The golden ratio as an ecological affordance leading to aesthetic attractiveness

The golden ratio as an ecological affordance leading to aesthetic attractiveness. Daniela De Bartolo,Maria De Luca,Gabriella Antonucci,Stefan Schuster,Giovanni Morone,Stefano Paolucci,Marco Iosa. PsyCh Journal, December 23 2021. https://doi.org/10.1002/pchj.505

Abstract: The golden ratio (GR) is an irrational number (close to 1.618) that repeatedly occurs in nature as well as in masterpieces of art. The GR has been considered a proportion perfectly representing beauty since ancient times, and it was investigated in several scientific fields, but with conflicting results. This study aims at investigating if this proportion is associated with a judgment of beauty independently of the type of the stimulus, and the factors that may affect this aesthetic preference. In Experiment 1, an online psychophysical questionnaire was administered to 256 volunteers asked to choose among three possible proportions between the parts of the same stimulus (GR, 1.5, and 1.8). In Experiment 2, we recorded eye movements in 15 participants who had to express an aesthetic judgment on the same stimuli of Experiment 1. The results revealed a slight overall preference for GR (53%, p < .001), with higher preferences for stimuli representing humans, anthropomorphic sculptures, and paintings, regardless of the cultural level. In Experiment 2, a shorter dwell time was significantly associated with a better aesthetic judgment (p = .005), suggesting the possibility that GR could be associated with easier visual processing, and it could be hence considered as a visual affordance.

DISCUSSION

The main purpose of this study was to establish whether the presence of the GR may favor the perception of beauty in aesthetic judgments and which factors might influence it, clarifying the main controversies found in previous studies (Benjafield & Adams-Webber, 1976; Berlyne, 1970; Boselie, 1984; Davis & Jahnke, 1991; Di Dio et al., 2007; Fechner, 1865; Green, 1995; Witmer, 1893; Zeising, 1855).

First of all, we found a slight but significant preference for GR, but its entity depended on the category of the stimulus. This preference was statistically significant for human photographs, in both the experiments, and for sculptures and paintings in Experiment 1 (being only close to a significant threshold for virtual humanoid figures).

Conversely, we did not find a significant preference for GR in geometric stimuli. These findings are in line with some previous results (Di Dio et al., 2007; Di Dio et al., 2011) but in contrast with other studies finding a preference for GR also for geometric figures (Fechner, 1865; Russell, 2000). There are many possible explanations for the high variability among studies related to the possible preference for golden rectangles. First of all, it could be related to different methodologies related to how central tendency was computed: by means of mean, median, or modal values, with the GR that could emerge as mean value even if it was not the most frequent choice, as also previously suggested (Green, 1995). Indeed, in contrast to previous research on lines and geometric shapes' aesthetic preference, recent studies used more ecological experimental paradigms including natural and anthropomorphic figures, highlighting that geometric simple stimuli could be poorly attractive for our culture (Di Dio et al., 2007; Di Dio et al., 2011). Furthermore, with respect to the study of Fechner (1865) and successive ones, subjects are now more often exposed to rectangular shapes different from GR, such as those of television screens, monitors, or smartphones having proportions closer to 1.8 (16:9 = 1.78, or 1980:1020 pixels = 1.78), or also paper sheets closer to 1.5 (A4: 1.41).

The GR is often present in many natural stimuli (Iosa et al., 2018). Indeed, subjects might prefer stimuli recognized as original, as in our study occurred for human photographs, with GR preferred for stimuli originally in GR (oGR vs. noGR), despite participants not knowing which was the original stimuli.

The golden section was conceivably identified by anatomical Greek investigations in the 5th century BCE (as in the canon of Protagoras) with the idea to reproduce the harmony of the human body in the anthropomorphic sculptures and then in other artworks (Haines & Davies, 1904; Iosa et al., 2018). It should be considered that anthropomorphic stimuli have their own symmetry given by the right–left relationship along the horizontal axis, whereas the golden section defines the vertical harmony of a standing human being. Hence, the GR preference could occur more frequently on the vertical than horizontal axis. Despite our studies not investigating this aspect, it should be noted that the rectangles of Fechner (1890) had the longer segment along the vertical axis, whereas in our and other studies (McManus, 1980; Russell, 2000) the longer dimension of rectangles and that of the bisected line was the horizontal one.

Despite this, Renaissance artists provided a horizontal division of their paintings according to the golden section, such as in The Flagellation of Christ and The Creation of Adam (de Campos et al., 2015), with these stimuli that can be mentally divided into two parts and visually explored horizontally. A slight preference for GR was found in our paintings (54.6%), quite independent if the original stimuli was or not in golden proportion. Wölfflin (1994) questioned the preference for GR when observing an abstract rectangle because it should be related to a mental comparison of the lengths of basis, height, and their sum, again claiming that GR may “present an average measure conforming to man”.

This hypothesis put in relationship the GR with “objective beauty”, because it was related to a harmonic property intrinsic to the stimuli, but there is also an alternative hypothesis, reported in the so-called constructal theory, referring to “perceptual beauty” suggesting that the preference for GR was related to the hypothesis that visual system scans the world approximatively in golden proportion (Bejan, 2009). Di Dio et al. (2007) identified also the “subjective beauty” driven by one's own emotional experiences and related to the activation of the amygdala, whereas the objective beauty related to the intrinsic properties of the stimulus is based on a joint activation of sets of cortical neurons of lateral occipital cortex, parietal cortex, and anterior insula. All these processes could be not mutually exclusive and cohabit, forming our sense of beauty.

This integrated approach works even better considering GR as an affordance, and hence a property intrinsic to the stimulus that is recognized by our visual system and favoring the visual process. In fact, Gibson proposed the theory of affordances, suggesting that subjects noted the features of a stimulus that may constitute functional relations between the stimulus and the perceiver (Gibson, 2014; Lobo et al., 2018). The abstraction of geometric figures and even of virtual humanoids might hence have mitigated this preference, in accordance with the ecological approach suggested by Gibson for the visual system (Gibson, 2014). The cultural level of subjects did not seem to influence the general preference for GR. This result could be read in conjunction with previous findings that the aesthetic judgment of beauty was mainly independent by sociocultural factors, intelligence, personality, and age (Eysenck & Tunstall, 1968). However, in our study, culture was assessed in terms of scholarly level, but different cultures were not analyzed, and further studies could investigate the preferences for GR comparing subjects of Western versus Eastern Countries.

When we analyzed single categories of stimuli, the preference for GR in human photographs and sculptures was related to art knowledge. These two types of stimuli have in common the same criterion for GR: the ratio between the distance of the navel from the ground and that between the navel and the top of the head. Virtual humanoids had the same proportion, but the judgments about them seemed to be not affected by cultural level. Probably, this judgment mainly depended on the realism of their faces, as shown by the long time spent by observers looking at the virtual faces in Experiment 2. Furthermore, being human bodies on average in GR, humans might have reflected this proportion in the concept of beauty, and it led to the adoption of this parameter also in some classical artistic masterpieces, starting from anthropomorphic sculptures (Hernández-Castro, 2007).

Human beings may associate, more or less consciously, the concept of beauty to their own body proportions (Burrell, 1932), as is the case with the preference of symmetric figures that could be related to the symmetry of the human body (Evans et al., 2012; Huang et al., 2018; Mühlenbeck et al., 2016). As well as symmetry being considered as an affordance in accordance with the ecological approach suggested by Gibson for vision (2014), the GR that can be considered as a symmetry of higher order (Liu & Sumpter, 2018) could also be another visual natural affordance, preferred by humans and put in artworks by artists.

In our study, the proposed paintings have the longest dimension horizontal; indeed, the golden ideal division was along the horizontal axis. A slight preference (54.6%) was found for GR, quite independently if the stimulus was or not originally in GR. With respect to the geometric figures, participants could perceive the harmony of a scene ideally divided in two parts according to the GR, even if this scene is represented with the horizontal length longer than the vertical. Considering that for symmetry there is a perceptual sensitivity to the orientation of the stimulus (1905; Fisher & Bornstein, 1982; Mach, 1883), and that there are no studies that directly investigated the relationship between GR and the orientation of the stimulus, future studies should investigate whether there is a dependence on the orientation with which it is presented the stimuli and the possible preference for GR.

Despite our study lacking this direct comparison, the bimodal distribution of dwell time found in Experiment 2 for human figures for which the golden section regards the vertical axis, are similarly replicated for the paintings in which it regards the horizontal axis. In general, the results of Experiment 2 were found in accordance with those of Experiment 1 and seem to confirm the hypothesis of GR as an affordance. In Experiment 2, we found no significant differences between the three proportions related to the total exploration time, but also some significant differences with respect to specific areas of interest. Further, analyzing the dwell times, significant differences among GR, R1.5, and R1.8 were found regarding the exploration of the AOIm, that is, the specific AOI where the image modification was performed. A significant negative correlation was found between the AOIm dwell time and the aesthetic judgment only for GR stimuli. This could indicate that the subject does not need to observe that area for too long to judge it as beautiful if it is in golden proportion.

Despite previous studies showing that the aesthetic appreciation of beauty is not based on an “immediate” response and may even require more time to discriminate the main characteristics of the stimuli (Bar et al., 2006; Evans et al., 2012; Huang et al., 2018; Liu & Sumpter, 2018; Mühlenbeck et al., 2016), the presence of GR may have reduced this time because it was quickly recognized and preferred by the observers. So, hypothesizing GR as an affordance, it may be implicitly recognized, facilitating the processing of visual information relating to a stimulus, making aesthetic experience more fluent, in accordance with the “processing fluency theory” for which that fluency could contribute to the pleasantness of the experience associated with the perception of beauty (Witmer, 1893).

It is noteworthy that the GR divides the human stature in a region roughly close to the body center of mass and could even play an important role in human motor behavior (Iosa et al., 2018). It should be noted that the exposition to GR does not regard only the visual system: GR was recently found as a harmonic feature of voluntary and involuntary rhythmic human movements, such as cardiac (Yetkin et al., 2013), respiratory (Iared et al., 2016), and walking rhythms (Iosa et al., 2013; Iosa et al., 2016; Iosa et al., 2019; Serrao et al., 2017). In fact, walking performed with GR between gait phases allows humans to harmonize locomotor acts (Iosa et al., 2016; Iosa et al., 2019), thus reducing energy expenditure (Serrao et al., 2017). Furthermore, it has been demonstrated that perception of internal gait rhythm may be modulated (De Bartolo, Belluscio, et al., 2020a) and that the harmonic structure of music can ameliorate harmony of walking in patients with Parkinson's disease (De Bartolo, Morone, et al., 2020b), especially if acoustic stimulation presents GR harmony (Belluscio et al., 2021), confirming the possibility to consider GR as an affordance to exploit by the observer/listener/acting subject.

However, we must bracket this proposal with some caveats. The main limitation of Experiment 1 was the online administration of the questionnaire that did not allow for controlling some variables such as the eyes' positions with respect to the screen, the response time of the subjects, or their attention level. For example, the questionnaire was formed by 51 items, and it might have led to a progressive physiological decline in the participants' attention due to fatigue.

However, the online administration allowed for enrolling a wide sample of subjects (N = 256) that could have attenuated the above-mentioned limits. Experiment 2 was performed in more controlled conditions, and its results confirmed those obtained in Experiment 1. Subjects were required to judge the most liked stimulus, without any investigations related to the judgment of naturalness, so caution is needed in discussing the role of naturalness of stimuli and its relationship to the preference for stimuli originally or not in GR.

Finally, in our study we did not manipulate canonical orientation of stimuli, so we included only vertical stimuli for anthropomorphic figures and horizontal for images of artworks. Further studies should investigate the possible differences in the GR preferences for vertical versus horizontal stimuli, and these results could contribute to understand the relationship between GR and visual scan process.

An Eye-Tracking Investigation on Mirror Gazing: Those of higher self-esteem spent less time checking themselves in a mirror

Effects of Self-Esteem on Self-Viewing: An Eye-Tracking Investigation on Mirror Gazing. Jonas Potthoff, Anne Schienle. Behav. Sci. 2021, 11(12), 164. Nov 29 2021. https://doi.org/10.3390/bs11120164

Abstract: While some people enjoy looking at their faces in the mirror, others experience emotional distress. Despite these individual differences concerning self-viewing in the mirror, systematic investigations on this topic have not been conducted so far. The present eye-tracking study examined whether personality traits (self-esteem, narcissism propensity, self-disgust) are associated with gaze behavior (gaze duration, fixation count) during free mirror viewing of one’s face. Sixty-eight adults (mean age = 23.5 years; 39 females, 29 males) viewed their faces in the mirror and watched a video of an unknown person matched for gender and age (control condition) for 90 s each. The computed regression analysis showed that higher self-esteem was associated with a shorter gaze duration for both self-face and other-face. This effect may reflect a less critical evaluation of the faces.

Keywords: face; self-perception; mirror; eye-tracking; self-esteem; self-disgust; narcissism

4. Discussion

This study investigated whether gaze parameters while viewing one’s face in the mirror are associated with the personality traits of self-esteem, self-disgust, and narcissism propensity. High self-esteem indicates that, on the whole, individuals are satisfied with themselves and are not overly critical [30,31]. In previous eye-tracking research, elevated self-esteem was associated with attentional biases towards self-faces [13]. Surprisingly, in the present investigation, higher self-esteem was associated with shorter—possibly less critical—viewing of the own face. It is possible that people with high self-esteem need less time to evaluate themselves (critically), while low self-esteem seems to be associated with a more thorough and more prolonged evaluation of one’s facial appearance.

Following this interpretation, the shorter viewing time of the other face associated with higher self-esteem would imply that individuals with high self-esteem are also less critical of others [32]. It is possible that in previous research [13] this viewing pattern could not be identified due to brief exposure times. The participants looked at the faces until they identified them. This took them less than one second on average. Additionally, in previous research, faces were not viewed freely, and task demands (face identification) may have overruled a critical and thorough evaluation of the faces [13]. Future research needs to investigate the effect of exposure time and viewing tasks on gaze behavior concerning self-face and other-face.

Self-esteem did neither predict the number of fixations on self-face nor other-face. Many short fixations (i.e., hyperscanning) are commonly conducted when affective stimuli with negative valence and high intensity are explored [22,33]. In the present study, dynamic faces with neutral expressions were viewed, which do not induce high arousal, at least in non-clinical samples [19,20,21]. While self-esteem predicted a more thorough evaluation of faces (longer viewing time), it was not associated with visual hyperscanning, which would have required elevated arousal. Taken together, the results suggest that low self-esteem is related to a thorough but calm evaluation of faces.

Earlier investigations indicated that the number of fixations on specific face areas differs between self-face and other-face viewing. Hoffmann et al. [8] observed that more fixations were conducted on the eyes when viewing unfamiliar faces than the own face. We refrained from using a similar analysis approach (an analysis of fixation counts for specific facial areas) because of insufficient spatial precision of the measuring procedure. There are slight interindividual differences in the position of facial features (e.g., location of eyes, mouth), which cannot be detected with sufficient spatial accuracy during mirror viewing. It would have been possible to control for the location of the eyes during mirror viewing by adjusting the chinrest for each participant until they see their eyes at a predefined mirror location. This procedure would, however, lead to self-face exposure before the eye-tracking experiment begins. Therefore, we focused on the gaze behavior for the face as a whole.

There was no relationship between NPI scores and gaze behavior. Narcissism propensity was neither associated with a more thorough (prolonged) viewing nor hyperscanning. These null-findings contrast our expectations and previous research, especially for self-face viewing [15]. In the present paradigm, participants viewed self-faces and other faces one after another and not simultaneously (e.g., as image pairs). It is possible that associations between narcissism propensity and viewing behavior did not show up because participants could not directly compare their faces with the faces of others. Furthermore, participants did not perform any task in which they could have compared their performance with the performance of others. Future studies should investigate whether narcissism propensity is associated with specific self-face viewing behaviors in competitive contexts (i.e., when comparing one’s own and others’ physical appearance).

The NPI assesses feelings of self-importance. However, narcissism has different facets. It has been suggested to distinguish between grandiose and vulnerable narcissism [34,35]. Vulnerable narcissistic individuals are anxious, defensive, and avoidant, while grandiose narcists are extraverted and self-satisfied [36]. Additionally, there are intrapersonal and interpersonal aspects of narcissism [37]. To maintain a grandiose self, people with a high narcissism propensity might, on the one hand, strive for feelings of uniqueness (intrapersonal) [38]. On the other hand, they can also devaluate others or strive for supremacy (interpersonal) [39]. Therefore, more differentiated NP measures should be used in the future, which can differentiate between these separable yet related expressions of narcissism that should prompt different styles of self-viewing [40].

Self-disgust also showed no association with viewing the own face. Self-disgust has been conceptualized as a dysfunctional personality trait [12,41] which typically has a very low level in mentally healthy individuals [41]. This was also the case in the present investigation. In contrast, Ypsilanti, Robson et al. [6] analyzed eye-tracking data from participants with mental health problems. This group with elevated self-disgust displayed avoidance of self-viewing. Therefore, the present null results do not contrast previous findings [5,6]. Future research should further investigate self-face viewing in conditions with elevated self-disgust, such as depression [2,42], disordered eating [43,44,45], and body dissatisfaction [45,46,47]. For example, body dysmorphic disorder (BDD) is associated with high self-disgust [47] but not with avoidance of self-viewing. Many patients with BDD even report spending a significant amount of time checking themselves in the mirror [45]. Mirror viewing paradigms can therefore contribute to a deeper understanding of self-viewing avoidance as well as excessive mirror viewing in eating disorders and BDD. For these disorders, mirror exposure is a commonly used therapy component [48].

We also investigated possible gender effects on face-viewing behavior. In general, males, as well as females, spent the majority of the 90 s-viewing time on the faces. Thus, there was no indication of face avoidance. Male participants were characterized by a longer total viewing time. They showed a longer gaze duration for both the own face and the other face. Previous studies have already demonstrated that face exploration dynamics (for other faces) differentiate men and women [49,50]. In an investigation by Coutrot et al. [49], the participants (203 males and 202 females) watched videos of actors. Male participants showed longer fixation durations for the faces than female participants. However, this difference was small. Overall, face viewing has many functions and serves multiple purposes (e.g., aiding speech perception [51], emotion recognition [52], person identification [53], or affective evaluation [15]). Moreover, context factors (e.g., cultural, social) have to be considered as well [54]. It needs further investigation whether differences in face-viewing intentions might have contributed to the observed gender difference in gaze duration.

It is plausible that several limitations might have influenced the results obtained. We studied a convenience sample, and the participants were healthy, predominantly young students. Therefore, the present results cannot be generalized to other samples. Furthermore, the study did not differentiate between different aspects of narcissism propensity.

We preferably copy the behavior of our own group’s members, even if group the group is arbitrary and novel, and even if one's peers are less competent than others

Copy the In-group: Group Membership Trumps Perceived Reliability, Warmth, and Competence in a Social-Learning Task. Marcel Montrey, Thomas R. Shultz. Psychological Science, December 23, 2021. https://doi.org/10.1177/09567976211032224

Abstract: Surprisingly little is known about how social groups influence social learning. Although several studies have shown that people prefer to copy in-group members, these studies have failed to resolve whether group membership genuinely affects who is copied or whether group membership merely correlates with other known factors, such as similarity and familiarity. Using the minimal-group paradigm, we disentangled these effects in an online social-learning game. In a sample of 540 adults, we found a robust in-group-copying bias that (a) was bolstered by a preference for observing in-group members; (b) overrode perceived reliability, warmth, and competence; (c) grew stronger when social information was scarce; and (d) even caused cultural divergence between intermixed groups. These results suggest that people genuinely employ a copy-the-in-group social-learning strategy, which could help explain how inefficient behaviors spread through social learning and how humans maintain the cultural diversity needed for cumulative cultural evolution.

Keywords: cumulative cultural evolution, intergroup dynamics, social-learning strategies, transmission biases, open data, preregistered

Discussion

Although previous studies have found an apparent in-group bias in social learning, they have failed to resolve whether this constitutes a genuine social-learning strategy or a mere confluence of other factors (Buttelmann et al., 2013; Howard et al., 2015). Our study disentangled group membership from similarity and familiarity by assigning group membership at random. We found that rather than eliminating the preference for in-group members, this approach resulted in a robust in-group-copying bias, which (a) was bolstered by a tendency to observe in-group members, (b) overrode participants’ stated beliefs, (c) grew stronger when social information was scarce, and (d) even caused cultural divergence between intermixed groups. Taken together, our findings suggest that people genuinely employ a copy-the-in-group strategy and that group membership has both a direct and indirect effect on copying.

Why might a copy-the-in-group strategy have evolved in the first place? One reason could be that it allowed humans to rapidly adopt and vigorously maintain group norms that enhance coordination (McElreath et al., 2003) or promote cooperation (Boyd & Richerson, 2009). Another reason could be that social learning is useful only to the extent that adopting other people’s behavior yields similar payoffs (Laland, 2004). For example, copying out-group members could be less efficient or even counterproductive if groups differ in terms of what behavior is punished or rewarded. Finally, such a strategy could also have evolved because it minimized the risk of deception. Because social learning is essentially information scrounging (Kameda & Nakanishi, 2002), in which the copier benefits from other people’s knowledge without incurring the same costs, knowledgeable individuals have an incentive to mislead others. However, this incentive is minimized when observed individuals have a vested interest in the copier’s success. This holds true in kin relationships (Laland, 2004) and likely generalizes to other settings, such as intergroup competition.

Although the in-group-copying bias may be adaptive, we were careful to control for factors that could justify such a bias or evoke a similar-looking one. First, we limited the role of similarity and familiarity by assigning participants to groups at random. Second, we ensured that there was no inherent advantage to copying either group by giving participants access to the same information and by discouraging deception. Third, we deterred intergroup competition by framing the game in terms of individual performance and by obscuring group membership whenever participants saw others’ scores. Fourth, we prevented selective copying from advancing social goals (Over & Carpenter, 2012), such as inclusion (Watson-Jones et al., 2016), by limiting social interactions to unidirectional observations of previous participants. Finally, we matched everyone with an equal number of participants from each group to ensure that fellow in-group members did not form a majority. That being said, because cultures could conceivably vary in their reliance on group membership, the generalizability of our findings may be limited by our sample consisting solely of U.S. residents. Furthermore, although online recruitment platforms often yield a more diverse pool of participants than traditional student samples, they raise other concerns about data quality. For a brief overview of these concerns and our analysis of their impact, see “Data Quality” in Supplemental Information About Data Quality, Preregistration, and Other Results.

In addition to controlling for potential confounds, we also tested several proposed explanations for why people may preferentially copy in-group members. One is that we attend to them more often (Kinzler et al., 2011). This seems sensible, given that native-language speakers attract more attention from a very young age (Kinzler et al., 2007) and that adults bias their attention toward in-group members, whether that group is preexisting or novel (Kawakami et al., 2014). However, developmental studies have failed to reveal any obvious in-group attentional bias in social learning (Oláh et al., 2016), and both looking times (Buttelmann et al., 2013; Pető et al., 2018) and eye-tracking data (Howard et al., 2015) contradict this hypothesis. It is therefore curious that most participants in our experiments (70% and 67%) observed the in-group more often and that this drove much of the in-group bias in copying. One possibility is that humans become more likely to attend to in-group members over the course of development. For example, instead of attention guiding children’s copying, biases in copying could shape their attention. Another possibility is that attention played a greater role in our study because participants explicitly chose whom to observe and paid a clear opportunity cost for each selection. Our findings may thus be particularly relevant to contexts in which people have strong and explicit control over their sources of social information, such as on social media.

Another proposed explanation for why people may prefer to copy in-group members is that we ascribe greater competence to the in-group (Kinzler et al., 2011) or view out-group members as less reliable (Oláh et al., 2016). This hypothesis is rooted in the classic social-psychology finding that in-group members are evaluated more favorably, even when groups are arbitrary and novel (Brewer, 1979). Indeed, we found that the in-group enjoyed advantages in perceived reliability, warmth, and competence. However, none of these beliefs had much effect on whom participants copied. On the contrary, because the in-group-copying bias arose even among participants who viewed the out-group as more competent, our results seemingly contradict the axiom that social-learning strategies exist solely to help people identify and adopt the most effective behavior (Kendal et al., 2018).

In fact, if people are predisposed to copy in-group members, perhaps even when their perceived competence is low, this could help explain the spread of inefficient or even deleterious behaviors. For example, opposition to vaccination is often disseminated through highly clustered and enclosed online communities (Yuan & Crooks, 2018) who use in-group-focused language (Mitra et al., 2016). Likewise, fake news tends to spread among politically aligned individuals (Grinberg et al., 2019), and the most effective puppet accounts prefer to portray themselves as in-group members rather than as knowledgeable experts (Xia et al., 2019). Our research also sheds light on why social media platforms seem especially prone to spreading misinformation. By offering such fine-grained control over whom users observe, these platforms may spur the creation of homogeneous social networks, in which individuals are more inclined to copy others because they belong to the same social group.

Finally, the fact that the in-group-copying bias produced some amount of cultural divergence in both of our experiments is of particular interest from a cultural evolutionary point of view. This is because the exceptional complexity of human culture and technology (Montrey & Shultz, 2020) likely depends on integrating and recombining diverse cultural traits (Mesoudi & Thornton, 2018). Theory suggests that for cultural evolution to be cumulative (i.e., for complexity to increase over time), populations may have to be fragmented to some degree so that unique traits have the opportunity to flourish (Derex et al., 2018). Otherwise, cultural traits may homogenize, leaving learners with little to recombine. Although the intergroup differences in behavior we observed do not rise to the level of cultural traditions, our findings could help explain how cultural differences persist in intermixed groups (McElreath, 2004). A copy-the-in-group strategy could thus be one mechanism for achieving the cultural diversity needed for cumulative cultural evolution.

Watching A Lecture Twice At Double Speed Can Benefit Learning Better Than Watching It Once At Normal Speed

Learning in double time: The effect of lecture video speed on immediate and delayed comprehension. Dillon H. Murphy,Kara M. Hoover,Karina Agadzhanyan,Jesse C. Kuehn,Alan D. Castel. Applied Cognitive Psychology, November 14 2021. https://doi.org/10.1002/acp.3899

Abstract: We presented participants with lecture videos at different speeds and tested immediate and delayed (1 week) comprehension. Results revealed minimal costs incurred by increasing video speed from 1x to 1.5x, or 2x speed, but performance declined beyond 2x speed. We also compared learning outcomes after watching videos once at 1x or twice at 2x speed. There was not an advantage to watching twice at 2x speed but if participants watched the video again at 2x speed immediately before the test, compared with watching once at 1x a week before the test, comprehension improved. Thus, increasing the speed of videos (up to 2x) may be an efficient strategy, especially if students use the time saved for additional studying or rewatching the videos, but learners should do this additional studying shortly before an exam. However, these trends may differ for videos with different speech rates, complexity or difficulty, and audiovisual overlap.

Popular version: Watching A Lecture Twice At Double Speed Can Benefit Learning Better Than Watching It Once At Normal Speed. Emma Young. https://digest.bps.org.uk/2021/12/21/watching-a-lecture-twice-at-double-speed-can-benefit-learning-better-than-watching-it-once-at-normal-speed/

1.5 million years of hunting: Larger species were hunted to extinction or until they became exceedingly rare

Levantine overkill: 1.5 million years of hunting down the body size distribution. Jacob Dembitzer, Ran Barkai, Miki Ben-Dor, Shai Meiri. Quaternary Science Reviews, Volume 276, January 15 2022, 107316. https://doi.org/10.1016/j.quascirev.2021.107316

Abstract: Multiple large-bodied species went extinct during the Pleistocene. Changing climates and/or human hunting are the main hypotheses used to explain these extinctions. We studied the causes of Pleistocene extinctions in the Southern Levant, and their subsequent effect on local hominin food spectra, by examining faunal remains in archaeological sites across the last 1.5 million years. We examined whether climate and climate changes, and/or human cultures, are associated with these declines. We recorded animal abundances published in the literature from 133 stratigraphic layers, across 58 Pleistocene and Early Holocene archaeological sites, in the Southern Levant. We used linear regressions and mixed models to assess the weighted mean mass of faunal assemblages through time and whether it was associated with temperature, paleorainfall, or paleoenvironment (C3 vs. C4 vegetation). We found that weighted mean body mass declined log-linearly through time. Mean hunted animal masses 10,500 years ago, were only 1.7% of those 1.5 million years ago. Neither body size at any period, nor size change from one layer to the next, were related to global temperature or to temperature changes. Throughout the Pleistocene, new human lineages hunted significantly smaller prey than the preceding ones. This suggests that humans extirpated megafauna throughout the Pleistocene, and when the largest species were depleted the next-largest were targeted. Technological advancements likely enabled subsequent human lineages to effectively hunt smaller prey replacing larger species that were hunted to extinction or until they became exceedingly rare.

Keywords: LevantMegafaunaEarly humansHuntingPleistoceneQuaternaryClimate

How a Tardigrade "Micro Animal" Became Quantum Entangled with Superconducting Qubits

Entanglement between superconducting qubits and a tardigrade. K. S. Lee, Y. P. Tan, L. H. Nguyen, R. P. Budoyo, K. H. Park, C. Hufnagel, Y. S. Yap, N. Møbjerg, V. Vedral, T. Paterek, R. Dumke. arXiv Dec 16 2021. https://arxiv.org/abs/2112.07978

Quantum and biological systems are seldom discussed together as they seemingly demand opposing conditions. Life is complex, "hot and wet" whereas quantum objects are small, cold and well controlled. Here, we overcome this barrier with a tardigrade -- a microscopic multicellular organism known to tolerate extreme physiochemical conditions via a latent state of life known as cryptobiosis. We observe coupling between the animal in cryptobiosis and a superconducting quantum bit and prepare a highly entangled state between this combined system and another qubit. The tardigrade itself is shown to be entangled with the remaining subsystems. The animal is then observed to return to its active form after 420 hours at sub 10 mK temperatures and pressure of 6×10−6 mbar, setting a new record for the conditions that a complex form of life can survive.

Popular version: How a Tardigrade "Micro Animal" Became Quantum Entangled with Superconducting Qubit. Dec 22 2021. https://www.discovermagazine.com/the-sciences/how-a-tardigrade-micro-animal-became-quantum-entangled-with-superconducting

Within each colony of some ants, only some individuals are capable of performing a complex sequence of behavioral patterns to free trapped nestmates, sequence that is responsive to the particular circumstances of that entrapment & how the rescue operation unfolds

Rescue specialists in Cataglyphis piliscapa ants: The nature and development of ant first responders. Elise Nowbahari, Karen L. Hollis, Melanie Bey, Lara Demora & Jean-Luc Durand. Learning & Behavior, Dec 16 2021. https://link.springer.com/article/10.3758/s13420-021-00503-3

Abstract: Previous research in our laboratories has demonstrated that, within each colony of Cataglyphis piliscapa (formerly C. cursor) ants, only some individuals are capable of performing a complex sequence of behavioral patterns to free trapped nestmates—a sequence that not only is memory-dependent but also is responsive to the particular circumstances of that entrapment and how the rescue operation unfolds. Additionally, this rescue behavior is inherited patrilineally from but a few of the many males that fertilize the eggs of the colony’s single queen. Here, we describe three experiments to explore rescue behavior further—namely, whether rescuers are in any way selective about which nestmates they help, how the age of rescuers and the victims that they help affect the quantity and quality of the rescue operation, and when this complex behavior first emerges in an ant’s development. Taken together with the previous heritability analysis, these behavioral experiments provide clear evidence that the ability to rescue nestmates in distress should be recognized as a specialization, which together with other specialized tasks in C. piliscapa, contributes to a division of labor that increases the efficiency of the colony as a whole and, thus increases its reproductive success.

Geographic Variation in Personality is Associated With Fertility Across the United States

Geographic Variation in Personality is Associated With Fertility Across the United States. Eleanor J. Junkins et al. Personality Science, 2021, Vol. 2, Article e7275, Dec 16 2021. https://doi.org/10.5964/ps.7275

Abstract: Levels of fertility and the shape of the age-specific fertility schedule vary substantially across U.S. regions with some states having peak fertility relatively early and others relatively late. Structural institutions or economic factors partly explain these heterogeneous patterns, but regional differences in personality might also contribute to regional differences in fertility. Here, we evaluated whether variation in extraversion, agreeableness, conscientiousness, neuroticism, and openness to experience measured at the U.S. state-level was associated with the level, timing, and context of fertility across states above and beyond sociodemographics, voting behavior, and religiosity. Generally, states with higher levels of agreeableness and conscientiousness had more traditional fertility patterns, and states with higher levels of neuroticism and openness had more nontraditional fertility patterns, even after controlling for established correlates of fertility (r ~ |.50|). Personality is an overlooked correlate that can be leveraged to understand the existence and persistence of fertility differentials.

Keywords: personality, fertility, demography, geographic variation, Big Five

Non-Technical Summary

What is the study’s background?

People living in different regions of the U.S. make different choices about having children. In some regions, people have babies early and often, whereas in other regions, people have babies late or not at all.

Why was this study done?

This study was done to test whether regional differences in personality were related to regional differences in fertility. Researchers in the field of demography, which studies how populations differ in birth and death rates, have typically not considered that people living in different regions may have different personalities—meaning different patterns of thoughts, feelings, and behaviors that are stable across time and context.

What did the researchers do and find?

Researchers in this study used data on how each U.S. state differs in its average level of five basic personality traits, known as the “Big Five”. Residents of states like Wisconsin are higher on agreeableness (warmth and consideration of other people) and conscientiousness (dutifulness and planning ahead), and they show more traditional patterns of fertility. The regional differences in personality were predictive of fertility patterns even after considering differences in religiousness and politics.

What do these findings mean?

People’s fertility behaviors are related to where they live. Part of what makes areas of the U.S. different from one another is the personality traits of the people who live there. These results have the potential to expand theoretical models of population growth and change by linking demography with personality science.

The woman in high heels was perceived as being more sexually attractive, physically attractive, feminine, & of a higher status; were not rated as more or less warm, enthusiastic, trustworthy, socially competent, healthy, intelligent, affectionate, friendly, or successful

On a pedestal: High heels and the perceived attractiveness and evolutionary fitness of women. T. Joel Wade et al. Personality and Individual Differences, Volume 188, April 2022, 111456. https://doi.org/10.1016/j.paid.2021.111456

Abstract: We analyzed the responses of 448 participants who completed questions on attractiveness and other evolutionary fitness related traits, and long- and short-term mating potential, of a woman in either high heeled or flat shoes. We hypothesized that the woman in high heels would be rated as more attractive and evolutionarily fit by both men and women, and preferred for short-term mating by men. The hypothesis was partially supported. The woman in high heels was perceived as being more sexually attractive, physically attractive, feminine, and of a higher status. Additionally, women rated women as having a higher status regardless of the shoe, than men, while men rated women as having higher short- and long-term mating potential, than women did, regardless of the shoe. We discuss the implications of these findings.

Keywords: High heelsAttractivenessSilhouetteShoesFeminineStatus

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positive effect maybe due to greater lumbar curve