Infants' intermodal perception of events

Four-month-old infants viewed two sound motion picture films of simple, natural events. The films were projected side by side, as one of the two sound tracks was played through a centrally placed speaker. Infants' visual attention to the films was consistently influenced by what they heard: They looked primarily at the event specified by the sound track. The experiment demonstrates that infants are able to perceive relations between sights and sounds in the absence of spatial cues. They respond to a perceived intermodal invariance with increased attention to the event reaching them over two modalities.     

Infants' perception of multiple-group auditory patterns

Six- and 12-month-old infants were tested for their perception of a variety of features of multiple-group auditory patterns. Each pattern comprised nine pure tones organized as three groupings each of three elements. The features examined included: (1) features having to do with frequency composition, designated as “local” pattern features; and (2) features involving relations between pattern components, designated as “global” pattern features. Infants were tested with a Go/No-Go conditioned head-turn procedure. Twelve-month-olds readily performed all discriminations. By contrast, 6-month-olds had greater difficulty discriminating local than global pattern features and showed limitations in their ability to organize three distinct groupings of elements into a unified pattern. Results are discussed with reference to infants' perception of features of single-group patterns and the notion of developmental changes in auditory information-processing capacities.     

Infants' perception of pictorially specified interposition

Five- and seven-month-olds were tested for sensitivity to pictorial interposition in two experiments. Reaching was used as the dependent measure. Seven-month-olds gave evidence of sensitivity to pictorial interposition. In both experiments they showed a significant preference to reach for the pictorially nearer side of a flat interposition display which stimulated three overlapping surfaces and showed no reaching preferences when viewing control displays. Five-month-olds' reaching tendencies did not differ significantly between experimental (interposition) and control conditions in the second experiment. This result indicated that their responses may have been due to nonspatial proximal stimulus variables in the displays. Five-month-olds, therefore, gave no evidence of sensitivity to pictorial interposition. The finding that 7-month-olds are sensitive to pictorial interposition and the failure to find sensitivity in 5-month-olds is consistent with findings from other studies on infants' sensitivity to pictorial depth information. The cumulative results of these studies suggest that sensitivity to pictorial depth information first appears between 5 and 7 months of age.     

Stimulation and perception of transparency

Summary After a brief exposition of the algebraic theory of transparency and of the various experimental predictions deduced from it, the theory is reconsidered with reference to the paradigmatic case of transparency obtained using an episcotister. The first result of this analysis is that the same local stimulation, described by the same equation, gives rise either to color fusion or to color scission, that is, to transparency. Therefore, the assertion that the same equations (Talbot's law) describe both the color fusion and transparency is not a hypothesis but the ascertaining of a fact. Another important result is that the two parameters of transparency, the coefficient of transparency and the measure of the color t of the transparent layer, correspond to the empty sector of the episcotister and to the color of the episcotister, respectively, both being therefore physical measures.     

Infants' perception of depth from cast shadows

Five- and 7-month-old infants viewed displays in which cast shadows provided information that two objects were at different distances. The 7-month-olds reached preferentially for the apparently nearer object under monocular-viewing conditions but exhibited no reaching preference under binocular-viewing conditions. These results indicate that 7-month-old infants perceive depth on the basis of cast shadows. The 5-month-olds did not reach preferentially for the apparently nearer object and, therefore, exhibited no evidence of sensitivity to cast shadows as depth information. In a second experiment, 5-month-olds reached preferentially for the nearer of two objects that were similar to those used in the first experiment but were positioned at different distances from the infant. This result indicated that 5-month-olds have the motor skills and motivation necessary to exhibit a reaching preference under the conditions of this study. The results are consistent with the hypothesis that depth perception based on cast shadows first appears between 5 and 7 months of age.     

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' perception of subjective contours from apparent motion

We examined infants' perception of subjective contours in Subjective-Contour-from-Apparent-Motion (SCAM) stimuli [e.g., Cicerone, C. M., Hoffman, D. D., Gowdy, P. D., & Kim, J. S. (1995). The perception of color from motion. Perception & Psychophysics, 57, 761-777] using the preferential looking technique. The SCAM stimulus is composed of random dots which are assigned two different colors. Circular region assigned one color moved apparently, keeping all dots' location unchanged. In the SCAM stimulus, adults can perceive subjective color spreading and subjective contours in apparent motion (http://c-faculty.chuo-u.ac.jp/ approximately ymasa/okamura/ibd_demo.html). In the present study, we conducted two experiments by using this type of SCAM stimulus. A total of thirty-six 3-8-month-olds participated. In experiment 1, we presented two stimuli to the infants side by side: a SCAM stimulus consisting of different luminance, and a non-SCAM stimulus consisting of isoluminance dots. The results indicated that the 5-8-month-olds showed preference for the SCAM stimuli. In experiments 2 and 3, we confirmed that the infants' preference for the SCAM stimulus was not generated by the local difference and local change made by luminance of dots but by the subjective contours. These results suggest that 5-8-month-olds were able to perceive subjective contours in the SCAM stimuli.     

Infants' perception of concavity and convexity of shaded objects

The discriminative sensitivities of 30 4‐month‐old and 30 8‐month‐old infants for concave and convex objects were measured using the preferential‐looking method. Five cylinder‐like objects with different magnitudes of concave or convex shaded surfaces and outline contours were presented to the infants in pairs. The results indicated that the 4‐month‐old infants could discriminate better between object convexities than between object concavities. In contrast, the 8‐month‐old infants were able to equally discriminate between object concavities and object convexities, and their sensitivity to both object concavity/convexity was much higher than that of the 4‐month‐old infants. This difference in the sensitivity to object concavity and convexity suggested that younger and older infants might have differential abilities for cue utilization for recovering object structures.     

Infants' haptic perception of object unity in rotating displays

Four-month-old infants were allowed to manipulate, without vision, two rings attached to a bar that permitted each ring to undergo rotary motion against a fixed surface. In different conditions, the relative motions of the rings were rigid, independent, or opposite, and they circled either the same fixed point outside the zone of manipulation or spatially separated points. Infants' perception of the ring assemblies were affected by the nature of the rotary motion in two ways. First, infants perceived a unitary object when the felt ends of the object underwent a common, rigid rotary motion; perception of object unity was stronger in this condition than when the ends underwent either independent or opposite rotary motions. Second, infants perceived two distinct objects when the felt ends of the objects underwent independent rotary motions that centred on distinct fixed points. Perception of the distinctness of the objects was less clear when the ends underwent opposite or independent rotary motions that centred on a common fixed point. These findings provide the first evidence that infants are sensitive to rotary motion patterns and can extrapolate a global pattern of rigid motion from the distinct, local velocities that they produce and experience at their two hands.     

Infant perception of static two-dimensional transparency information

The present habituation – dishabituation study focused on infants' perception of static two-dimensional transparency displays. Infants 4 and 8 months of age were habituated to a transparency display. In this stimulus, each corner of a semi-transparent square surface covered a quadrant of a circle. During the posthabituation period, the infants were presented with the semi-transparent square overlay from the habituation display and a (non-transparent) square area cut out of the habituation stimulus. The 8-month-olds looked significantly longer at the non-transparent surface, meaning that they apparently recognized the other test pattern as the semi-transparent filter they had also seen during the habituation trials, and that they regarded the non-transparent test target as being novel. In contrast, the younger participants did not exhibit a novelty preference during the posthabituation trials. Control conditions tested the impact of spontaneous stimulus preferences on the results. The findings are discussed within the framework of infant pictorial depth perception. They provide further evidence for the hypothesis that infants' sensitivity to pictorial depth cues emerges between 4 – 5 and 7 – 8 months of life.     

Infants' distance perception from linear perspective and texture gradients

This study investigated 5- and 7-month-old infants' abilities to perceive objects' distances from pictorial depth cues, the depth cues available to a stationary, monocular viewer. Infants viewed a display in which texture gradients and linear perspective, two pictorial depth cues, created an illusion of two objects resting at different distances on a textured surface. Under monocular viewing conditions, 7-month-olds reached preferentially for the apparently nearer object, indicating that they perceived the objects' relative distances specified by pictorial depth cues. Under binocular viewing conditions, these infants showed no reaching preference. This finding rules out interpretations of the results not based on the objects' perceived distances. The 5-month-olds' reaching preferences were not significantly different in the experimental (monocular) and control (binocular) conditions. These infants, therefore, did not show clear evidence of distance perception from pictorial depth cues.     

Infants' perception of illusory contours in static and moving figures

We investigated 3-8-month-olds' (N=62) perception of illusory contours in a Kanizsa figure by using a preferential looking technique. Previous studies suggest that this ability develops around 8 months of age. However, we hypothesized that even 3-4-month-olds could perceive illusory contours in a moving figure. To check our hypothesis, we created an illusory contour figure in which the illusory square underwent lateral movement. By rotating the elements of this figure, we created non-illusory contour figures. We found that: (1) infants preferred moving illusory contours to non-illusory contours by 3-4 months of age, and (2) only 7-8-month-olds preferred static illusory contours. Our findings demonstrate that motion information promotes infants' perception of illusory contours. Our results parallel those reported in the study of partly occluded objects ().     

Infants' perception of goal-directed actions: development through cue-based bootstrapping

It is now widely accepted that sensitivity to goal-directed actions emerges during the first year of life. However, controversy still surrounds the question of how this sensitivity emerges and develops. One set of views emphasizes the role of observing behavioral cues, while another emphasizes the role of experience with producing own action. In a series of four experiments we contrast these two views. In Experiment 1, it was shown that infants as young as 6 months old can interpret an unfamiliar human action as goal-directed when the action involves equifinal variations. Experiments 2 and 3 demonstrated that 12- and 9-month-olds are also able to attribute goals to an inanimate action if it displays behavioral cues such as self-propelledness and an action-effect. In Experiment 4, we found that even 6-months-olds can encode the goal object of an inanimate action if all three cues, equifinality, self-propelledness and an action-effect, were present. These findings suggest that the ability to ascribe goal-directedness does not necessarily emerge from hands-on experience with particular actions and that it is independent from the specific appearance of the actor as long as sufficient behavioral cues are available. We propose a cue-based bootstrapping model in which an initial sensitivity to behavioral cues leads to learning about further cues. The further cues in turn inform about different kinds of goal-directed agents and about different types of actions. By uniting an innate base with a learning process, cue-based bootstrapping can help reconcile divergent views on the emergence of infants' ability to understand actions as goal-directed.     

Infants' perception of goal‐directed actions on video

Imitation studies and object search studies show that infants have difficulties using action information presented on video to guide their own behaviour. The present study investigated whether infants also have problems interpreting information shown on video relative to real live information. It was examined whether 6‐month‐olds interpret an action with a salient action effect as goal‐directed when it is performed by an actor on a video‐screen and when it is performed by a live actor. A video presentation of a goal‐directed action display was presented to one group of infants, and another group received the same action display, matched in all details, live on a stage. Results indicate that 6‐month‐olds in the video group as well as in the live group interpreted the human action as goal‐directed. Moreover, comparison across both groups revealed no difference in the overall looking pattern between the video and the live presentation group. Thus, our findings show that infants as young as 6 months of age can take important information from video clips and interpret televised actions in meaningful ways that is equivalent to their interpretation of live actions.     

Infants' perception of information along object boundaries: concavities versus convexities

Object parts are signaled by concave discontinuities in shape contours. In seven experiments, we examined whether 5- and 6 1/2-month-olds are sensitive to concavities as special aspects of contours. Infants of both ages detected discrepant concave elements amid convex distractors but failed to discriminate convex elements among concave distractors. This discrimination asymmetry is analogous to the finding that concave targets among convex distractors pop out for adults, whereas convex targets among concave distractors do not. Thus, during infancy, as during adulthood, concavities appear to be salient regions of shape contours. The current study also found that infants' detection of concavity is impaired if the contours that define concavity and convexity are not part of closed shapes. Thus, for infants, as for adults, concavities and convexities are defined more readily in the contours of closed shapes. Taken together, the results suggest that some basic aspects of part perception from shape contours are available by at least 5 months of age.