Monday, January 13, 2020

If you were to force America's 11 largest cities to be no larger than Miami, real income per American would fall by 7.9%; if planning regulations were lifted entirely, real income would rise by 25.7%

Urban Growth and its Aggregate Implications. Gilles Duranton, Diego Puga. NBER Working Paper No. 26591, December 2019.

We develop an urban growth model where human capital spillovers foster entrepreneurship and learning in heterogenous cities. Incumbent residents limit city expansion through planning regulations so that commuting and housing costs do not outweigh productivity gains. The model builds on strong microfoundations, matches key regularities at the city and economy-wide levels, and generates novel predictions for which we provide evidence. It can be quantified relying on few parameters, provides a basis to estimate the main ones, and remains transparent regarding its mechanisms. We examine various counterfactuals to assess quantitatively the effect of cities on economic growth and aggregate income.

1. If you restricted New York City and Los Angeles to the size of Chicago, 18.9 million people would be displaced and per capita rural income would fall by 3.6%, due to diminishing returns to labor in less heavily populated areas.

2. The average reduction in real income per person, from this thought experiment, would be 3.4%.  You will note that NIMBY policies are in fact running a version of this policy, albeit at different margins and with a different default status quo point.

3. If you were to force America's 11 largest cities to be no larger than Miami, real income per American would fall by 7.9%.

4. If planning regulations were lifted entirely, NYC would reach about 40 million people, Philadelphia 38 million (that's a lot of objectionable sports fans!), and Boston just shy of 30 million (ditto).

5. Output per person, under that scenario, would rise in NYC by 5.7% and by 13.3% in Boston.  That said, under this same scenario incumbent New Yorkers would see net real consumption losses of 13%, whereas for Boston the incumbent losses are only about 1.1%.

6. The big winners are the new entrants.  On average, real income would rise by 25.7%.

7. Alternatively, in their model, rather than laissez-faire, if America's three most productive cities relaxed their planning regulations to the same level as the median U.S. city, real per capita income would rise by about 8.2%.

8. In all of these cases the authors calculate the change in rural per capita income, based on resulting population reallocations.

The better people are educated, the less positive their other-perceptions are; a potential explanation could be that a good education goes along with a sense of self-importance & haughtiness

Seeing the Best or Worst in Others: A Measure of Generalized Other-Perceptions. Richard Rau, Wiebke Nestler, Michael Dufner, Steffen Nestler. Assessment (to be published), January 2020. DOI: 10.13140/RG.2.2.16925.87521

Abstract: How positively or negatively people generally view others is key for understanding personality, social behavior, and psychopathology. Previous research has measured generalized other-perceptions by relying on either explicit self-reports or judgments made in group settings. With the current research, we overcome the limitations of these past approaches by introducing a novel measurement instrument for generalized other-perceptions: the Online-Tool for Assessing Perceiver Effects (O-TAPE). By assessing perceivers’ first impressions of a standardized set of target people displayed in social network profiles or short video sequences, the O-TAPE captures individual differences in the positivity of other-perceptions. In Study 1 (n = 219), the instrument demonstrated good psychometric properties and correlations with related constructs. Study 2 (n = 142) replicated these findings and also showed that the O-TAPE predicted other-perceptions in a naturalistic group setting. Study 3 (n = 200) refined the nomological network of the construct and demonstrated that the OTAPE is invulnerable to effects of social desirability.

Keywords: generalized other-perception, perceiver effect, interpersonal perception, person judgment, positivity bias

General Discussion

In the current research, we introduced the O-TAPE, a measurement tool that
objectively and reliably captures individual differences in the positivity of generalized other-perceptions. We developed two versions of the tool that use different types of stimuli:
screenshots of social network profiles (SoN-TAPE) and short video sequences (ViS-TAPE).
In both versions, perceivers differed considerably in how they judged a standardized set of
individuals, and these perceiver differences could be aggregated into a score with excellent
internal consistency, reflecting the positivity in judgments made across different targets and
traits. Further, in Studies 1 and 2 the two instruments demonstrated good convergent validity
and showed remarkable retest reliability when we administered parallel forms in a time
interval of one to three weeks. Moreover, the O-TAPE was able to predict generalized
other-perceptions in a real-life context in Study 2.
The nomological network analyses established robust convergent and divergent
relationships with a number of individual difference constructs across two heterogenous
online samples (Studies 1 and 3) and a student sample (Study 2). Most notably, more positive
generalized other-perceptions were associated with several interpersonally relevant
personality characteristics such as high communion, high agreeableness, high honestyhumility, low dispositional contempt, and (albeit less consistently) narcissistic rivalry. This
suggests that generally positive vs. negative views of others underlie many personality traits
tapping differences on the continuum from communal/prosocial to antagonistic/antisocial.
Further, some demographic variables (i.e., gender and education) were associated with
generalized other-perceptions. The gender effect converges with previous research reporting
more positive generalized other-perceptions among women (Srivastava et al., 2010; Winquist
et al., 1998; Wood et al., 2010) and indicates that women might be more mellow in their
social judgments. The education effect indicates that the better people are educated, the less
positive their other-perceptions are. A potential explanation could be that a good education
goes along with a sense of self-importance and haughtiness, but this explanation is speculative
and might be addressed in future research. Other characteristics such as openness to
experience, conscientiousness, height, explicit anthropologic beliefs, and psychological
adjustment were not or were not consistently linked to generalized other-perceptions. Finally,
the O-TAPE predicted how positively or negatively students viewed their future classmates
when they met them for the first time on a welcoming day at their university in Study 2. This
suggests that the O-TAPE captures generalized other-perceptions in an ecologically valid
way. Importantly, we ruled out the possibility that the correlations were driven by general
scale-use bias. Thus, the results are informative, specifically about the positivity in
generalized other-perceptions rather than about a global tendency to provide rather positive or
negative evaluations on rating scales in general. Finally, we also demonstrated that O-TAPE
scores are unaffected by differences in socially desirable responding.

Applications and Adaptations of the O-TAPE

Which version of the O-TAPE should be applied? The results of Study 1 and 2 suggest
that neither version should be preferred on the basis of psychometric properties. However, it
might be wise to use the ViS-TAPE rather than the SoN-TAPE when studying populations
that are not familiar with online social networks (e.g., elderly people). Yet, in most other
contexts, it might be advisable to use the SoN-TAPE rather than the ViS-TAPE for pragmatic
reasons. Specifically, the material of the SoN-TAPE can be adjusted for other languages and
the technical implementation of images into online survey platforms is usually easier than the
implementation of videos. For these reasons, we only administered the SoN-TAPE in Study 3.
There, completing the measure took most participants between five and eight minutes
(interquartile range), suggesting that researchers can draw on it even when there are time
Moreover, the clear unidimensional factor structure of trait perceiver effects and the
high internal consistency of positivity scores suggest that it would not be problematic to
reduce the number of traits rated per target in future studies in order to obtain an even shorter
instrument that still warrants a highly reliable and valid measurement of generalized other-perceptions. For this purpose, assessing impressions of at least five (sufficiently evaluative)
traits should be adequate. In order to establish unidimensionality, samples sizes should be 200
or larger. At the same time, we advise against reducing the number of rated targets given that
large target heterogeneity is crucial to warrant the generality of the measured construct.
Importantly also, Study 3 emphasized that solely assessing people’s perceptions of “a typical
person” without providing actual target stimuli does not do the job.
Researchers who are interested in applying and adapting the O-TAPE are referred to
the Open Science Framework ( There, we provide all materials
necessary to apply the O-TAPE as well as templates and instructions for adjusting the social
network stimuli for the use in non-German speaking countries.
Finally, results of Study 1 and 2 showed that generalized other-perceptions as
measured with the O-TAPE exhibit moderate yet significant overlap with scale-use bias as
measured with the ORT. However, this did not substantially affect the validity correlations in
the present work because most validation measures were themselves relatively insusceptible
to individual differences in scale-use. We thus refrained from including the ORT in Study 3.
Nevertheless, researchers might consider complementing the O-TAPE with the ORT when
they have a specific reason to suspect that scale-use bias might impair the validity of their
How should O-TAPE raw data be aggregated to obtain a scale score for each
participant? In most cases of substantive research, it will not be necessary to run random
effects models and report ICCs. As long as the only goal is to capture generalized other-perceptions, it is justified to treat the ten target stimuli as if they were items in a questionnaire
without examining how much of the overall variance is due to differences in participants vs.
differences in “item difficulties” (i.e., targets). It is also warranted to treat the rating
dimensions as if they were subscales of a questionnaire in which subscale scores can be
averaged to index an overall construct (i.e., positivity). Reporting Cronbach’s coefficient
alpha across these “subscales” serves as a straightforward (and conservative) estimate of the
positivity score’s reliability.

Humans judge faces in incomplete photographs as physically more attractive

Humans judge faces in incomplete photographs as physically more attractive. Diana Orghian & C├ęsar A. Hidalgo. Scientific Reports volume 10, Article number: 110 (Jan 2020).

Abstract: Attractive people are perceived to be healthier, wealthier, and more sociable. Yet, people often judge the attractiveness of others based on incomplete and inaccurate facial information. Here, we test the hypothesis that people fill in the missing information with positive inferences when judging others’ facial beauty. To test this hypothesis, we conducted seven experiments where participants judged the attractiveness of human faces in complete and incomplete photographs. Our data shows that—relative to complete photographs—participants judge faces in incomplete photographs as physically more attractive. This positivity bias is replicated for different types of incompleteness; is mostly specific to aesthetic judgments; is stronger for male participants; is specific to human faces when compared to pets, flowers, and landscapes; seems to involve a holistic processing; and is stronger for atypical faces. These findings contribute to our understanding of how people perceive and make inferences about others’ beauty.


We often judge others based on their physical appearance. Such judgments are driven by inferential mechanisms that help us fill in missing information. Here, we showed that (i) the inferential mechanism that we use to judge the physical appearance of human faces is positively biased, (ii) the bias is more pronounced in male participants, (iii) is specific to aesthetic judgments, but generalizes to other dimensions when the bias is strong enough, (iv) seems to be specific to human faces when compared to dog faces, landscapes, and flowers, and (v) is driven by the use of a holistic representation of what is a typical/average face. We also ruled out similarity to the self, positive expectations, and mood differences as explanatory mechanisms for the effect.
Presented with an incomplete human faces and instructed to judge their attractiveness, participants resort to what they know about faces (structure and features) and their representation of a prototypical face to generate new holistic representations. An inferential process that stems from matching the type of stimuli – i.e., human faces – with a prototype already existent in their memories. While incomplete human faces lead to an overall positive bias effect, stimuli such landscapes, pets, and flowers showed not positivity bias, which is likely due to the absence of a clear prototypical representations of these stimuli in people’s memories. Although our experiments suggest that typicality may have a role in the attractiveness positivity effect, further and more direct evidence is necessary to prove the robustness of this relationship. If typicality does play a relevant role, is also important to better understand how is this prototypical representation created and what are exactly the past experiences that shape it.
While the hypothesis that people fill in the missing pieces with positive inferences was never explicitly raised and tested, Saegusa and Watanabe stumbled on similar findings while investigating other phenomena. In their research on how information from individual facial parts contributes to the judgements of whole-face attractiveness over time, they found that attractiveness was higher for independent facial parts (e.g., eye, mouth) than for whole-faces36. Another study found that, on average, back-view photographs were rated as more attractive than front-view photographs37. The back-view condition can be seen as an extreme case of our incomplete treatments, in which the only information provided about the person is the shape of the head and the hair type, color, cut, and length. On a similar note, Miyazaki and Kawahara38 in an attempt to look into how the use of sanitary-masks by the Japanese women affects people’s perception of their beauty and health, found that certain types of occlusions also lead to higher perceived attractiveness, but only for originally unattractive faces judgements. Finally, Lu and collaborators39 manipulated the amount of information and attractiveness of cartoon characters (computer generated, gouache, and stick-figures), with the purpose of studying gender difference in attractiveness judgements. However, no significant differences were found between attractiveness judgements of the three types of cartoons. Overall, these findings support our hypothesis: when perceiving incomplete faces people fill in the missing information with positive details. Also, noteworthy, but in a domain different from that of facial perception, the work by Norton and colleagues8 showed that people perceive others’ personalities more favorably when they are provided with fewer personality traits as opposed to many.
Being positively biased about the attractiveness of strangers might have been a mechanism evolutionarily selected, as it might have facilitated social and reproductive events. However, the impact of this bias might only apply to impressions and interactions in first encounters. It is known that first impressions get diluted as we get to know and acquire more information about a person7. Thus, an interesting question for future research is the influence of the positivity bias on subsequent interactions with the target-person.
Whether the effect is unique to human faces also requires further research. More homogeneous categories than the ones we used need to be submitted to the same analysis to reach a more robust conclusion regarding the specificity of the positivity bias effect.
The contribution of face symmetry should also be studies in more detail. A meta-analysis performed by Rhodes in 200640 tells us that symmetric faces are perceived as more attractive when they result from blending the original and mirror-reversed images, but they are not when they are “chimeras” (pure mirror-reversed with no blending). Pure mirror-reversed photographs lead to less attractive exemplars due to enlargement or reduction of the mid-line features41. In our second experiment, we used chimeras because we wanted to understand if one half of the face is used to infer the missing half, but it would be interesting to test whether using a blended symmetric face (and thus more naturally looking) would lead to a similar conclusion.
One limitation of our work is that all experiments were performed online with Mechanical Turk participants. While there is research showing that data from online experiments is comparable to data from lab-based experiments42,43, these conclusions need to be replicated in the laboratory and in contexts where the implications of the research might be directly relevant (e.g., social media, recruitment, fashion industry, entertainment, advertisement, and marketing).

We aim to determine whether shoes are a systematic form of self-expression

Those shoes are you! Personality expressed in shoes. Stephanus Badenhorst et al. Univ. of Wisconsin, Jan 2020.

• People express their personality traits and attitudes in many ways. People express themselves
in the way they speak and carry themselves1, what they post on social media2, the leisure activities they pursue3, the music they prefer4, and even the clothes they wear5.
• We aim to determine whether shoes are a systematic form of self-expression. Only one other
research team has pursued this question 6; in that study, men and women completed a brief (10-item) personality inventory and submitted a photo of the shoes they wear most often. The researchers showed that characteristics of people’s shoes are tied to their gender (more feminine shoes) and income (more expensive shoes), but they found very few links between people’s personality traits and shoe characteristics.
• In the current study, we extend past research by (1) using a comprehensive personality inventory, (2) asking participants to report on their shoe purchasing and decision-making behaviors, and (3) asking participants to submit a photo of the shoes they think best represents their personality.
• In this poster, we present the results of analyses designed to test two hypotheses:
(1) The shoes that people wear are tied to their personality (e.g., more conscientious people wear
cleaner and well-maintained shoes); and
(2) People’s shoe-buying and shoe-decision-making behaviors are tied to their personality traits (e.g., more extraverted people own more shoes and spend more money on their shoes).
• As far as we know, we are only the second research team to test the hypothesis that people drop hints about their personality through the shoes they wear; further, we are the first team to investigate how people’s shoe decision-making and shoe consumer habits relate to their personality traits.
• Not all personality traits were correlated with all shoe characteristics, and the correlations that were statistically significant were generally weak in magnitude. However, we had a lot of shoes that did not vary from each other: 3 people uploaded a basic Converse, 15 people uploaded a black or neutral toned running shoe, and 4 people uploaded a basic white Vans canvas loafer. It is possible that the links between shoe characteristics and shoe-owner personality traits would be a bit stronger if we had a sample of shoes posted by individuals –perhaps middle-aged adults– who have fewer financial constraints and perhaps fewer conformity concerns that presumably limit the degree of variability in shoe characteristics within a college student sample.

Individuals perceive the gay non-partisan candidate as significantly more liberal; & conservative individuals reliably prefer in-group gay candidates to straight candidates from the other party

Partisanship, sexuality, and perceptions of candidates. Eric Loepp & Shane M. Redman. Journal of Elections, Public Opinion and Parties, Jan 12 2020.

ABSTRACT: Cultural debates over gay rights have prompted a great deal of scholarship assessing the nature and resiliency of citizen attitudes toward homosexuality in American political life. We posit, however, that more attention should be devoted to LGBT individuals themselves as potential office holders. Specifically, we argue that in an era of increased affective polarization and partisan sorting, party identification of candidates, as well as affectual and ideological attitudes of voters, must be integrated into analyses of the effects of sexuality as a voting heuristic. Drawing on social identity and subtyping theories, we contend that candidate sexuality will influence attitudes about some candidates, but not others. We then present the results of an original survey experiment in which candidate partisanship and sexuality are both manipulated. The data reveal substantial support of our theory: while sexuality is a relevant consideration in the candidate evaluation process, both partisanship of candidates and political attributes of voters can severely condition its effects.

In a world of increasing affective polarization (e.g. Iyengar and Westwood
2015) and partisan-ideological sorting (e.g. Levendusky 2009), studying the
effects of candidate sexuality requires analyzing its interaction with partisanship. We demonstrate that while gay stereotypes remain a potent force in
shaping impressions of political candidates in a non-partisan setting, they
are largely, though not wholly, neutralized in partisan contexts. Voters in
both parties consistently express more support for co-partisans than out-partisans. Even more conservative individuals reliably prefer gay candidates from
their own party to straight candidates from the other. At the same time, candidate sexuality can be an important determinant of voter attitudes when
evaluating gay Republican candidates. These candidates represent a
subtype of Republicans, possessing cognitively inconsistent attributes that
complicate the evaluation process. This tension manifests in the use of sexuality as a conditioning heuristic that generates differential perceptions of gay
and straight Republicans. The results speak to behavioral patterns in the electorate that have important implications for gay candidates that are beginning
to run for office at higher rates than ever. 2018 saw over 600 non-straight candidates run for public office in the United States, including a four-fold increase
over 2010 in the number of candidates nominated for a seat in Congress.16
The 2020 presidential election cycle witnessed the first openly gay candidate
run for his party’s presidential nomination.17 Our results suggest mixed prospects for these candidates. On one hand, sexuality remains a pervasive
influence in non-partisan contexts. Given that political careers often start at
lower levels of public office—which are often non-partisan—the results
imply that if openly gay candidates seek a non-partisan office, their sexuality
status may—if divulged—be used as a cue by voters, such that the candidate
is perceived to be more ideologically liberal. In heavily Democratic areas, this
may be an asset; in more Republican regions, a liability. However, many elections are not non-partisan, and this study contributes important caveats concerning the applicability of sexuality to partisan races. Consistent with recent
research on the effects of partisan affect and sorting (e.g. Mason 2015), we
observe that shared partisanship compels voters to express (dis)approval of
Democratic candidates principally as a function of their party affiliation.
Voters are no more likely to reject a gay Democratic candidate than a straight
one, or vice versa. Popular wisdom, along with some of the extant literature,
suggests that gay individuals face additional barriers that may discourage
them from running for office. While we do not claim gay Democrats will
never face electoral challenges when running for office that their straight
counterparts do not, this research suggests that when it comes to judging
Democratic politicians, the effects of sexuality are diminished. At the same
time, the data suggest a dilemma for gay Republicans that is not dissimilar
to challenges female or non-white Republicans have historically faced:
voters drawing on global stereotypes about partisanship and sexuality must
process conflicting information about them. This could prove advantageous
at times: for instance, a gay Republican candidate may enjoy more support
among Democratic voters than would straight Republican candidates. Yet
Democrats may still perceive gay Republicans to be “too conservative”
when they are contrasted with Democratic candidates from the voters’ own
party. Simultaneously, we show that Republicans may perceive gay Republicans as “not conservative enough,” and express less support for them than
for straight Republican candidates. This challenge is compounded by the
fact that primary elections in the United States mean gay Republicans
would first have to endure the penalties imposed by their sexuality among
party constituents. Even if they were to secure a party nomination, there is
little evidence Democrats would defect from their party to support a gay
Republican in a general election. Patterns of stereotypes and partisan affect
suggest the prospects for openly gay Republican candidates remain bleak.
This research does not purport to be the final authority on the interaction
of sexuality and partisanship. Indeed, multiple caveats are important to
acknowledge. First and foremost, this project represents an initial foray into
this subject; further research building upon the findings uncovered here is
essential. Different treatment designs may yield additional results of interest.
Relatedly, a number of potentially consequential variables that will further
qualify the impact of sexuality in American elections are now ripe for exploration, such as gender, race, and political status (e.g. incumbency). Indeed, just
as women may still be held to different standards than men even if they are
not overtly discriminated against at the polls (e.g. Teele, Kalla, and Rosenbluth
2018), it may also be the case that candidate sexuality matters in particular
electoral contexts more than others. Future work can also extend this analysis
to other phenomena of interest like vote choice in multi-candidate fields.
More expansive conjoint analyses would also be useful to further identify
the causal effects of candidate attributes on voter behavior. Despite these
limitations, we offer an important extension of early research on sexuality
cues that do not integrate partisanship: candidates’ sexuality does not systematically impact how all voters perceive them; instead, its impact is felt when it
does not align with partisanship, when partisan information is altogether unavailable, and among individuals with particularly strong political attitudes.

The developing neonatal cortical folding is unique enough to be considered as a “fingerprint” that can reliably identify an individual within a cohort of infants, even monozygotic twins with similar developmental environments

Individual identification and individual variability analysis based on cortical folding features in developing infant singletons and twins. Dingna Duan et al. Human Brain Mapping, January 12 2020.

Abstract: Studying the early dynamic development of cortical folding with remarkable individual variability is critical for understanding normal early brain development and related neurodevelopmental disorders. This study focuses on the fingerprinting capability and the individual variability of cortical folding during early brain development. Specifically, we aim to explore (a) whether the developing neonatal cortical folding is unique enough to be considered as a “fingerprint” that can reliably identify an individual within a cohort of infants; (b) which cortical regions manifest more individual variability and thus contribute more for infant identification; (c) whether the infant twins can be distinguished by cortical folding. Hence, for the first time, we conduct infant individual identification and individual variability analysis involving twins based on the developing cortical folding features (mean curvature, average convexity, and sulcal depth) in 472 neonates with 1,141 longitudinal MRI scans. Experimental results show that the infant individual identification achieves 100% accuracy when using the neonatal cortical folding features to predict the identities of 1‐ and 2‐year‐olds. Besides, we observe high identification capability in the high‐order association cortices (i.e., prefrontal, lateral temporal, and inferior parietal regions) and two unimodal cortices (i.e., precentral gyrus and lateral occipital cortex), which largely overlap with the regions encoding remarkable individual variability in cortical folding during the first 2 years. For twins study, we show that even for monozygotic twins with identical genes and similar developmental environments, their cortical folding features are unique enough for accurate individual identification; and in some high‐order association cortices, the differences between monozygotic twin pairs are significantly lower than those between dizygotic twins. This study thus provides important insights into individual identification and individual variability based on cortical folding during infancy.


4.1 Infant identification based on cortical folding features

The first main contribution of this study resides in the finding that the cortical folding morphology fingerprints the dynamic developing infant brain and is reliable for individual identification during the first postnatal years. Despite the dramatic global change in cortical size, shape and folding features during birth and 2 years of age (Li, Nie, Wang, Shi, Lin, et al., 2013a; Li, Wang, Shi, Lyall et al., 2014; Lyall et al., 2014; Meng et al., 2014), as also shown in Figure 1, we achieved promising accuracies in identifying 1‐ and 2‐year‐old brains from neonatal cortices using the combinations of cortical folding features (Table 2 ). More importantly, we can thus anticipate that the evidenced fingerprinting power of the neonatal brain of a specific subject can be carried out across the whole lifespan. The reasons for this assumption are in two aspects. First, all major cortical folds and individual variability patterns of the human brain are established at term birth (Duan et al., 2018; Hill et al., 2010; Li, Wang, Shi, Lin, & Shen, 2014a). Second, the most dynamic phase of postnatal brain development is the first 2 years of life, and the folding patterns only undergo minor changes during later childhood and adulthood, thus the 2‐year‐olds' brains largely resemble the adult brains in cortical folding (Gilmore et al., 2007; Li, Nie, Wang, Shi, Lin, et al., 2013a; Li, Nie, Wang, Shi, Gilmore, et al., 2014). Hence, once the 2‐year‐olds can be correctly identified, the possibility of identifying the adult brains based on their neonatal cortical folding patterns would be very high. However, further investigations are required to validate this assumption using a larger longitudinal dataset covering both developing and adult periods.
Table 2 provides us further insights into the infant identification tasks from neonatal cortical folding. Specifically, first, the combination of three kinds of cortical folding features can slightly improve identification accuracies compared to any single feature. Though the improvement is not significant, we prefer to adopt the combinations of three features into the proposed individual identification framework because of two reasons: (a) the mean curvature, average convexity, and sulcal depth provide complementary morphological information of cortical folding from different aspects, as described at the beginning of Section 2.3; (b) the accuracies are all 100% in all tasks, outperforming any single feature and other feature combinations. Second, the identification accuracies in the first two tasks using neonatal brain to identify 1‐ and 2‐year‐olds are lower than that in the third task using 1‐year‐olds to identify 2‐year‐olds. Compared to the first two tasks, the third task is more similar to the adult individual identification, due to the moderate change of cortical folding from Year 1 to Year 2. Thus, these results indirectly validate that the infant individual identification involving neonates is much more challenging than the adult individual identification. Furthermore, the identification accuracies in the first task (i.e., using the dataset with scans at Year 0 to predict the identities of scans at Year 1) are sometimes lower than that of the second task (i.e., using the dataset with scans at Year 0 to predict the identities of scans at Year 2). It might seem less reasonable, since the first task should be easier than the second one, because of the smaller brain development in the first year, in comparison to the first 2 years. To analyze whether this result is caused by the imbalanced datasets in the first two tasks, we repeated experiments with balanced datasets based on both ROI‐based and global‐based methods, as shown in Table S3. Here, to obtain the balanced Year 1 and Year 2 datasets, we randomly selected 200 subjects for 10 times from their original datasets, respectively. Table S3 shows the averaged accuracies of 10 times experiments. As we can see, the accuracies in Task 1 are still lower than Task 2 in some experiments. Excluding the reason of imbalanced datasets, we speculate that the different surface quality in Year 1 and Year 2 datasets might be responsible for this unexpected result in Table 2. Specifically, in the image processing pipeline, the surfaces in Year 0 dataset are reconstructed based on the segmentation results obtained from T2‐weighted images, which show better tissue contrast than the T1‐weighted images of neonatal brains, while the surfaces in Year 1 and Year 2 datasets are reconstructed from T1‐weighted images. Due to the poorer contrast of T1‐weighted images at Year 1 compared with those at Year 2, the surface quality of images in Year 1 dataset in the first task is poorer than that in Year 2 dataset in the second task, which thus might lead to the unexpected slightly lower identification accuracies in the first task.
To handle the case where the subject to be identified has no corresponding scan in the dataset, we set a threshold of the ratio between the frequencies of the first ranked potential identity and the second ranked potential identity. We recorded the ratios during all subjects' identification procedures, and found that the minimum ratios in the first two tasks are 2.0 and 2.2, respectively. The distributions of the ratios are displayed in histograms in Figure 7. Of note, choosing a proper threshold of the ratios is important for the individual identification method. If the threshold is too large, the FPR would be 0, but the FNR would be large; if it is too small, the FPR would be large, and the FNR would be 0. In both situations with improper thresholds, the identification accuracies would be low. The accuracies, FPRs and FNRs based on different thresholds in inverse tasks are displayed in Table S1. Here, we set the threshold to 2.0 according to the above minimum ratio in the first two tasks. Based on thresholding, if a new coming scan has no corresponding scan in the early dataset, we would reject it, thus controlling the false discovery rate.

4.3 Twins study: Individual identification and cortical variability

The third main contribution of our study is the discovery that both the MZ and DZ twins' brains can be correctly identified using the cortical folding features despite similar genetic and environmental influences. Table 5 demonstrates that the cortical folding features are reliable for identifying both infant MZ and DZ twins, and there is no statistical significant difference in the difficulty degree between their identification. Besides, the accuracies show slightly higher values than the corresponding identification accuracies in Table 2, but no significant improvement was found. The slight difference might be caused by the largely imbalanced datasets in the tasks of individual and twin identification. Moreover, Figure 5 and Figures S4‐S5 show that the discordance between MZ twin pairs in most cortical regions, especially the high‐order association cortices, is generally lower than that between DZ twin pairs. Figure 6 further validates that in most of these high‐order association cortices, the degree of discordance between MZ twin pairs is significantly lower than that of between DZ twin pairs, which is in line with the universal biological principles (Kaminsky et al., 2009). In a few regions in Figure 5, the differences between MZ twin pairs are slightly larger than the difference between DZ twin pairs, but no significance was found according to the results of the one‐tailed test. According to the results of these statistical tests, we can have an interesting conclusion that only in some high‐order association cortices, the differences between MZ twin pairs are significantly lower than those between DZ twin pairs, while in other ROIs, there is no statistical significant difference between the discordance of MZ and DZ twins.
It is interesting that the MZ twins, who share the identical genetic makeup (DNA) from a single fertilized egg (Jain, Prabhakar, & Pankanti, 2002; Patwari & Lee, 2008), present distinctive cortical folding patterns in infants. Though the underlying reason is still unclear, recent studies found that the genetically‐identical cells and organisms are not an entirely genetic characteristic, but influenced by both genetic and environmental factors in a dynamic and complex manner (Jha et al., 2018; Raser & O'shea, 2005). Specifically, first, the variation in gene expression may contribute to the phenotypic variability (Patwari & Lee, 2008; Raser & O'shea, 2005) of cortical folding patterns. Second, the prenatal environmental factors (Patwari & Lee, 2008), including the umbilical cord length, access to the nutrition, blood pressure, and position in the womb, also play import roles during the prenatal dynamic development of cortical folding. To this end, we can conclude that (a) both genetic and environmental factors could influence the early development of cortical folding morphology; (b) individual identification based on cortical folding is valid and promising, because there are no two identical brains, even for MZ twins.

4.4 Additional considerations

There are several issues that require further considerations as listed below.

4.4.1 Cortical parcellation choice

From a methodological perspective, the scale and definition of the ROI might influence the patterns of regions with high identification accuracy to some extent. With a cortical region showing high identification accuracy, it might be hard to know which specific part of this region is more critical, given the large sizes of some ROIs from Desikan‐Killiany parcellation (Desikan et al., 2006). Future work may explore the patterns of identification accuracy with a finer‐scale ROI parcellation to better understand which sub‐regions are more or less contributive for individual identification and to better inspect the relation of cortical identification capability and individual variability patterns.

4.4.2 Longitudinal individual cortical folding study across lifespan

It remains unclear to which extent the individual cortical folding is consistent across the whole lifespan. This would be ideally explored using a longitudinal brain dataset with follow‐up MR images from birth to adulthood—which is currently nonexistent. Future studies should include further collecting follow‐up images, and exploring the consistent aspects and developmental aspects of cortical folding during brain development. Additionally, since our experiments with promising identification accuracies were carried out on healthy subjects, it is still unclear that whether specific neurodevelopmental disorder would influence the individual variability and fingerprinting power of the cortical folding. However, it is promising since some studies found that the descriptor of brain morphology can be used to effectively identify adult individuals with Alzheimer's Disease (Peper et al., 2007; Wachinger et al., 2015). Further studies would be required to validate this assumption based on datasets including both healthy subjects and subjects with neurodevelopmental disorders. It would constitute a formidable step forward to demonstrate this in brain development and maturation research.

4.4.3 Infant identification

Though our proposed method based on cortical folding features achieves promising identification accuracies (100%), we do realize that it is not a realistic way for infant identification at present, since MRI is a relatively slow and expensive imaging examination until now. Of note, our main innovation of this study is not the real application of infant identification but rather the three neuroscientific discoveries we reported. Thus, we concisely review the background of current infant identification methods as follows. To our knowledge, this is the first study to leverage the developing cortical folding as the biometric trait for infant identification. There are a few infant identification studies based on other conventional biometric traits, for example, fingerprint (Jain et al., 2016), footprint (E. Liu, 2017), face (Bharadwaj, Bhatt, Singh, Vatsa, & Singh, 2010), or iris (Corby et al., 2006). Compared to the cortical folding features, these biometric traits are more convenient to acquire. However, their performance is less promising, especially when involving neonates (typically < 90% in accuracy) due to the rapidly changing biometric traits during infancy. Besides, these exterior biometric traits are typically unstable and easy to be artificially changed or imitated on purpose in the real application. In future, once brain MRI becomes fast, convenient and cheap to acquire, cortical folding could potentially be a reliable biometric trait for infant identification.

Envy has detrimental ramifications that go beyond the individual & extend to interpersonal relationships: Participants made envious were less helpful & exhibited greater likelihood of engaging in harmful behavior

To Help or To Harm? Assessing the Impact of Envy on Prosocial and Antisocial Behaviors. Anna Maria C. Behler et al. Personality and Social Psychology Bulletin, January 12, 2020.

Abstract: Two studies examined how envy influences prosocial and antisocial behavior. In Experiment 1, participants in an envious state (relative to a neutral state) were less helpful: They picked up fewer dropped pencils in their immediate vicinity. We expanded upon these findings by examining how envy affected both helping and harming behavior in a competitive scenario. In Experiment 2, individuals in envious or neutral states assigned puzzle tasks to another student in a prisoner’s dilemma style scenario. Prosocial and antisocial behaviors were assessed via the difficulty of the assigned puzzles (easy puzzles were considered helpful and difficult puzzles were harmful). We hypothesized that experiencing envy would result in greater motive to harm as well as greater likelihood of engaging in harmful behavior. The hypothesis was supported, suggesting that envy has detrimental ramifications that go beyond the individual and extend to interpersonal relationships.

Keywords: emotion, envy, prosocial, antisocial, helping, aggression

Neural activity may be sufficient for memory but normally requires synapse change; synapse change makes possible and organizes neural activity necessary for memory; molecular encoding is many orders of magnitude more efficient

The search for the engram: Should we look for plastic synapses or information-storing molecules? JesseJames Langille, Charles Randy Gallistel. Neurobiology of Learning and Memory, January 13 2020, 107164.

•    New research calls into question the role of synapse change in memory.
•    Neural activity may be sufficient for memory but normally requires synapse change.
•    Synapse change makes possible and organizes neural activity necessary for memory.
•    Molecular encoding of Shannon information explains memory for quantitative facts.
•    Molecular encoding is many orders of magnitude more efficient.

Abstract: Karl Lashley began the search for the engram nearly seventy years ago. In the time since, much has been learned but divisions remain. In the contemporary neurobiology of learning and memory, two profoundly different conceptions contend: the associative/connectionist (A/C) conception and the computational/representational (C/R) conception. Both theories ground themselves in the belief that the mind is emergent from the properties and processes of a material brain. Where these theories differ is in their description of what the neurobiological substrate of memory is and where it resides in the brain. The A/C theory of memory emphasizes the need to distinguish memory cognition from the memory engram and postulates that memory cognition is an emergent property of patterned neural activity routed through engram circuits. In this model, learning re-organizes synapse association strengths to guide future neural activity. Importantly, the version of the A/C theory advocated for here contends that synaptic change is not symbolic and, despite normally being necessary, is not sufficient for memory cognition. Instead, synaptic change provides the capacity and a blueprint for reinstating symbolic patterns of neural activity. Unlike the A/C theory, which posits that memory emerges at the circuit level, the C/R conception suggests that memory manifests at the level of intracellular molecular structures. In C/R theory, these intracellular structures are information-conveying and have properties compatible with the view that brain computation utilizes a read/write memory, functionally similar to that in a computer. New research has energized both sides and highlighted the need for new discussion. Both theories, the key questions each theory has yet to resolve and several potential paths forward are presented here.

Check also Abraham WC, Jones OD, Glanzman DL. Is plasticity of synapses the mechanism of long-term memory storage?. NPJ Sci Learn. 2019;4:9. Jul 2 2019. doi:10.1038/s41539-019-0048-y
Abstract: It has been 70 years since Donald Hebb published his formalized theory of synaptic adaptation during learning. Hebb’s seminal work foreshadowed some of the great neuroscientific discoveries of the following decades, including the discovery of long-term potentiation and other lasting forms of synaptic plasticity, and more recently the residence of memories in synaptically connected neuronal assemblies. Our understanding of the processes underlying learning and memory has been dominated by the view that synapses are the principal site of information storage in the brain. This view has received substantial support from research in several model systems, with the vast majority of studies on the topic corroborating a role for synapses in memory storage. Yet, despite the neuroscience community’s best efforts, we are still without conclusive proof that memories reside at synapses. Furthermore, an increasing number of non-synaptic mechanisms have emerged that are also capable of acting as memory substrates. In this review, we address the key findings from the synaptic plasticity literature that make these phenomena such attractive memory mechanisms. We then turn our attention to evidence that questions the reliance of memory exclusively on changes at the synapse and attempt to integrate these opposing views.