Transcript Perceptual Development

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
• Sucking pressure on a stimulus
• Changes in sucking pressure indicate changes in
attention
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