Narrowing in categorical responding to other‐race face classes by infants

Infants can form object categories based on perceptual cues, but their ability to form categories based on differential experience is less clear. Here we examined whether infants filter through perceptual differences among faces from different other‐race classes and represent them as a single other‐race class different only from own‐race faces. We used a familiarization/novelty‐preference procedure to investigate category formation for two other‐race face classes (Black vs. Asian) by White 6‐ and 9‐month‐olds. The data indicated that while White 6‐month‐olds categorically represented the distinction between Black and Asian faces, White 9‐month‐olds formed a broad other‐race category inclusive of Black and Asian faces, but exclusive of own‐race White faces. The findings provide evidence that narrowing can occur for mental processes other than discrimination: category formation is also affected. The results suggest that frequency of experience with own‐race versus other‐race classes of faces may propel infants to contrast own‐race faces with other‐race faces, but not different classes of other‐race faces with each other.     

That’s the way the ball bounces: infants’ and adults’ perception of spatial and temporal contiguity in collisions involving bouncing balls

Three experiments investigated the perception of collisions involving bouncing balls by 7- and 10-month-old infants and adults. In previous research, 10-month-old infants perceived the causality of launching collisions (events in which one object moves along a smooth horizontal trajectory toward a second object, apparently launching it into motion) in relatively simple event contexts. In more complex event contexts, infants failed to discriminate among the events or respond to changes in individual features. Experiments 1 and 2 of the present investigation revealed that 7- and 10-month-old infants attended to spatial and temporal contiguity, but not causality, in collisions involving the movement of bouncing balls. In Experiment 3, both spatiotemporal contiguity and general knowledge about movement trajectories influenced adults’ judgments of causality for these collisions. The present results add to a growing understanding of infants’ event perception as constructive and a function, in part, of the complexity of the event context.     

4.5-month-old infants’ learning, retention and use of object boundary information

4.5-month-old infants can use information learned from prior experience with objects to help determine the boundaries of objects in a complex visual scene (Needham, 1998; Needham, Dueker, & Lockhead, 2002). The present studies investigate the effect of delay (between prior experience and test) on infant use of such experiential knowledge. Results indicate that infants can use experience with an object to help them to parse a scene containing that object 24 (Experiment 1). Experiment 2 suggests that after 24 h infants have begun to forget some object attributes, and that this forgetting promotes generalization from one similar object to another. After a 72-h delay, infants did not show any beneficial effect of prior experience with one of the objects in the scene (Experiments 3A and B). However, prior experience with multiple objects, similar to an object in the scene, facilitated infant segregation of the scene 72 h later, suggesting that category information remains available in infant memory longer than experience with a single object. The results are discussed in terms of optimal infant benefit from prior experiences with objects.     

Intermodal perception at birth: Intersensory redundancy guides newborn infants’ learning of arbitrary auditory−visual pairings

In this study the ability of newborn infants to learn arbitrary auditory–visual associations in the absence versus presence of amodal (redundant) and contingent information was investigated. In the auditory-noncontingent condition 2-day-old infants were familiarized to two alternating visual stimuli (differing in colour and orientation), each accompanied by its ‘own’ sound: when the visual stimulus was presented the sound was continuously presented, independently of whether the infant looked at the visual stimulus. In the auditory-contingent condition the auditory stimulus was presented only when the infant looked at the visual stimulus: thus, presentation of the sound was contingent upon infant looking. On the post-familiarization test trials attention recovered strongly to a novel auditory–visual combination in the auditory-contingent condition, but remained low, and indistinguishable from attention to the familiar combination, in the auditory-noncontingent condition. These findings are a clear demonstration that newborn infants’ learning of arbitrary auditory–visual associations is constrained and guided by the presence of redundant (amodal) contingent information. The findings give strong support to Bahrick’s theory of early intermodal perception.     

Face familiarity, distinctiveness, and categorical perception

Four experiments with faces support the original interpretation of categorical perception (CP) as only present for familiar categories. Unlike in the results of Levin and Beale (2000), no evidence is found for face identity CP with unfamiliar faces. Novel face identities were shown to be capable of encoding for immediate sorting purposes but the representations utilized do not have the format of perceptual categories. One possibility explored was that a choice of a distinctive face as an end-point in a morphed continuum can spuriously produce effects that resemble CP. Such morphed continua provided unequal psychological responses to equal physical steps though much more so in a better likeness paradigm than for forced-choice recognition. Thus, researchers doing almost the same experiments may produce very different results and come to radically different conclusions.     

Effects of Kindermusik training on infants’ rhythmic enculturation

Phillips‐Silver and Trainor (2005) demonstrated a link between movement and the metrical interpretation of rhythm patterns in 7‐month‐old infants. Infants bounced on every second beat of a rhythmic pattern with no auditory accents later preferred to listen to an accented version of the pattern with accents every second beat (duple or march meter), whereas infants bounced on every third beat of the same rhythmic pattern preferred to listen to a version with accents every third beat (triple or waltz meter). The present study compared infants participating in Kindermusik classes with infants not participating in music classes. In Kindermusik classes infants receive enriched experience moving to music. Following Western musical norms, the majority of the music samples in the classes are in duple meter. During the preference test, Kindermusik infants listened longer overall, indicating heightened interest in musical rhythms. Both groups listened longer to the accented version that matched how they had been bounced, but only the Kindermusik group showed a stronger preference in the case of duple bouncing than in the case of triple bouncing. We conclude that musical classes for infants can accelerate the development of culture‐specific metrical perception.     

An association between mothers’ speech clarity and infants’ speech discrimination skills

The quality of speech directed towards infants may play an important role in infants’ language development. However, few studies have examined the link between the two. We examined the correlation between maternal speech clarity and infant speech perception performance in two groups of Mandarin‐speaking mother–infant pairs. Maternal speech clarity was assessed using the degree of expansion of the vowel space, a measure previously shown to reflect the intelligibility of words and sentences. Speech discrimination in the infants (6–8 and 10–12‐month‐olds) was measured using a head‐turn task. The results show that mothers’ vowel space area is significantly correlated with infants’ speech discrimination performance. Socioeconomic data from both parents show that the result cannot be attributed to parental socioeconomic factors. This study is correlational and therefore a causal relationship cannot be firmly established. However, the results are consistent with the view that maternal speech clarity directly affects infants’ early language learning.     

Face familiarity,distinctiveness, and categorical perception

Four experiments with faces support the original interpretation of categorical perception (CP) as only present for familiar categories. Unlike in the results of Levin and Beale (2000) Levin, D. T. and Beale, J. M. 2000. Categorical perception occurs in newly learned faces, other-race faces, and inverted faces. Perception & Psychophysics, 62: 386–401. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar], no evidence is found for face identity CP with unfamiliar faces. Novel face identities were shown to be capable of encoding for immediate sorting purposes but the representations utilized do not have the format of perceptual categories. One possibility explored was that a choice of a distinctive face as an end-point in a morphed continuum can spuriously produce effects that resemble CP. Such morphed continua provided unequal psychological responses to equal physical steps though much more so in a better likeness paradigm than for forced-choice recognition. Thus, researchers doing almost the same experiments may produce very different results and come to radically different conclusions.     

Biracial and monoracial infant own‐race face perception: an eye tracking study

We know that early experience plays a crucial role in the development of face processing, but we know little about how infants learn to distinguish faces from different races, especially for non‐Caucasian populations. Moreover, it is unknown whether differential processing of different race faces observed in typically studied monoracial infants extends to biracial infants as well. Thus, we investigated 3‐month‐old Caucasian, Asian and biracial (Caucasian‐Asian) infants’ ability to distinguish Caucasian and Asian faces. Infants completed two within‐subject, infant‐controlled habituation sequences and test trials as an eye tracker recorded looking times and scanning patterns. Examination of individual differences revealed significant positive correlations between own‐race novelty preference and scanning frequency between eye and mouth regions of own‐race habituation stimuli for Caucasian and Asian infants, suggesting that facility in own‐race face discrimination stems from active inspection of internal facial features in these groups. Biracial infants, however, showed the opposite effect: An ‘own‐race’ novelty preference was associated with reduced scanning between eye and mouth regions of ‘own‐race’ habituation stimuli, suggesting that biracial infants use a distinct approach to processing frequently encountered faces. Future directions for investigating face processing development in biracial populations are discussed. A video abstract of this article can be viewed at http://youtu.be/a_dDXfFuEfY     

Spilling thoughts: configuring attentional resources in infants’ goal-directed actions

The focus and organization of attention in perception-action coupling is systematically examined in two studies involving 9 and 10 -month-old infants engaged in learning goal-directed behaviors. Experiment 1 (discrimination study) observed the influence of an attentionally demanding motor task on learning and cognition, while Experiment 2 (means-ends study) observed the influence of an attentionally demanding goal on motor planning and reaching performance. Taken together the results of these two experiments revealed that when mental processing resources were directed to thinking about movement, discrimination performance became compromised; conversely, when processing resources were directed to thinking about the goal-state, the motor planning and execution became compromised. These results suggest a “spilling forward” of thoughts onto actions and goal-states and thus an attention-driven cognition/action trade-off for infants’ goal-directed actions. Findings highlight the ultimate importance of emerging motor skills on cognition and are contextualized within the on-going dialogues and developmental debates surrounding perceptual-motor skill development and problem-solving strategies during the first year.     

Triadic interactions support infants’ emerging understanding of intentional actions

Infants’ understanding of the intentional nature of human action develops gradually across the first year of life. A key question is what mechanisms drive changes in this foundational social‐cognitive ability. The current studies explored the hypothesis that triadic interactions in which infants coordinate attention between a social partner and an object of mutual interest promote infants’ developing understanding of others as intentional agents. Infants’ spontaneous tendency to participate in triadic engagement was assessed in a semi‐structured play session with a researcher. Intentional action understanding was assessed by evaluating infants’ ability to visually predict the goal of an intentional reaching action. Study 1 (N = 88) revealed that 8‐ to 9‐month‐olds who displayed more bouts of triadic engagement showed better concurrent reasoning about the goal of an intentional reaching action. Study 2 (N = 114) confirmed these findings using a longitudinal design and demonstrated that infants who displayed more bouts of triadic engagement at 6–7 months were better at prospectively reasoning about the goal of an intentional reaching action 3 months later. Cross‐lagged path analyses revealed that intentional action understanding at 6–7 months did not predict later triadic engagement, suggesting that early triadic engagement supports later intentional action processing and not the other way around. Finally, evidence from both studies revealed the unique contribution of triadic over dyadic forms of engagement. These results highlight the importance of social interaction as a developmental mechanism and suggest that infants enrich their understanding of intentionality through triadic interactions with social partners.     

Dispersion in models of categorical perception

A signal detection theory model of auditory discrimination with a nonlinear mapping from stimulus continuum to perceptual continuum can account for the enhanced discrimination at the category boundary found in categorical perception. Properties of this transformation are specified by a unimodal “dispersion function”. Furthermore, it is shown that a system consisting of two acoustic feature detectors with an associated decision function is also a dispersive system, which models categorical perception of a stimulus continuum as well as boundary shifts under adaptation. The effect of detector adaptation on discrimination is discussed in view of three different types of decision variable and different types of detector noise.     

Identification of own-race and other-race faces: Implications for the representation of race in face space

Own-race faces are recognized more easily than faces of a different, unfamiliar race. According to the multidimensional space (MDS) framework, the poor discriminability of other-race faces is due to their being more densely clustered in face space than own-race faces. Multidimensional scaling analyses of similarity ratings (Caucasian participants, n = 22) showed that other-race (Chinese) faces are more densely clustered in face space. We applied a formal model to test whether the spatial location of face stimuli could account for identification accuracy of another group of Caucasian participants (n = 30). As expected, own-race (Caucasian) faces were identified more accurately (higher hit rate, lower false alarms, and higher A) than other-race faces, which were more densely clustered than ownrace faces. A quantitative model successfully predicted identification performance from the spatial locations of the stimuli. The results are discussed in relation to the standard MDS account of race effects and also an alternative “race-feature” hypothesis.     

Examining individual differences in infants’ habituation patterns using objective quantitative techniques

The assessment of individual differences in infant habituation patterns is important for answering basic questions about continuity in cognitive development. Nevertheless, there are flaws with existing methods for determining relevant parameters of the cognitive processes associated with habituation. In this paper, a more rigorous, model-based alternative approach is illustrated. The approach demonstrates how the habituation data of individual infants may be fit by specific functions, how habituation may be distinguished from random responding, and how the parameter estimates of individual infants’ habituation functions might be analyzed for meaningful subgroups or clusters. The model-based approach provides novel insights about individual subgroups when applied to a real habituation data set and thereby demonstrates the feasibility and utility of the techniques advocated.     

Infants’ Use of Functional Parts in Basic-like Categorization

An experiment with the sequential touching technique investigated the role of object parts on 1- to 2-year-old infants’ ability to form basic-level categories (cows and cars) from two different superordinate domains. Using the novel task design developed by Rakison and Butterworth, infants were tested with normal category exemplars as well as modified versions that were made by removing or attaching object parts (legs and wheels). Results revealed a developmental trend whereby infants’ use of object parts in categorization decreased with age. Analyses of infants’ functional responses (e.g. jumping or rolling) suggested that they might initially associate different kinds of object movement with different kinds of parts.