Visual Perception, Attention

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Visual Perception, Attention Action
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Attention

• 1) Visual Spotlight

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Attention

• 2) Visual Short Term Memory
• For items not presently in the perceptual stream
• Capacity depends upon familiarity and item
  complexity
• Delayed match to sample
• N-back task
• Interaction of Dorsolateral Frontal System and
  Posterior Parietal System

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Attention

• 2) Visual Short Term Memory
• For items not presently in the perceptual stream
• Capacity depends upon familiarity and item
  complexity
• Delayed match to sample
• N-back task
• Interaction of Dorsolateral Frontal System and
  Posterior Parietal System

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Attention

• 2) Visual Short Term Memory
• For items not presently in the perceptual stream
• Capacity depends upon familiarity and item
  complexity
• Delayed match to sample
• N-back task
• Interaction of Dorsolateral Frontal System and
  Posterior Parietal System

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Attention

• 3) Hemi-field Neglect as an Atttention Disorder

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Eye Movements

• 1) Smooth Pursuit Eye Movement
• 2) Vergence Eye Movements
• 3) Saccades
• 4) Microsaccades
• 5) Vestibular Eye Movements

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1) Smooth Pursuit Eye Movement

• Volitional eye movements for tracking laterally
  moving objects
• Dynamic visual acuity is less than static acuity
  because of image slip.
• DUI

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2) Vergence Eye Movements

• Volitional eye movements for tracking approaching
  or receding objects
• Conjugate vs. Discongugate

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3) Saccades

• Volitional eye movements for gaze shift
• Change point of fixation
• Up to 6/sec.
• Role of motor efferents in perceptual stability
• Saccadic suppression

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4) Microsaccades

• Nonvolitional eye movements
• Prevent receptor fatigue

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5) Vestibular Eye Movements

• Nonvolitional eye movements to compensate for
  head motion
• The semicircular canals of the inner ear detect
  head position and motion
• What if vestibular information does not match
  visual information?

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Balance Posture

• Interaction of visual, proprioceptive and
  vestibular systems
• Depends heavily on vision
• Afferents from perceptual systems are processed
  very quickly to produce the correct efferents to
  the musculature

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Dynamic Balance

• Running in the dark
• Postural Sway

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Visual Control of Locomotion

• Simple Updating

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Visual Control of Locomotion

• Complex Brains Allow Complex Strategies
• Motor learning allows strategies to become
  adaptive

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Action Observation Imitation

• Neurons of macaques respond to visual recognition
  of hand actions performed by others.
• Response of these cells is dependent upon the
  interrelation of hand and object movements.
• Lack of response when the object is grasped with
  a tool.

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• Motor properties of a typical F5 motor neuron

• is active specifically during a particular
  grasping
• action phase (opening, closing, holding)

Area F5 may be considered a storage of motor
plans (vocabulary)
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Monkey See, Monkey Do

• An F5 mirror neuron fires during initial
  observation and then similarly during action
• However, it only fires during initial observation
  if the task is to be copied

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F5 Neuron While Monkey Observes Grasping
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Same Motor Neuron During Grasping
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The human mirror system fMRI

• Experimental situation
• Observation of mouth grasping vs observation of
  static mouth
• Observation of hand grasping vs observation of
  static hand
• Observation of foot pressing vs observation of
  static foot

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The human mirror system fMRI
OBSERVATION OF MOUTH MOVEMENTS HAND
MOVEMENTS FOOT MOVEMENTS
Buccino et al. 2001, Europ. J. Neurosci.
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MELTZOFF
Imitation based on the neonate's capacity to
represent visually and proprioceptively perceived
information in a form common to both modalities.
Observations in six newborns- one only 60 minutes
old - suggest that the ability to use intermodal
equivalences is innate (Meltzoff and Moore 1977)
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Imitation

• Normal development
• Neonates can imitate a range of facial expression
  (Meltzoff Moore, 1970).
• Tongue protrusion
• Lip protrusion
• Mouth opening
• Toddlers imitate movements that they believe to
  have been performed intentionally by the model
  (Meltzoff, 1995).
• Imitation deficits in autism
• Impairment in spontaneous imitation of action on
  novel objects.
• Impairment in instructed imitation

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Imitation

• Evidence of imitation in birds.
• Pigeon and Quail
• Imitate the appendage (beak or feet) used to
  depress a lever.
• Carib grackles
• Imitate features of beak (closed pecking versus
  open prying).
• Imitate features of head (down vs up)