Context-specificity in facial cues of leadership

Facial cues can have context-contingent effects on leadership judgments, with dominant-looking individuals judged as better leaders in wartime than peacetime contexts and trustworthy-looking individuals judged as better leaders in peacetime than wartime contexts. To further explore this issue participants rated faces for dominance, trustworthiness, attractiveness, effectiveness as leader of a country during wartime or peacetime, and effectiveness as leader of a company manufacturing cars or clothing. Principal component analysis of potential leaders’ characteristics that predicted leadership judgments in prior research produced three components, reflecting general positive regard, dominance, and height, respectively. Perceived dominance and actual height positively predicted leadership judgments in a wartime context but not in a peacetime context. Positive regard positively predicted leadership judgments in a peacetime context, but not in a wartime context. Similar patterns of results were observed for leadership judgments in car manufacturing and clothing-manufacturing contexts. Together, these results present further evidence for context-contingent effects of facial cues on hypothetical leadership judgments

Third-party kinship recognition

Research into third party kinship recognition has been sparse even though kinship provides crucial insight into the biological underpinnings of pro-social and sexual behaviour. Furthermore, the studies that have been conducted are of varying quality and consistency, resulting in a myriad of different findings and conclusions. My doctoral research addressed the common issues in the literature by conducting studies using high quality stimuli, a consistent methodology and appropriate analyses. Study 1 investigated what facial information is used for making kinship judgments in 3D facial images, specifically the contribution of face shape and surface reflectance information (e.g., skin texture, tone, eye and eyebrow colour). Using binomial logistic mixed models, we found that participants were able to detect relatedness at levels above chance for all three stimulus versions. Overall, both individual shape and surface reflectance information contribute to kinship detection, and both cues are optimally combined when presented together. Study 2 investigated whether a smiling facial expression increases the accuracy of judging relatedness compared to a neutral facial expression in human raters. Contrary to expectations, smiling decreased the accuracy of relatedness judgments compared to a neutral facial expression. Study 3 aimed to replicate previous studies suggesting that birth order affects kinship detection ability. Our findings indicate that laterborns do not have an advantage in detecting child sibling pairs and that kinship judgment accuracy is therefore unaffected by rater birth order. Study 4 compared the performance of participants across three commonly used methods (i.e., kinship judgment, similarity rating, matching paradigm), using the same highly-controlled stimulus set. We found that while responses on all three tasks were correlated, performance varied significantly across the tasks. Furthermore, when looking at the effect sex and age of the portrayed individuals had on performance, we found that different results are found dependent on which method is used

Preregistered direct replication of "Sick body, vigilant mind: the biological immune system activates the behavioral immune system"

The tendency to attend to and avoid cues to pathogens varies across individuals and contexts. Researchers have proposed that this variation is partially driven by immunological vulnerability to infection, though support for this hypothesis is equivocal. One key piece of evidence (Miller & Maner, 2011) shows that participants who have recently been ill—and hence may have a reduced ability to combat subsequent infection—allocate more attention to faces with infectious-disease cues than do participants who have not recently been ill. The current article describes a direct replication of this study using a sample of 402 individuals from the University of Michigan, the University of Glasgow, and Vrije Universiteit Amsterdam—more than 4 times the sample size of the original study. No effect of illness recency on attentional bias for disfigured faces emerged. Though it did not support the original finding, this replication provides suggestions for future research on the psychological underpinnings of pathogen avoidance

Contribution of shape and surface reflectance information to kinship detection in 3D face images

Previous research has established that humans are able to detect kinship among strangers from facial images alone. The current study investigated what facial information is used for making those kinship judgments, specifically the contribution of face shape and surface reflectance information (e.g., skin texture, tone, eye and eyebrow color). Using 3D facial images, 195 participants were asked to judge the relatedness of 100 child pairs, half of which were related and half of which were unrelated. Participants were randomly assigned to judge one of three stimulus versions: face images with both surface reflectance and shape information present (reflectance and shape version), face images with shape information removed but surface reflectance present (reflectance version), or face images with surface reflectance information removed but shape present (shape version). Using binomial logistic mixed models, we found that participants were able to detect relatedness at levels above chance for all three stimulus versions. Overall, both individual shape and surface reflectance information contribute to kinship detection, and both cues are optimally combined when presented together. Preprint, preregistration, code, and data are available on the Open Science Framework (osf.io/7ftxd)

Birth order does not affect ability to detect kin

Previous studies suggest that birth order affects kinship detection ability. Kaminski et al. (2010) argued that firstborns use contextual cues (e.g., maternal perinatal association) to assess kinship in their own family, leading to a disadvantage in assessing kinship from facial cues alone in strangers. In contrast, laterborns do not have the contextual cue of maternal perinatal association and hence rely more on facial cues, leading to an advantage in detecting kin from facial cues alone. However, Alvergne et al. (2010) found no evidence in support of such a birthorder effect. The current study aimed to replicate previous studies with better suited methods to determine the effect of birth order on kin recognition. 109 raters viewed 132 pairs of photographs of children (aged 3-17 years), and indicated whether each pair was related or unrelated. Half of the pairs were sibling pairs and half were unrelated child pairs that were age- and gender- matched to the related pairs. No image was shown more than once, related pairs were not known to be related to any other image in the study, and individuals from unrelated pairs were not known to be related to any other image. We used binomial logistic mixed effects modelling to predict kinship judgments from relatedness and birth order (with image pair and rater as random factors). Relatedness was the main factor driving kinship judgments; related child-pairs were more than twice as likely as unrelated pairs to be judged as kin. Kinship judgment accuracy was unaffected by rater birth order. These findings indicate that laterborns did not have an advantage in detecting child sibling pairs. Pre-registration, data, code, and preprint available at osf.io/h43ep

Kin recognition and perceived facial similarity

Facial similarity between individuals informs kinship judgments in third-party kin recognition. Indeed, one study found that similarity and kinship judgments encapsulate the same information (Maloney & Dal Martello, 2006). Yet, another study found that this is not the case when comparing adult face pairs of different sex (DeBruine et al., 2009). We replicated these studies to further clarify the role of facial similarity in kin recognition. We recruited 318 raters, who were shown 50 sibling pairs and 50 age- and sex-matched unrelated pairs ranging from 3 to 17 years old. Each rater was randomly assigned to make either kinship judgments (“related” or “unrelated”) or similarity judgments (scale from 0 [not very similar] to 10 [very similar]). The threshold model found that performance in both tasks was equally accurate, with participants detecting child siblings in the kinship task above chance and giving significantly higher similarity ratings to siblings in the similarity task. In both tasks, opposite-sex siblings were perceived to be siblings less often than same-sex siblings, and judgments of unrelated face pairs were not affected by the sex of faces. Conversely, the effect of age difference within pairs of faces differed for the two tasks: a greater age difference decreased all kinship judgments, but only decreased similarity judgments of siblings, not unrelated pairs. In line with DeBruine et al. (2009), these findings suggest that similarity and kinship judgments are highly correlated but not strictly synonymous. The OSF Pre-registration Challenge for this project can be found at osf.io/ps9hy and the data at osf.io/sef9k

Facial expressions influence kin recognition accuracy

Kinship informs the allocation of pro-social and sexual behaviour. In addition to the ability to detect kin who are directly related to the observer, humans are also able to detect relatedness among others who are not related to themselves based on facial cues of relatedness. However, it is unclear what exact facial cues inform these kinship judgments. Facial expression might be one candidate, as it has been shown that a computer kin-detection algorithm can match relatives accurately when the stimuli are smiling. The current study investigated whether a smiling facial expression increases the accuracy of judging relatedness compared to a neutral facial expression in human raters. The stimuli were images of 50 sibling pairs and 50 unrelated pairs (aged 3-17 years) matched for age, ethnicity and sex. The stimuli included both neutral and smiling versions of each individual. Raters (N=77) were asked to judge whether the presented pairs were related or not in one of two counterbalanced versions of the study, where the same stimuli were never presented as both smiling and neutral to the same rater, and the expression within the pair was always the same. Binary relatedness judgments were analysed using binomial logistic mixed regression. Contrary to expectations, smiling decreased the accuracy of relatedness judgments compared to a neutral facial expression. When shown with a smiling expression compared to a neutral one, related pairs were judged to be related less often, while unrelated pairs were judged to be related more often. Evidence that the upper face is mostly used for kinship judgments suggests that smiles could distort or distract from other, more reliable cues of kinship. Pre-registration, data and code available at https://osf.io/58ewu/

Do 3D face images capture cues of strength, weight, and height better than 2D face images do?

Objectives: A large literature exists investigating the extent to which physical characteristics (e.g., strength, weight, and height) can be accurately assessed from face images. While most of these studies have employed two-dimensional (2D) face images as stimuli, some recent studies have used three-dimensional (3D) face images because they may contain cues not visible in 2D face images. As equipment required for 3D face images is considerably more expensive than that required for 2D face images, we here investigated how perceptual ratings of physical characteristics from 2D and 3D face images compare. Methods: We tested whether 3D face images capture cues of strength, weight, and height better than 2D face images do by directly comparing the accuracy of strength, weight, and height ratings of 182 2D and 3D face images taken simultaneously. Strength, height and weight were rated by 66, 59 and 52 raters respectively, who viewed both 2D and 3D images. Results: In line with previous studies, we found that weight and height can be judged somewhat accurately from faces; contrary to previous research, we found that people were relatively inaccurate at assessing strength. We found no evidence that physical characteristics could be judged more accurately from 3D than 2D images. Conclusion: Our results suggest physical characteristics are perceived with similar accuracy from 2D and 3D face images. They also suggest that the substantial costs associated with collecting 3D face scans may not be justified for research on the accuracy of facial judgments of physical characteristics

A data-driven study of Chinese participants' social judgments of Chinese faces

Social judgments of faces made by Western participants are thought to be underpinned by two dimensions: valence and dominance. Because some research suggests that Western and Eastern participants process faces differently, the two-dimensional model of face evaluation may not necessarily apply to judgments of faces by Eastern participants. Here we used a data-driven approach to investigate the components underlying social judgments of Chinese faces by Chinese participants. Analyses showed that social judgments of Chinese faces by Chinese participants are partly underpinned by a general approachability dimension similar to the valence dimension previously found to underpin Western participants’ evaluations of White faces. However, we found that a general capability dimension, rather than a dominance dimension, contributed to Chinese participants’ evaluations of Chinese faces. Thus, our findings present evidence for both cultural similarities and cultural differences in social evaluations of faces. Importantly, the dimension that explained most of the variance in Chinese participants’ social judgments of faces was strikingly similar to the valence dimension previously reported for Western participants