How Infants Categorize and Individuate Faces

This thesis evaluates whether young infants can (1) individuate and (2) categorize faces and (3) which process(es) will be elicited under which circumstances. Using the EEG technique, I tested categorization and individuation of human faces in 9-month-old infants. In a rapid repetition event-related potential (rrERP) study, 80 different faces were presented for 1.5 s each while controlling for low-level stimulus characteristics such as luminance or contrast (study 1). 9-month-old infants showed a reduced N290 latency for repeated compared to novel identities, thus demonstrating the ability to individuate unfamiliar faces. Regarding broader infant face categorization abilities, study 2 employs the Fast Periodic Visual Stimulation (FPVS) technique and provides a full evaluation of infants’ ability to categorize faces according to species. This includes generalization across faces of one species and discrimination between faces of different species. 9-month-old infants categorized faces according to species, and this effect was reduced for inverted faces. As 9-month-old infants are able to individuate and to categorize unfamiliar faces, I developed a framework that may allow predicting how infants will categorize a face under given circumstances. In a first evaluation of this framework, I have provided evidence that under relatively difficult processing circumstances, infants will categorize but not individuate faces (study 3). In this rrERP study, houses, ape faces and human faces were presented to infants for 1 s each, and repetition effects were observed on the basic (“human”, “monkey”) and superordinate (“faces”) levels. No difference was found between repeated and novel faces. Together, these studies show that by nine months of age, infants are able to categorize and individuate faces, and task and stimulus characteristics may drive them to perceive faces differently. Future work should complement this knowledge by testing infants throughout the first year of life while controlling for factors that may determine whether infants will categorize or individuate faces

Rapid Categorization of Human and Ape Faces in 9-Month-Old Infants Revealed by Fast Periodic Visual Stimulation

This study investigates categorization of human and ape faces in 9-month-olds using a Fast Periodic Visual Stimulation (FPVS) paradigm while measuring EEG. Categorization responses are elicited only if infants discriminate between different categories and generalize across exemplars within each category. In study 1, human or ape faces were presented as standard and deviant stimuli in upright and inverted trials. Upright ape faces presented among humans elicited strong categorization responses, whereas responses for upright human faces and for inverted ape faces were smaller. Deviant inverted human faces did not elicit categorization. Data were best explained by a model with main effects of species and orientation. However, variance of low-level image characteristics was higher for the ape than the human category. Variance was matched to replicate this finding in an independent sample (study 2). Both human and ape faces elicited categorization in upright and inverted conditions, but upright ape faces elicited the strongest responses. Again, data were best explained by a model of two main effects. These experiments demonstrate that 9-month-olds rapidly categorize faces, and unfamiliar faces presented among human faces elicit increased categorization responses. This likely reflects habituation for the familiar standard category, and stronger release for the unfamiliar category deviants

Editorial: Entrainment and responses to rhythmic stimulation during development

The editorial article is part of the Research Topic: Entrainment and Responses to Rhythmic Stimulation During Development.International audienc

ManyBabies 5: A large-scale investigation of the proposed shift from familiarity preference to novelty preference in infant looking time Pre-data collection manuscript for peer-review The ManyBabies 5 Team

International audienceMuch of our basic understanding of cognitive and social processes in infancy relies on measures of looking time, and specifically on infants' visual preference for a novel or familiar stimulus. However, despite being the foundation of many behavioral tasks in infant research, the determinants of infants' visual preferences are poorly understood, and differences in the expression of preferences can be difficult to interpret. In this large-scale study, we test predictions from the Hunter and Ames model of infants' visual preferences. 1 We investigate the effects of three factors predicted by this model to determine infants' preference for novel versus familiar stimuli: age, stimulus familiarity, and stimulus complexity. Drawing from a large and diverse sample of infant participants (N = XX), this study will provide crucial empirical evidence for a robust and generalizable model of infant visual preferences, leading to a more solid theoretical foundation for understanding the mechanisms that underlie infants' responses in common behavioral paradigms. Moreover, our findings will guide future studies that rely on infants' visual preferences to measure cognitive and social processes