Eye tracking provides no evidence that young infants understand path obstruction.

In two experiments with 47 4-month-olds, we investigated attention to key aspects of events in which an object moved along a partly occluded path that contained an obstruction. Infants were familiarized with a ball rolling behind an occluder to be revealed resting on an end wall, and on test trials an obstruction wall was placed in the ball's path. In Experiment 1, we did not find longer looking when the object appeared in an impossible location beyond the obstruction, and infants did not selectively fixate the object in this location. In Experiment 2, after rolling one or two balls, we measured infants' fixations of a two-object outcome with one ball in a novel but possible resting position and the other in a familiar but impossible location beyond the obstruction. Infants looked longer at the ball in the possible but novel location, likely reflecting a looking preference for location novelty. Thus we obtained no evidence that infants reasoned about obstruction and identified a violation on that basis.

Infancy studies come of age: Jacques Mehler's influence on the importance of perinatal experience for early language learning.

In this paper, we pay homage to Jacques Mehler's empirical and theoretical contributions to the field of infancy studies. We focus on studies of the ability of the human fetus and newborn to attend to, learn from, and remember aspects of the environment, in particular the linguistic environment, as a part of an essential dynamic system of early influence. We provide a selective review of Mehler's and others' studies that examined the perinatal period and helped to clarify the earliest skills and predilections that infants bring to the task of language learning. We then highlight findings on newborns' perceptual skills and biases that motivated a shift in researchers' focus to fetal learning to better understand the role of the maternal voice in guiding newborns' speech perception. Finally, we point to the inspiration drawn from these perinatal approaches to more full-scale empirical treatments of how prenatal experience and behavior have come to be recognized as essential underpinnings to the earliest mental architectures of human cognition.

Orientation Effects in the Development of Linear Object Tracking in Early Infancy.

Infants' oculomotor tracking develops rapidly but is poorer when there are horizontal and vertical movement components. Additionally, persistence of objects moving through occlusion emerges at 4 months but initially is absent for objects moving obliquely. In two experiments, we recorded eye movements of thirty-two 4-month-old and thirty-two 6-month-old infants (mainly Caucasian-White) tracking horizontal, vertical, and oblique trajectories. Infants tracked oblique trajectories less accurately, but 6-month olds tracked more accurately such that they tracked oblique trajectories as accurately as 4-month olds tracked horizontal and vertical trajectories. Similar results emerged when the object was temporarily occluded. Thus, 4-month olds' tracking of oblique trajectories may be insufficient to support object persistence, whereas 6-month olds may track sufficiently accurately to perceive object persistence for all trajectory orientations.

Development of the other-race effect in Malaysian-Chinese infants.

Little is known about how infants born and raised in a multiracial environment process own- and other-race faces. We investigated face recognition of 3- to 4-month-old (N = 36) and 8- to 9-month-old (N = 38) Chinese infants from Kuala Lumpur, Malaysia, a population that is considered multiracial, using female and male faces that are of infants' own-race (Chinese), experienced other-race (Malay) and less experienced other-race (Caucasian-White). Three- to 4-month-olds recognized own-race female faces, whereas 8- to 9-month-olds also recognized experienced other-race female faces (Malay) in addition to own-race female faces (Chinese). Furthermore, infants from this population did not show recognition for male faces at any age. This contrasts with 8- to 9-month-old British-White infants (Tham, Bremner, & Hay, ), a group that is considered single-race, who recognized female and male own-race faces. It appears that for infants born and raised in a multiracial environment, there is a developmental shift from a female-based own-race recognition advantage to a female-based own- and experienced other-race advantage that may relate to infants' social and caregiving experiences.

Auditory information for spatial location and pitch-height correspondence support young infants' perception of object persistence.

Perception of object persistence across occlusion emerges at around 4 months of age for objects moving horizontally or vertically. In addition, congruent auditory information for movement enhances perception of persistence of an object moving horizontally. In two experiments, we examined the effect of presenting bimodal (visual and auditory) sensory information, both congruently and incongruently, for a vertical moving object occlusion event. A total of 68 4-month-old infants (34 girls) were tested for perception of persistence of an object moving up and down, passing at each translation behind a centrally placed occluder. Infants were exposed to these visual events accompanied by no sound, spatially colocated sound, or congruent or incongruent pitch-height correspondence sounds. Both spatially colocated and congruent pitch-height auditory information enhanced perception of trajectory continuity. However, no impairment occurred when pitch-height sound information was presented incongruently. These results highlight the importance of taking a multisensory approach to infant perceptual development.

Young infants' visual fixation patterns in addition and subtraction tasks support an object tracking account.

Investigating infants' numerical ability is crucial to identifying the developmental origins of numeracy. Wynn (1992) claimed that 5-month-old infants understand addition and subtraction as indicated by longer looking at outcomes that violate numerical operations (i.e., 1+1=1 and 2-1=2). However, Wynn's claim was contentious, with others suggesting that her results might reflect a familiarity preference for the initial array or that they could be explained in terms of object tracking. To cast light on this controversy, Wynn's conditions were replicated with conventional looking time supplemented with eye-tracker data. In the incorrect outcome of 2 in a subtraction event (2-1=2), infants looked selectively at the incorrectly present object, a finding that is not predicted by an initial array preference account or a symbolic numerical account but that is consistent with a perceptual object tracking account. It appears that young infants can track at least one object over occlusion, and this may form the precursor of numerical ability.

Limits of Object Persistence: Young Infants Perceive Continuity of Vertical and Horizontal Trajectories, But Not 45-Degree Oblique Trajectories.

Previous research indicated that 4-month-old infants perceive continuity of objects moving on horizontal trajectories but appear to have difficulty processing occlusion events involving oblique trajectories. However, because perception of continuity of vertical trajectories has not been tested, it is uncertain whether this indicates a specific deficit for oblique trajectories or a specific advantage for horizontal trajectories. We evaluated the contribution of trajectory orientation and the form of occlusion in three experiments with one hundred and forty-four 4-month-olds. Infants perceived continuity of horizontal and vertical trajectories under all conditions presented. However, they did not perceive continuity of an oblique (45°) trajectory under any condition. Thus, 4-month-olds appear unable to process continuity of a 45° trajectory. In a fourth experiment with forty-eight 6- and 8-month-old infants, we demonstrated that by 6 months, infants' difficulty with oblique trajectories is overcome. We suggest that young infants' difficulty with markedly oblique trajectories likely relates to immature eye movement control.

The other-race effect in children from a multiracial population: A cross-cultural comparison.

The role of experience with other-race faces in the development of the other-race effect was investigated through a cross-cultural comparison between 5- and 6-year-olds and 13- and 14-year-olds raised in a monoracial (British White, n=83) population and a multiracial (Malaysian Chinese, n=68) population. British White children showed an other-race effect to three other-race faces (Chinese, Malay, and African Black) that was stable across age. Malaysian Chinese children showed a recognition deficit for less experienced faces (African Black) but showed a recognition advantage for faces of which they have direct or indirect experience. Interestingly, younger (Malaysian Chinese) children showed no other-race effect for female faces such that they can recognize all female faces regardless of race. These findings point to the importance of early race and gender experiences in reorganizing the face representation to accommodate changes in experience across development.

Investigating looking and social looking measures as an index of infant violation of expectation.

Accumulated looking time has been widely used to index violation of expectation (VoE) response in young infants. But there is controversy concerning the validity of this measure, with some interpreting infant looking behaviour in terms of perceptual preferences (Cohen & Marks, ; Haith, ). The current study aimed to compare the use of looking time with a recently used measure of social looking (Walden et al., ) in distinguishing between 6-month-old infants' response to novelty/familiarity and a condition in which the object was covertly switched for a different object. Following habituation, infants showed more social looking in response to the object-switch condition than the novel object change, whereas the more commonly used accumulated looking time measure did not distinguish between the two, showing an increase for both. Thus, social looking is a more valid measure of infant VoE than looking time.

Perception of occlusion by young infants: Must the occlusion event be congruent with the occluder?

Four-month-old infants perceive continuity of an object's trajectory through occlusion, even when the occluder is illusory, and several cues are apparently needed for young infants to perceive a veridical occlusion event. In this paper we investigated the effects of dislocating the spatial relation between the occlusion events and the visible edges of the occluder. In two experiments testing 60 participants, we demonstrated that 4-month-olds do not perceive continuity of an object's trajectory across an occlusion if the deletion and accretion events are spatially displaced relative to the occluder edges (Experiment 1) or if deletion and accretion occur along a linear boundary that is incorrectly oriented relative to the occluder's edges (Experiment 2). Thus congruence of these cues is apparently important for perception of veridical occlusion. These results are discussed in relation to an account of the development of perception of occlusion and object persistence.

In infancy the timing of emergence of the other-race effect is dependent on face gender.

Poorer recognition of other-race faces relative to own-race faces is well documented from late infancy to adulthood. Research has revealed an increase in the other-race effect (ORE) during the first year of life, but there is some disagreement regarding the age at which it emerges. Using cropped faces to eliminate discrimination based on external features, visual paired comparison and spontaneous visual preference measures were used to investigate the relationship between ORE and face gender at 3-4 and 8-9 months. Caucasian-White 3- to 4-month-olds' discrimination of Chinese, Malay, and Caucasian-White faces showed an own-race advantage for female faces alone whereas at 8-9 months the own-race advantage was general across gender. This developmental effect is accompanied by a preference for female over male faces at 4 months and no gender preference at 9 months. The pattern of recognition advantage and preference suggests that there is a shift from a female-based own-race recognition advantage to a general own-race recognition advantage, in keeping with a visual and social experience-based account of ORE.

Trajectory perception and object continuity: effects of shape and color change on 4-month-olds' perception of object identity.

Previous work has demonstrated that infants use object trajectory continuity as a cue to the constant identity of an object, but results are equivocal regarding the role of object features, with some work suggesting that a change in the appearance of an object does not cue a change in identity. In an experiment involving 72 participants, we investigated the effects of changing object shape and color, singly and in combination, on 4-month-olds' perception of object continuity. A change in the shape of an object while it passed behind an occluder had no effect on perception of continuity, whereas a change in shape and color led to perception of discontinuity, and a change in color led to no clear percept regarding continuity or discontinuity. These results are discussed in terms of a perceptual learning model of development of object identity.

The effects of auditory information on 4-month-old infants' perception of trajectory continuity.

Young infants perceive an object's trajectory as continuous across occlusion provided the temporal or spatial gap in perception is small. In 3 experiments involving 72 participants the authors investigated the effects of different forms of auditory information on 4-month-olds' perception of trajectory continuity. Provision of dynamic auditory information about the object's trajectory enhanced perception of trajectory continuity. However, a smaller positive effect was also obtained when the sound was continuous but provided no information about the object's location. Finally, providing discontinuous auditory information or auditory information that was dislocated relative to vision had negative effects on trajectory perception. These results are discussed relative to the intersensory redundancy hypothesis and emphasize the need to take an intersensory approach to infant perception.

Illusory contour figures are perceived as occluding contours by 4-month-old infants.

Although 4-month-olds perceive continuity of an object's trajectory through occlusion, little is known about the information specifying an occluding surface at this age. We investigated this in 3 experiments involving 84 participants. Testing the claim that 5-month-olds are unable to perceive the Kanizsa figure as an occluding surface (Csibra, 2001), we demonstrated that 4-month-olds perceived trajectory continuity behind this figure providing its horizontal extent was small. We demonstrated that the presence of visible occluding edges or occlusion of background was insufficient to specify an occluding surface but that their combination was sufficient. Thus, beyond object deletion and accretion, both visible occluding edges and occlusion of background are necessary for perception of occluding surfaces at this age.

The contribution of visual and vestibular information to spatial orientation by 6- to 14-month-old infants and adults.

Although there is much research on infants' ability to orient in space, little is known regarding the information they use to do so. This research uses a rotating room to evaluate the relative contribution of visual and vestibular information to location of a target following bodily rotation. Adults responded precisely on the basis of visual flow information. Seven-month-olds responded mostly on the basis of visual flow, whereas 9-month-olds responded mostly on the basis of vestibular information, and 12-month-olds responded mostly on the basis of visual information. Unlike adults, infants of all ages showed partial influence by both modalities. Additionally, 7-month-olds were capable of using vestibular information when there was no visual information for movement or stability, and 9-month-olds still relied on vestibular information when visual information was enhanced. These results are discussed in the context of neuroscientific evidence regarding visual-vestibular interaction, and in relation to possible changes in reliance on visual and vestibular information following acquisition of locomotion.

Two- to eight-month-old infants' perception of dynamic auditory-visual spatial colocation.

From birth, infants detect associations between the locations of static visual objects and sounds they emit, but there is limited evidence regarding their sensitivity to the dynamic equivalent when a sound-emitting object moves. In 4 experiments involving thirty-six 2-month-olds, forty-eight 5-month-olds, and forty-eight 8-month-olds, we investigated infants' ability to process this form of spatial colocation. Whereas there was no evidence of spontaneous sensitivity, all age groups detected a dynamic colocation during habituation and looked longer at test trials in which sound and sight were dislocated. Only 2-month-olds showed clear sensitivity to the dislocation relation, although 8-month-olds did so following additional habituation. These results are discussed relative to the intersensory redundancy hypothesis and work suggesting increasing specificity in processing with age.

The role of perceptual and cognitive processes in addition-subtraction studies with 5-month-old infants.

After a brief familiarization period to either one or two toys 5-month-olds gave a clear preference for perceptually novel displays, suggesting that replicable findings of greater looking at an unexpected arithmetic outcome in addition/subtraction experiments cannot easily be attributed to simple familiarity preferences.

Preverbal infants' sensitivity to synaesthetic cross-modality correspondences.

Stimulation of one sensory modality can induce perceptual experiences in another modality that reflect synaesthetic correspondences among different dimensions of sensory experience. In visual-hearing synaesthesia, for example, higher pitched sounds induce visual images that are brighter, smaller, higher in space, and sharper than those induced by lower pitched sounds. Claims that neonatal perception is synaesthetic imply that such correspondences are an unlearned aspect of perception. To date, the youngest children in whom such correspondences have been confirmed with any certainty were 2- to 3-year-olds. We examined preferential looking to assess 3- to 4-month-old preverbal infants' sensitivity to the correspondences linking auditory pitch to visuospatial height and visual sharpness. The infants looked longer at a changing visual display when this was accompanied by a sound whose changing pitch was congruent, rather than incongruent, with these correspondences. This is the strongest indication to date that synaesthetic cross-modality correspondences are an unlearned aspect of perception.

Conditions for young infants' failure to perceive trajectory continuity.

When viewing an event in which an object moves behind an occluder on part of its trajectory, 4-month-old infants perceive the trajectory as continuous only when time or distance out of sight is short. Little is known, however, about the conditions under which young infants perceive trajectories to be discontinuous. In the present studies we focus first on infants' perception of trajectories that change during a period of occlusion. Four-month-olds perceive discontinuity in trajectories that change in height or orientation while behind an occluder, and this is true even when a change in direction could be due to an invisible bouncing collision with a surface. Further experiments reveal that infants do not perceive diagonal linear trajectories as continuous across an occlusion unless the occluding and revealing edges are orthogonal to the path of movement. Implications for theories of perceptual and cognitive development are discussed.