The composite effect reveals that human (but not other primate) faces are special to humans

Recognising faces is widely believed to be achieved using "special" neural and cognitive mechanisms that depend on "holistic" processing, which are not used when recognising other kinds of objects. An important, but largely unaddressed, question is how much like a Human face a stimulus needs to be to engage this "special" mechanism(s). In the current study, we attempted to answer this question in 3 ways. In Experiments 1 and 2 we examined the extent to which the disproportionate inversion effect for human faces extends to the faces of other species (including a range of other primates). Results suggested that the faces of other primates engage the mechanism responsible for the inversion effect approximately as well as that mechanism is engaged by Human faces, but that non-primate faces engage the mechanism less well. And so primate faces, in general, seem to produce a disproportionate inversion effect. In Experiment 3 we examined the extent to which the Composite effect extends to the faces of a range of other primates, and found no compelling evidence of a composite effect for the faces of any other primate. The composite effect was exclusive to Human faces. Because these data differ so dramatically from a previously reported study asking similar questions Taubert (2009), we also (in Experiment 4) ran an exact replication of Taubert's Experiment 2, which reported on both Inversion and Composite effects in a range of species. We were unable to reproduce the pattern of data reported by Taubert. Overall, the results suggest that the disproportionate inversion effect extends to all of the faces of the non-human primates tested, but that the composite effect is exclusive to Human faces.

Mate preference priorities in the East and West: A cross-cultural test of the mate preference priority model

OBJECTIVE

Mate choice involves trading-off several preferences. Research on this process tends to examine mate preference prioritization in homogenous samples using a small number of traits and thus provide little insight into whether prioritization patterns reflect a universal human nature. This study examined whether prioritization patterns, and their accompanying sex differences, are consistent across Eastern and Western cultures.

METHOD

In the largest test of the mate preference priority model to date, we asked an international sample of participants (N = 2,477) to design an ideal long-term partner by allocating mate dollars to eight traits using three budgets. Unlike previous versions of the task, we included traits known to vary in importance by culture (e.g., religiosity and chastity).

RESULTS

Under low budget conditions, Eastern and Western participants differed in their mate dollar allocation for almost every trait (average d = 0.42), indicating that culture influences prioritization. Despite these differences, traits fundamental for the reproductive success of each sex in the ancestral environment were prioritized by both Eastern and Western participants.

CONCLUSION

The tendency to prioritize reproductively fundamental traits is present in both Eastern and Western cultures. The psychological mechanisms responsible for this process produce similar prioritization patterns despite cross-cultural variation.

The role of mating context and fecundability in women's preferences for men's facial masculinity and beardedness

The ovulatory shift hypothesis proposes that women's preferences for masculine physical and behavioral traits are greater at the peri-ovulatory period than at other points of the menstrual cycle. However, many previous studies used self-reported menstrual cycle data to estimate fecundability rather than confirming the peri-ovulatory phase hormonally. Here we report two studies and three analyses revisiting the ovulatory shift hypothesis with respect to both facial masculinity and beardedness. In Study 1, a large sample of female participants (N = 2,161) self-reported their cycle phase and provided ratings for faces varying in beardedness (clean-shaven, light stubble, heavy stubble, full beards) and masculinity (-50%, -25%, natural, +25% and +50%) in a between-subjects design. In Study 2, 68 women provided the same ratings data, in a within-subjects design in which fertility was confirmed via luteinising hormone (LH) tests and analysed categorically. In Study 2, we also measured salivary estradiol (E) and progesterone (P) at the low and high fertility phases of the menstrual cycle among 36 of these women and tested whether shifts in E, P or E:P ratios predicted face preferences. Preferences for facial masculinity and beardedness did not vary as predicted with fecundability in Study 1, or with respect to fertility as confirmed via LH in Study 2. However, consistent with the ovulatory shift hypothesis, increasing E (associated with cyclical increases in fecundability) predicted increases in preferences for relatively more masculine faces; while high P (associated with cyclical decreases in fecundability) predicted increases in preferences for relatively more feminine faces. We also found an interaction between E and preferences for facial masculinity and beardedness, such that stubble was more attractive on un-manipulated than more masculine faces among women with high E. We consider discrepancies between our findings and those of other recent studies and suggest that closer scrutiny of the stimuli used to measure masculinity preferences across studies may help account for the many conflicting findings that have recently appeared regarding cycle phase preference shifts for facial masculinity.

Of Meat and Men: Sex Differences in Implicit and Explicit Attitudes Toward Meat

Modern attitudes to meat in both men and women reflect a strong meat-masculinity association. Sex differences in the relationship between meat and masculinity have not been previously explored. In the current study we used two IATs (implicit association tasks), a visual search task, and a questionnaire to measure implicit and explicit attitudes toward meat in men and women. Men exhibited stronger implicit associations between meat and healthiness than did women, but both sexes associated meat more strongly with 'healthy' than 'unhealthy' concepts. As 'healthy' was operationalized in the current study using terms such as "virile" and "powerful," this suggests that a meat-strength/power association may mediate the meat-masculinity link readily observed across western cultures. The sex difference was not related to explicit attitudes to meat, nor was it attributable to a variety of other factors, such as a generally more positive disposition toward meat in men than women. Men also exhibited an attention bias toward meats, compared to non-meat foods, while females exhibited more caution when searching for non-meat foods, compared to meat. These biases were not related to implicit attitudes, but did tend to increase with increasing hunger levels. Potential ultimate explanations for these differences, including sex differences in bio-physiological needs and receptivity to social signals are discussed.

The masculinity paradox: facial masculinity and beardedness interact to determine women's ratings of men's facial attractiveness

In many species, male secondary sexual traits have evolved via female choice as they confer indirect (i.e. genetic) benefits or direct benefits such as enhanced fertility or survival. In humans, the role of men's characteristically masculine androgen-dependent facial traits in determining men's attractiveness has presented an enduring paradox in studies of human mate preferences. Male-typical facial features such as a pronounced brow ridge and a more robust jawline may signal underlying health, whereas beards may signal men's age and masculine social dominance. However, masculine faces are judged as more attractive for short-term relationships over less masculine faces, whereas beards are judged as more attractive than clean-shaven faces for long-term relationships. Why such divergent effects occur between preferences for two sexually dimorphic traits remains unresolved. In this study, we used computer graphic manipulation to morph male faces varying in facial hair from clean-shaven, light stubble, heavy stubble and full beards to appear more (+25% and +50%) or less (-25% and -50%) masculine. Women (N = 8520) were assigned to treatments wherein they rated these stimuli for physical attractiveness in general, for a short-term liaison or a long-term relationship. Results showed a significant interaction between beardedness and masculinity on attractiveness ratings. Masculinized and, to an even greater extent, feminized faces were less attractive than unmanipulated faces when all were clean-shaven, and stubble and beards dampened the polarizing effects of extreme masculinity and femininity. Relationship context also had effects on ratings, with facial hair enhancing long-term, and not short-term, attractiveness. Effects of facial masculinization appear to have been due to small differences in the relative attractiveness of each masculinity level under the three treatment conditions and not to any change in the order of their attractiveness. Our findings suggest that beardedness may be attractive when judging long-term relationships as a signal of intrasexual formidability and the potential to provide direct benefits to females. More generally, our results hint at a divergence of signalling function, which may result in a subtle trade-off in women's preferences, for two highly sexually dimorphic androgen-dependent facial traits.

From the lab to the world: The paradigmatic assumption and the functional cognition of avian foraging

Mechanisms of animal learning and memory were traditionally studied without reference to niche-specific functional considerations. More recently, ecological demands have informed such investigations, most notably with respect to foraging in birds. In parallel, behavioural ecologists, primarily concerned with functional optimization, have begun to consider the role of mechanistic factors, including cognition, to explain apparent deviations from optimal predictions. In the present paper we discuss the application of laboratory-based constructs and paradigms of cognition to the real-world challenges faced by avian foragers. We argue that such applications have been handicapped by what we term the ‘paradigmatic assumption’ – the assumption that a given laboratory paradigm maps well enough onto a congruent cognitive mechanism (or cognitive ability) to justify conflation of the two. We present evidence against the paradigmatic assumption and suggest that to achieve a profitable integration between function and mechanism, with respect to animal cognition, a new conceptualization of cognitive mechanisms functional cognition – is required. This new conceptualization should define cognitive mechanisms based on the informational properties of the animal’s environment and the adaptive challenges faced. Cognitive mechanisms must be examined in settings that mimic the important aspects of the natural environment, using customized tasks designed to probe defined aspects of the mechanisms’ operation. We suggest that this approach will facilitate investigations of the functional and evolutionary relevance of cognitive mechanisms, as well as the patterns of divergence, convergence and specialization of cognitive mechanisms within and between species.

Threat is in the Sex of the Beholder: Men Find Weapons Faster than do Women

In visual displays, people locate potentially threatening stimuli, such as snakes, spiders, and weapons, more quickly than similar benign stimuli, such as beetles and gadgets. Such biases are likely adaptive, facilitating fast responses to potential threats. Currently, and historically, men have engaged in more weapons-related activities (fighting and hunting) than women. If biases of visual attention for weapons result from selection pressures related to these activities, then we would predict such biases to be stronger in men than in women. The current study reports the results of two visual search experiments, in which men showed a stronger bias of attention toward guns and knives than did women, whether the weapons were depicted wielded or not. When the weapons were depicted wielded, both sexes searched for them with more caution than when they were not. Neither of these effects extended reliably to syringes, a non-weapon—yet potentially threatening—object. The findings are discussed with respect to the “weapons effect” and social coercion theory.

Threat is in the sex of the beholder: men find weapons faster than do women

In visual displays, people locate potentially threatening stimuli, such as snakes, spiders, and weapons, more quickly than similar benign stimuli, such as beetles and gadgets. Such biases are likely adaptive, facilitating fast responses to potential threats. Currently, and historically, men have engaged in more weapons-related activities (fighting and hunting) than women. If biases of visual attention for weapons result from selection pressures related to these activities, then we would predict such biases to be stronger in men than in women. The current study reports the results of two visual search experiments, in which men showed a stronger bias of attention toward guns and knives than did women, whether the weapons were depicted wielded or not. When the weapons were depicted wielded, both sexes searched for them with more caution than when they were not. Neither of these effects extended reliably to syringes, a non-weapon-yet potentially threatening-object. The findings are discussed with respect to the "weapons effect" and social coercion theory.

Is There an Own-Race Preference in Attractiveness?

Even in multicultural nations interracial relationships and marriages are quite rare, one reflection of assortative mating. A relatively unexplored factor that could explain part of this effect is that people may find members of their own racial group more attractive than members of other groups. We tested whether there is an own-race preference in attractiveness judgments, and also examined the effect of familiarity by comparing the attractiveness ratings given by participants of different ancestral and geographic origins to faces of European, East Asian and African origin. We did not find a strong own-race bias in attractiveness judgments, but neither were the data consistent with familiarity, suggesting an important role for other factors determining the patterns of assortative mating observed.

Is there an own-race preference in attractiveness?

Even in multicultural nations interracial relationships and marriages are quite rare, one reflection of assortative mating. A relatively unexplored factor that could explain part of this effect is that people may find members of their own racial group more attractive than members of other groups. We tested whether there is an own-race preference in attractiveness judgments, and also examined the effect of familiarity by comparing the attractiveness ratings given by participants of different ancestral and geographic origins to faces of European, East Asian and African origin. We did not find a strong own-race bias in attractiveness judgments, but neither were the data consistent with familiarity, suggesting an important role for other factors determining the patterns of assortative mating observed.

The evolution of holistic processing of faces

In this paper we examine the holistic processing of faces from an evolutionary perspective, clarifying what such an approach entails, and evaluating the extent to which the evidence currently available permits any strong conclusions. While it seems clear that the holistic processing of faces depends on mechanisms evolved to perform that task, our review of the comparative literature reveals that there is currently insufficient evidence (or sometimes insufficiently compelling evidence) to decide when in our evolutionary past such processing may have arisen. It is also difficult to assess what kinds of selection pressures may have led to evolution of such a mechanism, or even what kinds of information holistic processing may have originally evolved to extract, given that many sources of socially relevant face-based information other than identity depend on integrating information across different regions of the face – judgments of expression, behavioral intent, attractiveness, sex, age, etc. We suggest some directions for future research that would help to answer these important questions.

Win-shift and win-stay learning in the rainbow lorikeet (Trichoglossus haematodus)

The tendency to win-shift (to better learn to avoid, rather than return to, recently rewarded locations) has been demonstrated in a variety of nectarivorous birds and in honeybees. It is hypothesized to be a cognitive adaptation to the depleting nature of nectar. In the present study we report the first attempt to test for a win-shift bias in a nectarivorous parrot, the rainbow lorikeet (Trichoglossus hematodus). This species differs from others tested for a win-shift bias in that it is a facultative, rather than an obligate, nectarivore. We tested a captive-reared population of the birds on a shift/stay task at long and short retention intervals. The data show no evidence of either a win-shift or a win-stay bias. The birds demonstrated efficient spatial search ability and above chance performance for both shift and stay contingencies at long and short delays. These data suggest that an innate tendency to win-shift may not be present in all avian nectarivores, or that the role experience plays in shaping such behaviors is different for different species.

A new viewpoint on the evolution of sexually dimorphic human faces

Human faces show marked sexual shape dimorphism, and this affects their attractiveness. Humans also show marked height dimorphism, which means that men typically view women's faces from slightly above and women typically view men's faces from slightly below. We tested the idea that this perspective difference may be the evolutionary origin of the face shape dimorphism by having males and females rate the masculinity/femininity and attractiveness of male and female faces that had been manipulated in pitch (forward or backward tilt), simulating viewing the face from slightly above or below. As predicted, tilting female faces upwards decreased their perceived femininity and attractiveness, whereas tilting them downwards increased their perceived femininity and attractiveness. Male faces tilted up were judged to be more masculine, and tilted down judged to be less masculine. This suggests that sexual selection may have embodied this viewpoint difference into the actual facial proportions of men and women.

A New Viewpoint on the Evolution of Sexually Dimorphic Human Faces

Human faces show marked sexual shape dimorphism, and this affects their attractiveness. Humans also show marked height dimorphism, which means that men typically view women's faces from slightly above and women typically view men's faces from slightly below. We tested the idea that this perspective difference may be the evolutionary origin of the face shape dimorphism by having males and females rate the masculinity/femininity and attractiveness of male and female faces that had been manipulated in pitch (forward or backward tilt), simulating viewing the face from slightly above or below. As predicted, tilting female faces upwards decreased their perceived femininity and attractiveness, whereas tilting them downwards increased their perceived femininity and attractiveness. Male faces tilted up were judged to be more masculine, and tilted down judged to be less masculine. This suggests that sexual selection may have embodied this viewpoint difference into the actual facial proportions of men and women.

When a place is not a place: encoding of spatial information is dependent on reward type

Abstract

The adaptationist perspective investigates how an animal's cognition has been shaped by the informational properties of the environment. The information that is useful may vary from one context to another. In the current study we examine how manipulating the foraging context (the type of resource being foraged) could affect the way spatial information is used by the forager. Noisy miner birds (omnivorous honeyeaters) were given spatial working memory tasks in which they searched baited and unbaited feeders for either nectar or invertebrates. We hypothesised that noisy miners would encode the locations of baited and unbaited feeders equally well when foraging for nectar (all flowers, whether containing nectar or not are places to remember and avoid while foraging on a plant). When foraging for invertebrates, however, we predicted that noisy miner birds would not encode the locations of unbaited feeders as effectively as baited feeders (in a natural patch of invertebrates there is no cue to differentiate a point location where a prey item has not been found from the rest of the potentially homogenous patch). As predicted, birds foraging for invertebrates made more revisits to unbaited than baited feeders, with no such difference evident when birds were foraging for nectar.

Search strategies of ants in landmark-rich habitats

Search is an important tool in an ant's navigational toolbox to relocate food sources and find the inconspicuous nest entrance. In habitats where landmark information is sparse, homing ants travel their entire home vector before searching systematically with ever increasing loops. Search strategies have not been previously investigated in ants that inhabit landmark-rich habitats where they typically establish stereotypical routes. Here we examine the search strategy in one such ant, Melophorus bagoti, by confining their foraging in one-dimensional channels to determine if their search pattern changes with experience, location of distant cues and altered distance on the homebound journey. Irrespective of conditions, we found ants exhibit a progressive search that drifted towards the fictive nest and beyond. Segments moving away from the start of the homeward journey were longer than segments heading back towards the start. The right tail distribution of segment lengths was well fitted by a power function, but slopes less than -3 on a log-log plot indicate that the process cannot be characterized as Lévy searches that have optimal slopes near -2. A double exponential function fits the distribution of segment lengths better, supporting another theoretically optimal search pattern, the composite Brownian walk.

Food-specific spatial memory biases in an omnivorous bird

The tendency of nectarivorous birds to perform better on tasks requiring them to avoid previously rewarding locations (to win-shift) than to return to them (win-stay) has been explained as an adaptation to the depleting nature of nectar. This interpretation relies on the previously untested assumption that the win-shift tendency is not associated with food types possessing a different distribution. To test this assumption, we examined the specificity of this bias to different food types in an omnivorous honeyeater, the noisy miner (Manorina melanocephala). As predicted, we found that the win-shift bias was sensitive to foraging context, manifesting only in association with foraging for nectar, not with foraging for invertebrates.