Children’s cross-cultural categorizations of racially ambiguous faces in Taiwan and the U.S.

Objectives: Racially ambiguous face categorization research is growing in prominence, and yet the majority of this work has focused on White and Western samples and has primarily used biracial Black/White stimuli. Past findings suggest that biracial Black/White faces are more often seen as Black than White, but without testing these perceptions with other groups, generalizability cannot be guaranteed. Methods: We tested 3-7-year old Asian children living in Taiwan—an Eastern cultural context (N = 74)—and Asian children living in the U.S.—a Western cultural context (N = 65) to explore the role that cultural group membership may play in biracial perceptions. Children categorized 12 racially ambiguous biracial Black/White faces and 12 biracial Asian/White faces in a dichotomous forced-choice task and completed a racial constancy measurement. Results: Regarding biracial Black/White faces, Taiwanese and Asian American children both categorized the faces as White significantly more often compared to chance levels, regardless of racial constancy beliefs. For biracial Asian/White faces, Taiwanese children with racial constancy beliefs categorized the faces significantly more often as White, whereas Taiwanese children without racial constancy beliefs categorized the faces significantly more often as Asian. However, Asian American children did not show a bias in categorizing biracial Asian/White faces. Conclusions: Results suggest that hyperdescent over hypodescent for more commonly studied biracial Black/White faces generalizes in both cultural contexts. However, biracial Asian/White stimuli may be perceived in more fixed-like patterns in predominately Asian contexts, since only Taiwanese children showed increased outgroup categorizations once racial constancy beliefs were endorsed.

Developmental Changes in Gaze Behavior and the Effects of Auditory Emotion Word Priming in Emotional Face Categorization

Social interactions often require the simultaneous processing of emotions from facial expressions and speech. However, the development of the gaze behavior used for emotion recognition, and the effects of speech perception on the visual encoding of facial expressions is less understood. We therefore conducted a word-primed face categorization experiment, where participants from multiple age groups (six-year-olds, 12-year-olds, and adults) categorized target facial expressions as positive or negative after priming with valence-congruent or -incongruent auditory emotion words, or no words at all. We recorded our participants’ gaze behavior during this task using an eye-tracker, and analyzed the data with respect to the fixation time toward the eyes and mouth regions of faces, as well as the time until participants made the first fixation within those regions (time to first fixation, TTFF). We found that the six-year-olds showed significantly higher accuracy in categorizing congruently primed faces compared to the other conditions. The six-year-olds also showed faster response times, shorter total fixation durations, and faster TTFF measures in all primed trials, regardless of congruency, as compared to unprimed trials. We also found that while adults looked first, and longer, at the eyes as compared to the mouth regions of target faces, children did not exhibit this gaze behavior. Our results thus indicate that young children are more sensitive than adults or older children to auditory emotion word primes during the perception of emotional faces, and that the distribution of gaze across the regions of the face changes significantly from childhood to adulthood.

The Face Module Emerged in a Deep Convolutional Neural Network Selectively Deprived of Face Experience

Can we recognize faces with zero experience on faces? This question is critical because it examines the role of experiences in the formation of domain-specific modules in the brain. Investigation with humans and non-human animals on this issue cannot easily dissociate the effect of the visual experience from that of the hardwired domain-specificity. Therefore, the present study built a model of selective deprivation of the experience on faces with a representative deep convolutional neural network, AlexNet, by removing all images containing faces from its training stimuli. This model did not show significant deficits in face categorization and discrimination, and face-selective modules automatically emerged. However, the deprivation reduced the domain-specificity of the face module. In sum, our study provides empirical evidence on the role of nature vs. nurture in developing the domain-specific modules that domain-specificity may evolve from non-specific experience without genetic predisposition, and is further fine-tuned by domain-specific experience.

Odor-driven face-like categorization in the human infant brain

Understanding how the young infant brain starts to categorize the flurry of ambiguous sensory inputs coming in from its complex environment is of primary scientific interest. Here, we test the hypothesis that senses other than vision play a key role in initiating complex visual categorizations in 20 4-mo-old infants exposed either to a baseline odor or to their mother’s odor while their electroencephalogram (EEG) is recorded. Various natural images of objects are presented at a 6-Hz rate (six images/second), with face-like object configurations of the same object categories (i.e., eliciting face pareidolia in adults) interleaved every sixth stimulus (i.e., 1 Hz). In the baseline odor context, a weak neural categorization response to face-like stimuli appears at 1 Hz in the EEG frequency spectrum over bilateral occipitotemporal regions. Critically, this face-like–selective response is magnified and becomes right lateralized in the presence of maternal body odor. This reveals that nonvisual cues systematically associated with human faces in the infant’s experience shape the interpretation of face-like configurations as faces in the right hemisphere, dominant for face categorization. At the individual level, this intersensory influence is particularly effective when there is no trace of face-like categorization in the baseline odor context. These observations provide evidence for the early tuning of face-(like)–selective activity from multisensory inputs in the developing brain, suggesting that perceptual development integrates information across the senses for efficient category acquisition, with early maturing systems such as olfaction driving the acquisition of categories in later-developing systems such as vision.

Rapid neural categorization of facelike objects predicts the perceptual awareness of a face (face pareidolia)

The human brain rapidly and automatically categorizes faces vs. other visual objects. However, whether face-selective neural activity predicts the subjective experience of a face – perceptual awareness – is debated. To clarify this issue, here we use face pareidolia, i.e., the illusory perception of a face, as a proxy to relate the neural categorization of a variety of facelike objects to conscious face perception. In Experiment 1, scalp electroencephalogram (EEG) is recorded while pictures of human faces or facelike objects – in different stimulation sequences – are interleaved every second (i.e., at 1 Hz) in a rapid 6-Hz train of natural images of nonface objects. Participants do not perform any explicit face categorization task during stimulation, and report whether they perceived illusory faces post-stimulation. A robust categorization response to facelike objects is identified at 1 Hz and harmonics in the EEG frequency spectrum with a facelike occipito-temporal topography. Across all individuals, the facelike categorization response is of about 20% of the response to human faces, but more strongly right-lateralized. Critically, its amplitude is much larger in participants who report having perceived illusory faces. In Experiment 2, facelike or matched nonface objects from the same categories appear at 1 Hz in sequences of nonface objects presented at variable stimulation rates (60 Hz to 12 Hz) and participants explicitly report after each sequence whether they perceived illusory faces. The facelike categorization response already emerges at the shortest stimulus duration (i.e., 17 ms at 60 Hz) and predicts the behavioral report of conscious perception. Strikingly, neural facelike-selectivity emerges exclusively when participants report illusory faces. Collectively, these experiments characterize a neural signature of face pareidolia in the context of rapid categorization, supporting the view that face-selective brain activity reliably predicts the subjective experience of a face from a single glance at a variety of stimuli.Highlights- EEG frequency-tagging measures the rapid categorization of facelike objects- Facelike objects elicit a facelike neural categorization response- Neural face categorization predicts conscious face perception across variable inputs