Cognitive Development

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Cognitive Development

• Outline
• Sensory systems
• Perception
• Experimental Methods
• Object Perception/permanence
• Theory of Mind
• Definition
• Developmental aspects
• False-belief test

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Cognitive Development

• Cortical Growth
• After birth, human cortex continues to develop,
  including massive increases in the number of
  synapses. In first year the number of synapses
  increase ten fold.
• Brain size, like body size, increases in spurts
  (e.g., spurts at ages 2, 6, 10, 14 are associated
  with 10 growth in size). Much of this growth is
  associated with non-neural tissue (glial cells
  and myelination).

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Cognitive Development

• Cortical Growth
• Through first two years the rate of increases in
  synaptic connections outpaces the rate of
  synaptic loss.
• After year two, pruning outpaces the
  establishment of new synaptic connections. Adult
  has about half the synaptic connections of a
  2-year old (Gleitman et al.)

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Cognitive Development

• Development of Sensory Systems
• At birth the perceptual systems are immature.
• Visual acuity appears to be nearly adult-like by
  6 months, and adult-like by 1 year.
• Auditory acuity appears to be mature by 4-6
  months of age.

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Sensory Systems
Hearing Test at birth
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Cognitive Development

• Development of Visual Perception
• Infants display preferences. For example, there
  is an early preference for high-contrast,
  low-spatial frequency objects.
• Such preferences are thought to reflect the
  developing visual system the child seeks what
  are highly visible patterns.

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Cognitive Development

• Development of Visual Perception
• Faces
• by several weeks of age many infants show
  preferences for faces
• Also evidence of preference for mothers face
  (post-birth learning).
• Perhaps due to high visibility of faces? (when
  mothers wear scarves no longer preferred face)
• By 3 months of age babies --
• Prefer looking at faces then other complex
  patterns
• Prefer looking at mothers/familiar face

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Cognitive Development

• Development of Visual Perception Experimental
  methods.
• How to test an infants ability so see an
  object, its ability to represent the object,
  etc.
• Consider 2-month old infants, how does a 2-month
  make responses in experiments?
• Not speak, not point, not press buttons, etc.
• Yes control eyes, yes nurse (suck), yes have
  active brains, yes have changes in heart rate.

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Cognitive Development
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Cognitive Development

• Experimental methods Simple Preference
• Parent holds child (parent does not view scene).
• Two figures are presented.
• The child will often prefer one over the other
  as indicated by amount of time looking at the
  picture.
• This indicates (a) the child can discriminate
  between the figures, and (b) has a disposition to
  attend to one figure over another.

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Cognitive Development

• Experimental methods Habituation
• Assume discrimination of sounds. Parent holds
  child and wears headphones
• A sound is repeated over and over. The child
  will loose interest (habituation).
• A change in sound is introduced. The child will
  re-gain interest (dishabituation) provided the
  child can discern the change.
• The habituation/dishabituation procedure is
  repeated, and changes in interest are measured
  via
• Heart rate
• Looking time (visual stimuli)
• etc.

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Cognitive Development

• Experimental methods habituation cont.
• Habituation/Dishabituation takes advantage of
• Child has a preference for novel vs. familiar
  events
• Allows tests of
• Perceptual discrimination abilities
• Perceptual preferences
• Recognition/memory abilities

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Cognitive Development

• Habituation/dishabituation and looking time

(baby pic from Gleitman et al. adult pic from
web)
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Cognitive Development

• Experimental methods TSD.
• A more sensitive, but time-intensive method uses
  Theory of Signal Delectability (Bayes rule!) to
  examine perceptual sensitivity.
• Most useful when feedback is positive
  reinforcement
• Requires many trials!
• Consider estimate to presence of a sound
  (audibility)

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Cognitive Development

• Experimental methods TSD cont.
• Parent holds child (parent hears noise though
  headphones).
• Experimenter watches child (also masking noise).
• A detection trial occurs. The experimenter must
  indicate whether the child detected the sound.
• Feedback to experimenter and child.
• Sensitivity of the experimenter/child pair.
• The cue the experimenter uses may be any of a
  number of cues leg wiggle, etc.

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Cognitive Development

• Development of Visual Perception
• Perception of objects object permanence.
• Piaget (1896-1980) suggested when objects are no
  longer in an infants sight of view, the object
  ceases to exist there is no object permanence.
• Modest evidence cover a toy with a cloth. The
  child (6 months) watches the experimenter cover
  the toy. But, there is no effort to retrieve the
  toy. It has disappeared
• This is a critical claim that infants do not
  have a representation for the toy that exists
  sans the sensory experience of the toy.

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Cognitive Development

• Failure of Object permanence?

(pic from Gleitman et al.)
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Cognitive Development

• Visual Perception object permanence
• More recent studies
• Effect of occlusion. Consider rod-behind-block.
• More looking time to broken than continuous rod.
  (4 mos)

(pic from Gleitman et al.)
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Cognitive Development

• Visual Perception object permanence
• More recent studies
• Hidden block study. When an object is clearly
  seen, more looking time to incorrect effect of
  projected motion of occluder. Strong evidence
  for object permanence. (4 mos.)

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Cognitive Development

• Object permanence block study

(pic from Gleitman et al.)
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Cognitive Development

• Social Cognition Theory of mind
• Theory of Mind The set of interrelated concepts
  and beliefs that we employ when we try to make
  sense of our own behavior or behavior of other
  individuals
• In adults
• Know others have beliefs
• Know others beliefs may be True or False
• Others have desires, possibly different from our
  own
• Others may know things we do not, and the opposite

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Cognitive Development

• Social Cognition Toward a theory of mind
  (examples)
• Infants (9 mos) are aware that there others live
  in their world for example, follow the gaze of
  the parent (aboutness).
• 2-3 year olds will turn picture to show parent
• 3-4 year-olds can appreciate that others have
  different (visual) points of view then their own.
  
• Children are not hopelessly egocentric
  understanding of perception and vantage point of
  others

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Cognitive Development

• Social Cognition Infants understanding of the
  mind
• Two skills point to initial understanding of
  minds or at least foundational for an
  understanding of mind.
• Reciprocity with Agent Other
• Know that humans are special objects baby acts
  others react. (Agency).
• Learns to wait turns (peek-a-boo)
• Aboutness
• Early in the first year, infants understand
  people are different from objects.
• Late in first year infants learn how people
  relate to objects psychologically (aboutness
  e.g., dads behavior is about the toy if he looks
  at it).

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Cognitive Development

• Social Cognition Toddlers understanding of the
  mind
• After year 2, awareness that others have inner
  experiences empathizes with others in pain.
  Also teasing siblings.
• Emergence of language includes references to
  states (e.g., they scare me).
• However, what the words refer to is not
  necessarily the internal state implied by a 9
  year old (perhaps behaviors, internal physical
  states, aboutness).

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Cognitive Development

• Beliefs
• (age 3) Jon wants to play with Grover. Jon
  thinks Grover is on the couch. Where will Jon
  look for Grover? On the couch.
• Does this demonstrate a 3-year-old is aware
  others have beliefs and those beliefs are
  different?
• False-belief tests. Child and doll Alice see
  experimenter put candy in green box, and that
  there is no candy in the red box. Doll Alice
  leaves. Experimenter (and child) move candy from
  green to red box. Child asked Where will doll
  Alice look for the candy?. Child responds in
  the red box. (up to age 4 or so).

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Step 1
False belief test taken from M. Liberman
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Step 2
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Step 3
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Step 4
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Cognitive Development

• Theory of Mind -- Beliefs
• 3 year-olds do not realize that people have
  representations of the world that may be true or
  false and people act on the basis of those
  beliefs, not the way the world actually is. 5
  year-olds do possess such a theory of mind

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Cognitive Development

• Theory of Mind Potential models
• As toddlers develop, their theory of mind also
  develops. There are two general theories
  concerning this change
• Modularity Theory neurological maturation
  directs the theory of mind. Experience serves a
  trigger during maturation.
• Simulation Theory children use their own
  knowledge of mental states to simulate mental
  states in others. As an example in the false
  belief task children ask themselves, what would
  I think?