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Mark S. Strauss, Ph.D Home |
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Perceptual Development in Infancy Our knowledge of the world revolves around the ways we interpret sensory information Much of what we perceive is processed implicitly without our awareness Yet, is has a major impact on how we process information and ultimately who we are as humans How do we know what is music or noise Why do we see certain colors What do we find attractive
How do you know what this is? Historical Debate and Interest Consider the simple ability to perceive depth History of Nativist-Empiricist Debate DeCartes (1638): Humans are born with "natural" laws that can measure the angle of the eyes, e.g., we are built with trigonometric tables in our heads Nativist-Empiricist Debate Berkeley (1709):Argured for empiricism: Infants learn depth through feedback from their tactile and motor experiences. They associate eye movements with hand and arm movements. Touch Teaches Vision! Nativist-Empiricist Debate Immanuel Kant (1981): Mind doesn�t rely on experience for meaning but innately organizes sensations into perception Depth perception emerges too early in life to have been learned Even adults with limited experience (e.g., handicapped) experience depth Theoretical Positions Empiricists/Constructivists: All of perception is learned through active interactions in the world and cultural transmission Nativists: Perceptual Abilities are all innate James & Elinore Gibson: Perception is innate, and infants naturally perceive "affordances" or important environmental information. Gestalt Psychologist: Perception is learned except for figure/ground distinctions How to empirically study this? In the 1960�s Gibson used the visual cliff "Common sense might suggest that the child learns to recognize falling-off places by experience�that is, by falling and hurting himself. But is experience really the teacher? Or is the ability to perceive and avoid a brink part of the child�s original endowment?" The Visual Cliff Visual Cliff Research Gibson concluded: So few infants crossed the "deep" side that it must be innate Bertenthal and Campos: 2 month olds show heart rate decrease when put on the "deep" side. This suggest they can perceive depth but are not afraid Fear develops late based on parents and "social referencing" How do we perceive depth? Oculomotor Cues Accomodation and Convergence both begin at approximately two months of age and provide infants with depth information Both only provide information about close-up distances How do we perceive depth? Binocular: Retinal Disparity Binocular: Retinal Disparity Binocular: Retinal Disparity Richard Aslin: Research showing infants 3-D movies while wearing glasses Infants by 4 to 6 months perceive and use retinal disparity Probably an innate skill that shows later maturation How do we perceive depth? How do you perceive depth Texture Gradient Texture decreases with distance Relative Size Size decreases with distance and can be compared with known objects Interposition Contours of one object partially occlude another object Shading Farther away objects appear darker Pictorial or Monocular Cues Yonas & Granrud: Studies using infants reaching when objects appear at different distances because of pictorial cues Sensitivity to these cues emerge around 7 months of age Are they learned or innate? Gibson would argue they are affordances that don�t get "triggered" until this age Uniformity of development suggests this may be true Perception of Pattern or Figures How do we perceive figure vs background? What do you perceive? How do you know what is figure or ground? Gestalt School of Perception Must be innate rules to organize figure from background Perception of Complete Figures Subjective Contours Illusion: Infants perceive by 3 to 4 months What about movement? Study by Kellman & Spelke
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