - Issue 6, Pages 775-785. Nov 4 2020.

Rolf Degen's take:

Abstract: The purpose of this exploratory study was to investigate if and what types of differences exist between men and women when interacting with their dogs in a “natural” setting. In the case of this study, we defined “natural” as visiting a public park with their dog. To do this, we completed a series of 10-minute focal follows (n = 177) on human–canine dyads at local leashed and off-leash dog parks from December 2018 to March 2019. Data collection included counting incidences of 14 specific interactions (i.e., “baby talks to dog” or “scolds/speaks harshly to dog”), observable demographics (sex of owner, age cohort, sex of dog), and additional notes (i.e., extended play sessions, talking to other park visitors, cell phone use). Women were more likely to baby talk to their dog and speak gently/whisper to their dog, while young adults were more likely to use collar correction/jerk the leash. The results also suggest young adults may be more likely to throw toys/play with their dog, though more data are needed to confirm this. Given the increase in invested pet dog ownership, we suggest that sex differences in interactions with pet dogs mirror the literature on sex differences in human parenting. This is particularly relevant as decreasing birth rates and climbing pet ownership give rise to the practice of applying parenting strategies to pets, suggesting the need to better understand potential welfare concerns that may mirror those in the parenting literature.

Keywords: age, dogs, focal follows, human–animal interaction, pet parenting, sex

Women’s productivity responds more to wage increses and their turnover responds less to wage changes than men’s, which can lead to occupational pay gaps

The Payoffs Of Higher Pay: Elasticities Of Productivity And Labor Supply With Respect To Wages. Natalia Emanuel · Emma Harrington (Job Market Paper). November 3, 2020.

Abstract: When setting pay, firms trade off the potential benefits of higher compensation—including increased productivity, decreased turnover, and enhanced recruitment—against their direct costs. We estimate productivity and labor supply elasticities with respect to wages among warehouse and call-center workers in a Fortune 500 retailer. To identify these elasticities, we use rigidities in the firm’s compensation policies that create plausibly exogenous variation relative to local outside options, as well as discrete jumps when the firm adjusts pay. We document labor market frictions that give firms wage-setting power: we estimate moderately large, but finite, turnover elasticities (−3.0 to −4.5) and recruitment elasticities (3.2 to 4.2). The firm gains $1.10 from increased productivity for a $1 increase in wages. By comparing warehouse workers’ responses to higher wages both across and within workers, we estimate that over half of the turnover reductions and productivity increases arise from behavioral responses as opposed to compositional differences. These aggregate patterns mask considerable heterogeneity by gender: women’s productivity responds more and their turnover responds less to wage changes than men’s, which can lead to occupational pay gaps.

Check also... Bus and Train Operators: Men actually work nearly 50% more overtime hours than women, who are less likely than men to game the scheduling system by trading off work hours at regular wages for overtime hours at premium wages:

Bolotnyy V, Emanuel N. Why Do Women Earn Less Than Men? Evidence from Bus and Train Operators (Job Market Paper). Working Paper.

Album and song sales have a remarkably short period of economic viability. Sales of whole albums approach zero by the end of their first year of release; individual tracks maintain meaningful sales volumes for longer

Copyright and Economic Viability: Evidence from the Music Industry. Kristelia García  James Hicks  Justin McCrary. Journal of Empirical Legal Studies, November 5 2020.

Rolf Degen's take:

Abstract: Copyright provides a long term of legal excludability, ostensibly to encourage the production of new creative works. How long this term should last, and the extent to which current law aligns with the economic incentives of copyright owners, has been the subject of vigorous theoretical debate. We investigate the economic viability of content in a major content industry—commercial music—using a novel longitudinal dataset of weekly sales and streaming counts. We find that the typical sound recording has an extremely short commercial half‐life—on the order of months, rather than years or decades—but also see evidence that subscription streaming services are extending this period of economic viability. Strikingly, though, we find that decay rates are sharp even for blockbuster songs, and that the patterns persist when we approximate weekly revenue. Although our results do not provide an estimate of the causal effect of copyright on incentives, they do put bounds on the problem, suggesting a misalignment between the economic realities of the music industry and the current life‐plus‐70 copyright term.


Our top‐line results show that album and song sales have a remarkably short period of economic viability. Sales of whole albums (both traditional CDs and digital) approach zero by the end of their first year of release. Individual tracks maintain meaningful sales volumes for longer—perhaps up to several years—but average track sales are negligible in the medium term, and almost zero by the end of our 10‐year study period.

We also find indicative evidence that streaming services prolong the life of sound recordings. Our data suggest that the economic value of the average track declines more slowly through this medium. (From a revenue perspective, the incentive implications of this remain unclear, since streaming volume far exceeds sales volume, while per‐sale earnings far exceed per‐stream royalties.) Unfortunately, our conclusions about streaming are quite tentative. As a result of the small sample size and limited window of observation, we simply cannot make confident inferences. This is a clear avenue for further research as the music industry continues to evolve and further data on consumer behavior becomes available.

There are obvious limitations to our analysis. First, the findings are purely descriptive: nothing in our data allows us to directly assess the causal effect of copyright on sales, let alone on creators’ or labels’ incentives. The data provide a portrait of the economic environment faced by the industry, but we cannot directly observe the choices of artists and record labels.

Second, this is just a piece of the puzzle. Although music is a copyright‐intensive industry, consumer sales and streams are only one component of revenues for commercial music. Statutory royalties paid to the owners of musical compositions and sound recordings are not accounted for in our data. Nor are the various contractual income sources—including sync licensing, touring, and endorsements—that can constitute a significant portion of an artist's revenues. In many cases, these contractual revenue streams are influenced by the copyright‐related revenue streams. This impact varies, however, from artist to artist, and over the course of a career. Unfortunately, our results cannot reveal much quantitatively about these ancillary revenue sources because this information is not generally public.31 Nevertheless, we think these data provide a reasonably good proxy for the overall popularity and revenue performance of the bulk of commercially recorded music.

Our analysis shows that the average work has exhausted its commercial potential long before the term of copyright protection expires. This might suggest—as we conclude—an inefficiency owing to overprotection, such that a more carefully calibrated term would strike a better balance between incentivizing creation and ensuring a robust public domain. An alternate interpretation might suggest that a work's lack of commercial value mitigates concerns stemming from overprotection. In other words, if a work is commercially worthless, what harm is there in that work remaining under copyright protection? In a word: access. In the absence of a use requirement, copyright protection prevents a work from falling into the public domain regardless of whether the rightsholder is actively exploiting it or making it available. The literature has identified several categories of post‐commercial works for which an extended period of copyright protection has an adverse impact on access. These include orphan works (works whose authors are either unknown or unidentifiable); mismanaged works (where a work's author is known but deceased, and the stewards are either delinquent or difficult to trace); and works by disadvantaged or marginalized authors. Works in the latter category, for example, often do not experience commercial success in their day, but may later prove to be valuable historical accounts of oppression (Reese 2012: 291).

Overall, we find the sharpness of the results quite striking. Our analysis provides a baseline for the commercial relevance of the typical sound recording and offers a rare window into the on‐the‐ground economics of a major content industry. As political debates about the appropriate term of copyright continue to roil in the international arena, empirical evidence provides an important, but inexplicably rare, check: Our findings suggest that current copyright terms are at odds with the economic reality of the majority of commercially recorded music.

Experiencing an object as pleasurable is a prerequisite for judging it to be beautiful; but to qualify as beautiful, an object must elicit especially high levels of pleasure & be matched to internal learned models of what counts as beautiful

The nature of beauty: behavior, cognition, and neurobiology. Martin Skov  Marcos Nadal. Annals of the New York Academy of Sciences, November 4 2020.

Rolf Degen's take:

Abstract: Beauty is commonly used to refer to positive evaluative appraisals that are uniquely human. Little is known, however, about what distinguishes beauty in terms of psychological function or neurobiological mechanisms. Our review describes recent empirical studies and synthesizes what behavioral, cognitive, and neuroscientific experiments have revealed about the nature of beauty. These findings suggest that beauty shares computational mechanisms with other forms of hedonic appraisal of sensory objects but is distinguished by specific conceptual expectations. Specifically, experiencing an object as pleasurable is a prerequisite for judging it to be beautiful; but to qualify as beautiful, an object must elicit especially high levels of pleasure and be matched to internal learned models of what counts as beautiful. We discuss how these empirical findings contradict several assumptions about beauty, including the notion that beauty is disinterested, and that it is specific to Homo sapiens.

Denmark: Citizens' policy opinions changed immediately and substantially when their party switched its policy position—even when the new position went against citizens' previously held views

How Political Parties Shape Public Opinion in the Real World. Rune Slothuus  Martin Bisgaard. American Journal of Political Science, November 4 2020.

Rolf Degen's take:

Abstract: How powerful are political parties in shaping citizens' opinions? Despite long‐standing interest in the flow of influence between partisan elites and citizens, few studies to date examine how citizens react when their party changes its position on a major issue in the real world. We present a rare quasi‐experimental panel study of how citizens responded when their political party suddenly reversed its position on two major and salient welfare issues in Denmark. With a five‐wave panel survey collected just around these two events, we show that citizens' policy opinions changed immediately and substantially when their party switched its policy position—even when the new position went against citizens' previously held views. These findings advance the current, largely experimental literature on partisan elite influence.

Using Twitter decreases the level of depressive symptoms by 27%, which explains why social media usage in the US has grown steadily even though most studies find that more usage correlates with higher depressive symptoms

Social Media Usage and the Level of Depressive Symptoms in the United States. Qin Jiang. October 30, 2020.

Abstract: In 2019, more than 72% of US adults used social media. The use of social media can potentially decrease the level of depressive symptoms by providing support or increase the level of depressive symptoms by putting social pressure on users. This paper leverages a fixed effects model to estimate the effect of using social media platforms on depression. I find that using Twitter decreases the level of depressive symptoms by 27%. This result explains why social media usage in the US has grown steadily even though most studies find that more usage correlates with higher levels of depressive symptoms. There is heterogeneity with respect to age, income, education, race, previous level of depressive symptoms, and region. The average labor market benefit that comes from this effect is equivalent to 0.1% GDP in the US.

JEL: I12, I31, O33

Keywords: Social Media, Depressive Symptoms, Twitter, CESD, Fixed Effects