Cognitive Psychology

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Cognitive Psychology

• Chapter 3

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Visual Consciousness

• Transduction of the visible spectrum (400 nm to
  700 nm) of electromagnetic radiation.
• Crossing of the visual pathways from retina to
  primary visual. Left visual field
• represented in right hemisphere.

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Visual Consciousness

• A critical periods for cortical development in
  cats show that primary visual cortex is necessary
  for visual consciousness.
• Blindsight in humans Damage to primary visual
  cortex eliminates visual consciousness but a
  second pathway allows accurate discrimination.

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Types of Agnosia

• Apperceptive Agnosia object recognition fails
  because of difficulties in identifying the visual
  features of a perceptual category.
• Associative agnosia object recognition fails
  because of difficulties in identifying the
  functional features that define a semantic
  category.

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Pattern Recognition

• Refers to the step between the transduction and
  perception of a stimulus in the environment and
  its categorization as a meaningful object.
• Agnosiafailure of pattern recognition caused by
  brain lesions.

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Top-down vs. Bottom-up Processes

• Organized knowledge representations called
  schemas direct exploration of objects and events
  in the environment.
• Conceptually-driven processes provide
  expectations from the top-down.
• Data-driven processes sample features from the
  bottom-up.

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Word Superiority Effect

• WORK vs. ORWK vs. K
• Surprisingly, a single letter (K) is recognized
  faster in the context of a whole word (WORK) than
  when presented as an isolated letter. A nonword
  (ORWK) doesnt provide this top-down advantage.

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How are objects represented?

• Distinctive feature lists may suffice for printed
  letters (Z is detected faster here OQBZPD than
  here TLKZMV).
• But the structural relations among features are
  often as important as the features themselves.

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Face Perception

• Holistic vs. Analytic Processing
• Faces are unique in that holistic processing is
  much stronger than analytic processing for them
  as compared with other objects.

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Speech Recognition

• Phonological segments that signal meaning
  (phonemes) unfold at 12/s or more. Fast,
  effortless processing of 40,000 bits/s implies a
  speech module.
• The structural relations among phonemesthe
  context in which a phoneme occursis critical to
  recognition.

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Why context is important?

• Co-articulation Each segment of speech provides
  clues about more than one phoneme. That is,
  multiple phonemes are articulated at the same
  time.

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Why context is important?

• Co-articulation Each segment of speech provides
  clues about more than one phoneme.
• Phonemes lack invariant distinctive features

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Top Down Processing

• Phonological segments are continuous in speech.
  Pauses heard are often illusions constructed by
  imposing phonemes from the top.
• Subtle variations are ignored unless they fall at
  phoneme boundaries (categorical speech
  perception).

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