HUMAN DEVELOPMENT 1 PSYCHOLOGY 3050: Infant Perception 1 Ch 7

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HUMAN DEVELOPMENT 1PSYCHOLOGY 3050Infant
Perception 1 (Ch 7)
Dr. Jamie Drover SN-3094, 737-8383 e-mail
jrdrover_at_mun.ca Winter Semester, 2009
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Infant Perception

• Most of what we think about consists of objects,
  words, or messages that were received through the
  senses.
• Infants play an active role in their own
  perception.
• Infants learn through their perceptions.

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Basic Perceptual Abilities of Young Infants

• It was once thought that infants were born deaf
  and blind.
• Although far from mature, all of the infants
  senses are functioning.
• They even prefer some sights, smell, and sounds
  over others.
• Vision and hearing develop rapidly over the first
  year.
• As newborns, infants are also sensitive to pain
  and touch.

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Basic Perceptual Abilities of Young Infants

• The chemical senses (taste and smell) develop
  early.
• Six-day olds prefer the scent of their mothers
  breast pads over those of a stranger.

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Methodologies of Infant Perception

• To assess infant perception, we must observe a
  behavior that an infant can control and use that
  to infer perception.
• Sucking Response
• Researchers often use infants sucking rates.
• DeCasper and Spence (1986) had pregnant women
  read one of three passages aloud twice per day.

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Methodologies of Infant Perception

• Shortly after birth, headphones were placed on
  the infants.
• One of several passages could be played over the
  headphones based on sucking rates.
• Infants would alter their sucking rates in order
  to hear the reading of familiar passages.

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Methodologies of Infant Perception

• Visual Preference Paradigm
• Fantz (1958, 1961) placed babies in a looking
  chamber and presented them several visual
  stimuli.
• If they spend more time gazing at one pattern
  more than another, it is assumed they can
  discriminate between them.

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Habituation/Dishabituation

• Habituation the decrease in response to a
  stimulus as a result of repeated presentations of
  that stimulus.
• Infants can habituate to a visual stimulus.
• The longer infants are exposed to a stimulus, the
  less time they will spend looking at it.
• Habituation occurs when there is a substantial
  decrease in looking time following repeated
  presentation.

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Habituation/Dishabituation

• Often defined as when fixation to the stimulus is
  50 of what it was initially.
• If a new stimulus is then presented, the infant
  may show a sudden increase in looking time.
• This is dishabituation.
• Thus, the infant can discriminate between the two
  stimuli.
• Also indicates that infants can remember the
  earlier stimulus.

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Habituation/Dishabituation
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Habituation/Dishabituation

• Using this paradigm, Friedman (1972) found
  evidence that 1- to 3-day-old infants will
  habituate and dishabituate to visual stimuli.
• Newborns are capable of visual memory.

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Auditory Development

• The primary means of human communication involves
  audition.
• Auditory perception is well-developed in the
  newborns, particularly at high frequencies.
• DeCasper and Fifer (1980) found that 1- to
  3-day-old infants will alter their sucking rates
  to hear a tape recording of their mothers as
  opposed to that of a stranger.

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Auditory Development

• DeCasper and Spence (1986) earlier research shows
  on infants and sucking rate show that theyre
  capable of auditory learning prenatally.
• Studies measuring heart rate in response to
  familiar and novel passages during the third
  trimester reveals similar findings.

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Last Class

• Deception
• Chandler et al. (1989) withhold evidence,
  destroy evidence, lying, produce false evidence.
• Four modules for mindreading,
• Intentionality Detector, Eye Direction Detector,
  Shared Attention Mechanism, Theory of mind
• Autism, Down Syndrome
• Basic Perceptual abilities
• All senses are functioning at birth
• Methodologies
• Sucking Response (DeCasper Spence, 1986)
• Visual Preference Paradigm
• Habituation/Dishabituation

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Last Class

• Auditory Development
• DeCasper Fifer (1980)

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Speech Perception

• Infants can perceive most and perhaps all
  phonemes found in all human languages.
• Phonemes the basic units of speech.
• Eimas et al. (1971) repeatedly presented
  1-month-olds with a phoneme along the ba/pa
  continuum until they showed a decrease in sucking
  rate (i.e., habituation).

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Speech Perception

• Infants would show an increase in sucking rate
  (dishabituate) if a phoneme was presented on the
  other side of the ba/pa continuum.
• They use the same dividing line as older children
  and adults.
• Marean, Lynne, and Kuhl (1992) found when using
  reinforcement, that infants will turn their heads
  when a vowel sound changes are made.
• A to I

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Speech Perception

• Infants can make phoneme discriminations that
  adults can not make.
• They can make discriminations in foreign
  languages that adults can not make.
• However, this ability is quickly lost.
• This language flexibility is probably not
  adaptive after a certain age.
• The brain should dedicate neurons to processing
  sounds in the language its exposed to.

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Speech Perception

• Infants are able to recognize frequently heard
  sound patterns at least by 4.5 months of age.

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The Development of Visual Perception

• Infants can perceive light (pupillary reflex) but
  because of poor accommodation, much of what they
  see is blurry.
• Accommodation is adult-like at 3 months.
• Newborns can track a moving object, but the eyes
  do not always move in harmony.
• Visual acuity of newborns is 20/600 to 20/400.

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Testing Infants Visual Acuity

• Can be done using forced choice preferential
  looking.
• Infants are presented with rectangular cards that
  contain black and white stripes on one side of a
  central peephole, while the other side is blank.
• Teller Acuity Cards
• Given an infants preference for patterned
  stimuli over unpatterned stimuli, if he/she can
  detect the stimulus, he/she will fixate it.

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Testing Infants Visual Acuity

• A naïve observer must determine the location of
  the stripes based on the fixation of the child.
• The thinnest stripewidth at which the observer
  can determine the location of the stripes
  provides a measure of visual acuity.

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The Development of Visual Perception

• Vision is poor at birth because the fovea is
  underdeveloped.
• Point on the retina where vision is sharpest.
  Packed with cones.
• The infant fovea contains large, less densely
  packed cones.
• Newborns can discriminate between red and white,
  but can not differentiate blue, green, and yellow
  from white (Adams et al.1994).

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Primary and Secondary Visual Systems

• Bronson (1974) believed that vision in the 1st
  month is governed by the secondary visual system
• Mediates visually guided behavior.
• Under the control of subcortical structures.
• Deals with peripheral vision.
• Tells us where something is.

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Primary and Secondary Visual Systems

• The primary visual system influences vision
  beginning at about 2 months of age.
• Under the influence of the fovea.
• Infants now start to analyze a stimulus.
• Provides information on what a stimulus is.
• This shift is not as abrupt as Bronson thought.

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The Development of Visual Preferences

• Until 2 months of age, an infants visual
  preferences are affected by physical properties
  of the stimulus.
• Babies prefer moving stimuli over stationary
  stimuli.
• See Haith (1966) p. 193.
• Infants prefer high contrast stimuli over low
  contrast stimuli.
• See Salapatek and Kessen (1966) p. 193.

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The Development of Visual Preferences
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The Development of Visual Preferences

• Infants at 1 month of age focus their attention
  primarily on the outside of a figure.
• Externality effect.

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The Development of Visual Preferences

• At 4 months, infants start to show a preference
  for vertical symmetry.
• They prefer to process stimuli that are vertical
  and symmetrical as opposed to asymmetrical and
  horizontal stimuli.

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Attention to the Human Face

• Infants prefer vertical, symmetrical stimuli with
  curved lines making them well-suited to attend to
  faces.
• A bias to human faces would make evolutionary
  sense and would facilitate attachment.
• Johnson et al. (1991) showed newborns paddle
  stimuli which resembled faces, did not resemble
  faces, or were blank.

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Attention to the Human Face

• They presented these stimuli and moved them.
• Measured how much infants followed the stimuli by
  moving their eyes and head.
• Following this paradigm, infants will show a
  preference for face like stimuli as early as 5
  days of age.

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Attention to the Human Face

• There is evidence that newborns may be able to
  make discriminations between faces.
• Look longer at their mothers than other women.
• The will alter sucking rate to see a photo of
  their mother over another woman (Bower, 1992).
• Babies also show a preference for attractive
  faces over unattractive faces (Langlois, 1987).
• Infants as young as two months will look longer
  at attractive faces as opposed to unattractive
  faces.

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Attention to the Human Face

• This might be because infants prefer upright,
  curvilinear, symmetrical stimuli.
• It might be evolutionary since symmetry is a sign
  of health.
• Important for mate selection.
• Infant also prefer to look at faces in which the
  eyes are gazing in their direction (Farroni et
  al., 2002).
• See page 197

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Psychological Stimulus Characteristics

• At around 2 to 4 months, psychological
  characteristics of a stimulus become important to
  infants.
• Eg., familiarity and novelty
• Kagan (1971) proposed that at 2 months, infants
  form schemas.
• Sensory representations of a stimulus.
• The similarity of a stimulus to a previously
  determined stimulus will determine attention.

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Psychological Stimulus Characteristics

• Infants are most attentive to stimuli that are
  moderately discrepant from a schema.
• Discrepancy principle.
• They are less attentive to stimuli that are
  highly familiar, or highly discrepant.
• But, there are situations in which infants prever
  to attend to familiar stimuli.

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Psychological Stimulus Characteristics

• Generally, young infants prefer familiar stimuli,
  then show no preference, then they prefer novel
  stimuli.
• Takes time to create schemas.