Male and female faces are only perceived categorically when linked to familiar identities – And when in doubt, he is a male

Abstract

Categorical perception (CP) is a fundamental cognitive process that enables us to sort similar objects in the world into meaningful categories with clear boundaries between them. CP has been found for high-level stimuli like human faces, more precisely, for the perception of face identity, expression and ethnicity. For sex however, which represents another important and biologically relevant dimension of human faces, results have been equivocal so far. Here, we reinvestigate CP for sex using newly created face stimuli to control two factors that to our opinion might have influenced the results in earlier studies. Our new stimuli are (a) derived from single face identities, so that changes of sex are not confounded with changes of identity information, and (b) "normalized" in their degree of maleness and femaleness, to counteract natural variations of perceived masculinity and femininity of faces that might obstruct evidence of categorical perception. Despite careful normalization, we did not find evidence of CP for sex using classical test procedures, unless participants were specifically familiarized with the face identities before testing. These results support the single-route hypothesis, stating that sex and identity information in faces are not processed in parallel, in contrast to what was suggested in the classical Bruce and Young model of face perception. Besides, interestingly, our participants show a consistent bias, before and after perceptual normalization of the male-female range of the test morph continua, to judge faces as male rather than female.

A Bayesian approach to person perception

“…The dissonance we experience while looking at this image indicates that we have strong expectations about the basic structural properties of a face that cannot help but influence our perception (see Hancock & Foster, 2012). Bülthoff, 2012;Cellerino, Borghetti, & Sartucci, 2004) that has also been reported in chimpanzees (de Waal & Pokorny, 2008). A similar 'male bias' has also been found for body shape (Johnson, Iida, & Tassinary, 2012), hands (Gaetano, van der Zwan, Blair, & Brooks, 2014) and biological motion (Troje, Sadr, Geyer, & Nakayama, 2006).…”

“…A similar 'male bias' has also been found for body shape (Johnson, Iida, & Tassinary, 2012), hands (Gaetano, van der Zwan, Blair, & Brooks, 2014) and biological motion (Troje, Sadr, Geyer, & Nakayama, 2006). It has been suggested that, in the history of humans, misclassifying a man as female has generally proved to be potentially more dangerous than misclassifying a woman as male (Armann & Bülthoff, 2012). A similar ''better safe than sorry'' heuristic has also been invoked in the context of the bias for direct gaze (Mareschal et al, 2013b) and other social judgments (Haselton & Nettle, 2006;Johnson et al, 2012).…”

“…Armann & Bülthoff, 2012;Webster, Kaping, Mizokami, & Duhamel, 2004). A heuristic bias underlying our judgments about another person's sex could in principle be implemented at either (or both) of these levels.…”

“…For example, when presented with an image of a face, there is a bias to respond 'male' when asked about that person's sex (e.g. Armann & Bülthoff, 2012) and to judge their age as closer to your own (e.g. Voelkle, Ebner, Lindenberger, & Riediger, 2012).…”

Categorical perception of familiarity: Evidence for a hyper-familiarity in schizophrenia

“…This type of task is based on the existence of the categorical perception effect, which occurs when the M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 8 perception of differences between categories is enhanced at the expense of our perception of incremental changes in the stimulus within a category (Pollak and Kistler, 2002). This categorical perception effect can be evidenced using an imaging-morphing procedure which consists of creating stimuli that vary along continua between discrete categories: (Kiffel et al, 2005, Angeli et al, 2008, Armann and Bülthoff, 2012. Referring to studies on categorical perception, we chose to use an identification task in which participants had to press a button when they felt familiar with the face that was presented.…”