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Perceptual Development

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					                    Perceptual
                   Development
I.    Introduction
      A. What is the infant’s phenomenological world
           like?
      B. How can we answer this question?
II.   Infant methodologies
      A. Localization techniques
          1. The orienting response
          2. Visual localization
          3. Auditory localization
      B. Habituation/Dishabituation techniques
          1. General habituation procedures
          2. The fixed trials version
          3. The infant-control procedure
          4. Dependent measures of habituation
              a. Cardiac deceleration
              b. Visual fixation
              c. Non-nutritive sucking
      C. Operant condition procedures
      D. Preference techniques
III. Research in perceptual development
     A. Categories of infant capabilities
        1. Sensory development
        2. The perception of complex stimuli
        3. Representational information
     B. Depth perception – Albert Yonas
        1. Kinetic information – complex
        2. Binocular information – sensory
        3. Pictorial cues – representational
                   Perceptual
                  Development
Basic question:
  • What does the infant’s phenomenological consist
     of?
  • What does the infant perceive and how is it
     organized
  • Different types of question can be posed
      • Visual acuity
      • Color perception
      • Auditory localization
      • Perception of objects
      • Intermodal perception
Behaviors that allow for doing research with infants:
  • Engage in exploratory behavior
  • Preference for novel stimuli
                   Localization
                   Techniques
The orienting response
  • Present infants with a stimulus
  • Measure their exploratory behavior towards the
    stimulus
  • Can include body turning, head turning, eye gaze
Visual localization
   • Present a visual target
   • Look to see if they try to fixate the target
   • Findings using localization technique
Auditory localization
  • Present an auditory target
  • Look to see if they try to fixate the target
  • Findings using localization technique
Habituation/Dishabitiuation Technique
               General Procedure


           Habituation Stimulus




      Dishabituation or Test Stimuli

      Test 1                  Test 2
Habituation/Dishabituation Technique
 Fixed-trials version:
    • Present infant with a preset number of exposures
      to the stimulus
       • Example: show stimulus 10 times, for 30 sec
          each
    • Then present test stimuli for set number of
      exposures
    • Problems with procedure
 Infant control version:
    • Present stimulus and measure attention
    • When infant stops attending for set time, take
      stimulus away – 1 trial
    • Repeat procedure until attention drops below a
      preset criterion
    • Then present test stimuli for present number of
      exposures
    • Problems with procedure
 Measures of infant attention
   • Cardiac deceleration
      • The mean number of heart beats per minute
      • Slowing down means increased attention
   • Visual fixation
      • The amount of time looking at a visual stimulus
      • Increased looking time means increased
        attention
   • Non-nutritive sucking
 Operant Conditioning Technique
Train infant to show a response to a stimulus:
   • Example:
      • Show stimulus A
      • Reinforce infants’ turning their head to look at
         a target
   • Test generalization of response by presenting a
     new stimulus
      • Show stimulus B
      • Look at whether infant makes trained response
         to new stimulus
   • The number of times infant makes a response to
     the new stimulus is a measure of the perceptual
     similarity between the two
      • If stimuli perceived as the same, response
         generalizes to new stimulus
      • If different, do not show trained response
  Preferential Looking Technique
Present two stimuli:
   • Typically simultaneously, sometimes sequentially
   • Measure differences in attention to two different
     stimuli
   • Sometimes proceeded by a familiarization phase
   • Difference in attention between the two stimuli
     indicates perceived differences

Use in intermodal perception studies:
  • Present single stimulus in one modality (auditory
     or tactile)
  • Present two stimuli in second modality (visual)
  • Look to see if infants preferentially fixate as a
     function of the nature of the single stimulus
      • Preference for an intermodal match versus
         mismatch
      • Reinforce infants’ turning their head to look at
         a target

Violation of Expectation paradigm:
   • Present two visual stimuli
       • Expected (natural, familiar)
       • Unexpected (unnatural, novel)
   • See preferential fixation of unexpected stimulus
   • Indicates knowledge of basis by which unexpected
     stimulus is unusual or unexpected
   Sensory Development

              Visual acuity
Square Wave Grating       Grey Field
Perception of Complex Stimuli

    Partly-occluded objects
    Kellman & Spelke (1983)

            Habituation Stimulus




   Test 1                     Test 2
 Depth Perception (Albert Yonas)
Kinetic information (Complex stimuli):
   • Looming
   • Accretion and deletion patterns
   • Perceived at birth (or shortly thereafter)
Binocular information (Sensory):
   • Binocular disparity
   • Convergence information
   • Perceived between 3 and 5 months
Pictorial Depth Cues (Representational information):
   • Cues used to represent depth in paintings
   • Familiar size, relative depth, linear perspective,
     interposition
   • Perceived by 7 months
Pictorial Depth Information

     Interposition Stimulus




      Control Stimulus

				
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