A comparison of the literatures on how infants represent generic object classes, gender and race information in faces, and emotional expressions reveals both common and distinctive developments in the three domains. In addition, the review indicates that some very basic questions remain to be answered regarding how infants represent facial displays of emotion, including (a) whether infants form category representations for discrete classes of emotion, (b) when and how such representations come to incorporate affective meaning, (c) the developmental trajectory for (...) representation of emotional expression at different levels of inclusiveness (i.e., from broad to narrow or narrow to broad?), and (d) whether there is superior discrimination ability operating within more frequently experienced emotion categories. (shrink)

In this prcis we focus on phenomena central to the reaction against similarity-based theories that arose in the 1980s and that subsequently motivated the approach to semantic knowledge. Specifically, we consider (1) how concepts differentiate in early development, (2) why some groupings of items seem to form or coherent categories while others do not, (3) why different properties seem central or important to different concepts, (4) why children and adults sometimes attest to beliefs that seem to contradict their direct experience, (...) (5) how concepts reorganize between the ages of 4 and 10, and (6) the relationship between causal knowledge and semantic knowledge. The explanations our theory offers for these phenomena are illustrated with reference to a simple feed-forward connectionist model. The relationships between this simple model, the broader theory, and more general issues in cognitive science are discussed. (shrink)

This thesis evaluates whether young infants can individuate and categorize faces and which process 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 study, 80 different faces were presented for 1.5 s each while controlling for low-level stimulus characteristics such as luminance or contrast. 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 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. 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 and superordinate 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. (shrink)

This commentary considers the issues of what should be taken as evidence for semantic categorization in infants and why infants display a surprising asymmetry in the categorization of humans versus nonhuman animals. It is argued that perceptual knowledge should be viewed as a potent source of information for semantic categorization, and that the asymmetrical categorization behavior arises as a consequence of the frequency and similarity structure of experience.

Facial information is a powerful channel for human-to-human communication. Characteristically, faces can be defined as biological objects that are four-dimensional (4D) patterns, whereby they have concurrently a spatial structure as well as temporal dynamics. The spatial characteristics of facial objects possess three dimensions (3D), namely breadth, height and importantly, depth. The temporal properties of facial objects are defined by how a 3D facial structure evolves dynamically over time; where time is referred to as the fourth dimension (4D). Our entire perspective (...) of another’s face, whether it be social, affective or cognitive perceptions, is therefore built on a combination of 3D and 4D visual cues. Counterintuitively, over the past few decades of experimental research in psychology, facial stimuli have largely been presented to participants as a spatial pattern that has been flattened into two dimensions (2D), while remaining largely static. The following review aims to advance and update facial researchers, on the recent revolution in computer-generated, realistic 4D facial models produced from real-life human subjects. We delve in-depth to summarize recent studies which have utilized facial stimuli that possess 3D structural cues (geometry and depth) and 4D temporal cues (3D structure + dynamic viewpoint and movement). In sum, we have found that higher-order perceptions such as identity, gender, ethnicity, emotion and personality, are critically influenced by the 4D characteristics embedded within natural human faces. In future, it is recommended that facial stimuli incorporate the 4D space-time perspective with the proposed time-resolved methods. (shrink)