Multiple group membership influences face-recognition: Recall and neurological evidence

The limited face-recognition research involving targets categorizable on multiple dimensions has provided contradictory evidence as to how partial-ingroup members are processed and recognized. This research demonstrates that partial-ingroup members are recognized in a manner distinct from double-ingroup and double-outgroup targets. Specifically, when race and university-affiliation are crossed, university-affiliation does not influence recognition for own-race targets, but does for other-race targets, in that other-race/own-university targets are recalled more accurately than other-race/other-university targets. The neurological mechanisms involved in the effect are explored through the inclusion of electroencephalography.     

Computational and performance aspects of PCA-based face-recognition algorithms

Algorithms based on principal component analysis (PCA) form the basis of numerous studies in the psychological and algorithmic face-recognition literature. PCA is a statistical technique and its incorporation into a face-recognition algorithm requires numerous design decisions. We explicitly state the design decisions by introducing a generic modular PCA-algorithm. This allows us to investigate these decisions, including those not documented in the literature. We experimented with different implementations of each module, and evaluated the different implementations using the September 1996 FERET evaluation protocol (the de facto standard for evaluating face-recognition algorithms). We experimented with (i) changing the illumination normalization procedure; (ii) studying effects on algorithm performance of compressing images with JPEG and wavelet compression algorithms; (iii) varying the number of eigenvectors in the representation; and (iv) changing the similarity measure in the classification process. We performed two experiments. In the first experiment, we obtained performance results on the standard September 1996 FERET large-gallery image sets. In the second experiment, we examined the variability in algorithm performance on different sets of facial images. The study was performed on 100 randomly generated image sets (galleries) of the same size. Our two most significant results are (i) changing the similarity measure produced the greatest change in performance, and (ii) that difference in performance of +/- 10% is needed to distinguish between algorithms.     

Infants' understanding of actions performed by mechanical devices

Recent research suggests that 9-month-old infants tested in a modified version of the A-not-B search task covertly imitate actions performed by the experimenter. The current study examines whether infants also simulate actions performed by mechanical devices, and whether this varies with whether or not they have been familiarized with the devices and their function. In Experiment 1, infants observed hiding and retrieving actions performed by a pair of mechanical claws on the A-trials, and then searched for the hidden toy on the B-trial. In Experiment 2, infants were first familiarized with the experimenter and the claws but not their function. In Experiment 3, infants were familiarized with the function of the claws. The results revealed that search errors were at chance levels in Experiments 1 and 2, but a significant proportion of the infants showed the A-not-B error in Experiment 3. These results suggest that 9-month-old infants are less likely to simulate observed actions performed by mechanical devices than by human agents, unless they are familiarized with the function of the devices so that their actions are perceived as goal-directed.     

Infants' discrimination of faces by using biological motion cues

We report two experiments in which we used animated averaged faces to examine infants' ability to perceive and discriminate facial motion. The faces were generated by using the motion recorded from the faces of volunteers while they spoke. We tested infants aged 4-8 months to assess their ability to discriminate facial motion sequences (condition 1) and discriminate the faces of individuals (condition 2). Infants were habituated to one sequence with the motion of one actor speaking one phrase. Following habituation, infants were presented with the same sequence together with motion from a different actor (condition 1), or a new sequence from the same actor coupled with a new sequence from a new actor (condition 2). Infants demonstrated a significant preference for the novel actor in both experiments. These findings suggest that infants can not only discriminate complex and subtle biological motion cues but also detect invariants in such displays.     

Infants' tracking of objects and collections

Recent research suggests that infants' understanding of the physical world is more complex and adult-like than previously believed. One of the most impressive discoveries has been infants' ability to reason about medium-sized, material objects. They are able to individuate objects in a scene, and to enumerate and reason about them. This article reports a series of experiments investigating 8-month-old infants' ability to reason about collections of objects. Experiment 1 shows a sharp contrast between infants' understanding of single objects versus collections. While infants detected the discontinuous ('Magical') disappearance of a single object, they did not detect the Magical Disappearance of a non-cohesive pile of objects. Experiments 2-4 found that infants' difficulty remained even when the distinct identity of each object in the collection was emphasized, but could be overcome if infants (a) first saw the individual objects clearly separated from each other prior to their being placed together in a pile, or (b) had prior experience with the objects making up the collection. Our findings suggest that infants' expectations about object behavior are highly specific regarding the entities they are applied to. They do not automatically apply to any and all portions of matter within the visual field. Both the behavior of an entity, and infants' prior experience play roles in determining whether infants will treat that entity as an object.     

Infants' delayed recognition memory and forgetting

Infants 21- to 25-weeks-old devoted more visual fixation to novel than to previously exposed stimuli on immediate and delayed tests of recognition. Abstract black and white patterns were recognized following a 48-hour delay and photos of faces after a 2-week delay. A decline in recognition over 3 hours for targets (face masks) most akin to objects (real faces) in S's environment led to studies of the effect on delayed recognition of exposure to stimuli similar to those to be retained. One-minute delayed recognition for face photos was disrupted by intervening exposure to intermediate similarity stimuli (rotated photos) but was unaffected by exposure to either high (upright photos) or low (rotated line drawings) similarity stimuli. Differentiation among intervening stimuli occurred only for the upright photos used as high-similarity intervening material. In addition, immediate exposure to rotated photos also prevented 3-hour-delayed recognition of upright photos but had no such effect when delayed for 3 hours. The present experiments confirm the existence of long-term recognition memory for pictorial stimuli in the early months of life and show that one source of forgetting is due to a diversion of the infant's attention to material bearing some perceptual similarity to the material to be retained. This diversion of attention must occur soon after immediate recognition testing to produce a reduction of recognition and such deleterious effects last for an appreciable period of time.     

Infants' discrimination of happy and sad music

Infants can detect information specifying affect in infant- and adult-directed speech, familiar and unfamiliar facial expressions, and in point-light displays of facial expressions. We examined 3-, 5-, 7-, and 9-month-olds' discrimination of musical excerpts judged by adults and preschoolers as happy and sad. In Experiment 1, using an infant-controlled habituation procedure, 3-, 5-, 7-, and 9-month-olds heard three musical excerpts that were rated as either happy or sad. Following habituation, infants were presented with two new musical excerpts from the other affect group. Nine-month-olds discriminated the musical excerpts rated as affectively different. Five- and seven-month-olds discriminated the happy and sad excerpts when they were habituated to sad excerpts but not when they were habituated to happy excerpts. Three-month-olds showed no evidence of discriminating the sad and happy excerpts. In Experiment 2, 5-, 7-, and 9-month-olds were presented with two new musical excerpts from the same affective group as the habituation excerpts. At no age did infants discriminate these novel, yet affectively similar, musical excerpts. In Experiment 3, we examined 5-, 7-, and 9-month-olds' discrimination of individual excerpts rated as affectively similar. Only the 9-month-olds discriminated the affectively similar individual excerpts. Results are discussed in terms of infants' ability to discriminate affect across a variety of events and its relevance for later social-communicative development.     

Infants' individuation of agents and inert objects

Using the violation-of-expectancy method, we investigated 10-month-old infants' ability to rely on dynamic features in object individuation processes. Infants were first familiarized to events in which two different objects repeatedly appeared and disappeared, one at a time from behind a screen; at test, the screen was removed, revealing either one or two objects. In Experiment 1, one self-moving non-rigid agent and one inert object were involved in each trial, while in Experiment 2 two different agents were presented. Infants preferred to look at one-object outcomes in Experiment 1, but they did not show any preference for one- or two-object outcomes in Experiment 2. The results suggest that infants can use dynamic information to detect agents in complex individuation tasks before they can rely on shape or surface features. We propose that the sortals agent and inert object appear in development before 12 months without a substantial contribution of linguistic experience. These findings may motivate a revision of current theories on the development of kind-based individuation and object files.     

Infants' attention to intrastimulus motion

Twenty-four 5-week-old infants sucked significantly less when shown a schematic face in which the eye dots oscillated at 4 or 7 cm/sec than when shown the same face with the eye dots oscillating at 1 cm/sec. When identical moving dots were presented in the absence of the surrounding facial configuration, infants showed the same pattern of response. These results indicate (a) that 5-week-old infants can attend to intrastimulus movement, and (b) that the “externality effect” does not extend to compound visual displays which have moving internal elements.     

Infants' Grasp of Others' Intentions

ABSTRACT— The perception of others as intentional agents is fundamental to human experience and foundational to development. Recent research reveals that this cornerstone of social perception has its roots early in infancy, and that it is influenced by the universal, early-emerging human experience of engaging in goal-directed action. Infants' own action capabilities correlate with their emerging tendency to view others' actions as organized by goals. Moreover, interventions that facilitate new goal-directed actions alter infants' perception of those same actions in others. These effects seem to depend on the first-person aspects of infants' experience. These findings open new questions about how doing leads to knowing in the social domain.     

Infants' behavior with their mothers and grandmothers

Grandparents are a relatively neglected part of children's social network. In order to look at attachment behavior of young children toward their grandmothers, the present study examined infants' behavior in a play-separation situation with their mothers and maternal grandmothers. In a series of 13 3-min segments, mothers, grandmothers, and strangers were signaled in turn to leave the room and to return. The infants' (N=30) playroom behavior was examined by measuring duration of play, cry, proximity to each adult, hold by each adult, and proximity to the door. In this situation, mothers and grandmothers were treated almost interchangeably, while strangers were treated as strangers. These findings did not vary by amount of contact (from daily to twice a month), age of infant (12 to 24 months), or “birth order” of the grandchild. The findings may be specific to middle-class, stable families in which the grandmother lives nearby and has frequent contact with the grandchild. From these data, grandmother is seen as one who can serve some of the same functions as an attachment figure and who is able to play an important role in the young child's social development.     

Infants' social withdrawal and parents' mental health

This study examined the association of infants' sustained social withdrawal with parents' self-reported current depressive symptoms and perceived mental health. Two hundred and sixty infants aged 4, 8 and 18 months were examined with the Baby Alarm Distress Scale (ADBB). Parents' depressive symptoms and perceived mental health during the preceding year were elicited through questionnaires. Mother's current depressive symptoms and father's perceived moderate or poor mental health during the preceding year both independently increased the infant's risk of withdrawal. When both parents had mental health problems, the infant was more likely to be withdrawn. Infant's social withdrawal should alert clinicians to examine parental mental health. Also, if the parent has mental health problems, the infant's social behavior and possible withdrawal should be examined. Families where both parents experience poor mental health should be identified, and treated, while the infants of these families in particular seem to be at risk for social withdrawal.     

Infants' and adults' perception of scale structure.

Adults and 9-month-old infants were required to detect mistuned tones in multitone sequences. When 7-tone versions of a common nursery tune were generated from the Western major scale (unequal scale steps) or from an alternative scale (equal steps), infants detected the mistuned tones more accurately in the unequal-step context than in the equal-step context (Experiment 1). Infants and adults were subsequently tested with 1 of 3 ascending-descending scales (15 tones): (a) a potentially familiar scale (major) with unequal steps, (b) an unfamiliar scale with unequal steps, and (c) an unfamiliar scale with equal steps. Infants detected mistuned tones only in the scales with unequal steps (Experiment 2). Adults performed better on the familiar (major) unequal-step scale and equally poorly on both unfamiliar scales (Experiments 3 and 4). These findings are indicative of an inherent processing bias favoring unequal-step scales.     

Infants' Differential Processing of Female and Male Faces

ABSTRACT— Infants show an interesting asymmetry in face processing: They are more fluent in processing female faces than they are at processing male faces. We hypothesize that such processing asymmetry results from greater experience with female faces than with male faces early in development. Asymmetrical face processing may have long-lasting implications for development of face recognition, development of knowledge structures regarding females and males, and social-information processing. We encourage researchers to use both female and male faces in their face-perception research and to conduct separate analyses for female and male faces.     

Infants' delayed recognition memory for colour and form

Delayed recognition memory was investigated in 5- and 9-week-old infants after extensive familiarization to a visual stimulus. Both age groups were found to demonstrate memory for colour and form information after a 24 hour delay. In addition the location of testing, relative to the location of familiarization, was found to influence the apparent strength of memory, while there was no effect of sex nor evidence of additivity of stimulus dimensions.