Four themes from 20 years of research on infant perception and cognition

This paper reviews progress over the past 20 years in four areas of research on infant perception and cognition. Work on perception of dynamic events has identified perceptual constraints on perception of object unity and object trajectory continuity that have led to a perceptual account of early development that supplements Nativist accounts. Work on face processing has charted developmental changes that clarify the way innate systems are modified by experience. Research on perception of goal‐directed action and animacy has made significant progress in uncovering the roots of social cognition from 6 months onwards. New methods such as eye tracking and measures of brain activity have done much to confirm and clarify conclusions arising from more conventional looking preference methods. It is likely that future progress in theory and understanding will be made increasingly as a result of triangulation between data arising from conventional and newer methods. Copyright © 2011 John Wiley & Sons, Ltd.     

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.     

Spatial localization of touch in the first year of life: early influence of a visual spatial code and the development of remapping across changes in limb position

Two experiments investigated infants' ability to localize tactile sensations in peripersonal space. Infants aged 10 months (Experiment 1) and 6.5 months (Experiment 2) were presented with vibrotactile stimuli unpredictably to either hand while they adopted either a crossed- or uncrossed-hands posture. At 6.5 months, infants' responses were predominantly manual, whereas at 10 months, visual orienting behavior was more evident. Analyses of the direction of the responses indicated that (a) both age groups were able to locate tactile stimuli, (b) the ability to remap visual and manual responses to tactile stimuli across postural changes develops between 6.5 and 10 months of age, and (c) the 6.5-month-olds were biased to respond manually in the direction appropriate to the more familiar uncrossed-hands posture across both postures. The authors argue that there is an early visual influence on tactile spatial perception and suggest that the ability to remap visual and manual directional responses across changes in posture develops between 6.5 and 10 months, most likely because of the experience of crossing the midline gained during this period.     

Incorporating the size principle into an ensemble of back-propagating neurons

As researchers try to move from cybernetics to neural reality, it is time to look at the match between the back propagation strategy and the functional parameters of neurons. Traditionally, the “bias value” in the back propagation activation function has served a mathematical rather than a biological function. By incorporating a production system into the activation logic at the hidden layer, we are able to arrive at a conditional bias value that approximates the function of thresholds in biological neurons.     

Using three-dimensional graphics in neuropsychological hypothesis testing

This paper presents the application of an overlapping sampling technique used with a fast Fourier transform on electroencephalographic data. The use of this sampling and analysis technique is demonstrated on data in which steady state, rate of change, and critical event hypotheses are tested. The benefit of applying computer-generated three-dimensional graphics to the results of using this innovative sampling and analysis technique is emphasized.     

A parallel but not necessarily connectionist model of the auditory system

The basic processing elements (the neurons) in the brain operate in the millisecond range and are about a million times slower than a computer (Feldman, 1985). In order to make up for this lack of computational speed, the brain must use a parallel multisynaptic method to transmit information. This paper presents a parallel processing model of the auditory system; the model accounts for the frequency and the sound-localization information.     

Component analysis of ECG by computer

The present paper describes a set of interactive computer programs and methods (i.e., cardiac component analysis, CCA) that allow the collection, summation, and averaging of the time durations of the various ECG components. The programs are written in FORTRAN and run on a Texas Instruments minicomputer using an Intecolor 8001 terminal as the display device. The program’s features include analog-to-digital conversion, color display of individual heart-beats, operator interaction, and statistical summation with tabular output. Subroutines are well structured and easily transported to other machines. Although these programs may be used on-line, it has been more efficient to perform the analyses off-line, after a subject has completed the task. Various versions of the program have been used to analyze human, baboon, and dog ECGs in 2- to 30-sec epochs, at sample rates of 258 and 1,000 samples/sec. Preliminary results from an experiment of the effects of meditation and cognitive overload are discussed.     

Form perception at birth: Cohen and Younger (1984) revisited

Cohen (1988; Cohen & Younger, 1984) has suggested that there is a shift in the perception of form sometime after 6 weeks of age. Prior to this age infants can remember the specific orientations of line segments, but cannot process and remember the angular relations that line segments can make. Experiment 1 used simple line stimuli with newborn infants to test this suggestion. Following habituation to a simple two-line angle the newborns dishabituated to a change of orientation but not to a change in angle, confirming Cohen and Younger's suggestion that orientation is a powerful cue in early shape perception. In Experiments 2 and 3 newborns were familiarized either to an acute or to an obtuse angle that changed its orientation over trials. On subsequent test trials the babies gave strong novelty preferences to a different angle. Alternative interpretations of the results are discussed, but these experimental findings are compatible with the suggestion that newborns can quickly learn to process angular relations, and that rudimentary form perception may not be dependent on a lengthy period of learning and/or maturation for its development.     

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.