8. Sensation: Receiving Messages
About the World
• Sense organs
– See, hear, taste, smell, touch, balance, and
experience the world
– Sensory receptor cells transmit sensation
– Perception – interpreting information and
forming images
– Top-down / bottom-up
9. Feature Analysis
• Lines or edges
• Geons
• Phonemes
• Parts of a face (eyes, nose…)
Bottom-Up Processes
11. Feature Search
Feature Search: searching for a target that differs from all
distracters by a unique feature.
Conjunction Search: searching for a target that has a particular
combination of the distracters' features.
12. Top-Down Processing
• We perceive by filling
the gaps in what we
sense.
• I _ant ch_co_ate ic_
cr_am.
• Based on our
experiences and
schemas.
13. Bottom-Up and Top-Down Processing
working together
Word Perception
• Connectionist Model
14. An example of context effects in perception.
Word Perception: Top-
Down Processing
15. Perception
• Perceptual processes include:
– Selection refers to choosing
which of many stimuli that will
be processed.
– Organization involves collecting
the information into some
pattern.
– Interpretation involves
understanding the pattern.
• Perception is not passive
• Perceptions can be in error
– Illusions are visual stimuli that
are misinterpreted .
17. Perceived Motion
• Phi phenomenon
– When two lights flash at
a certain speed, we
perceive a singular light
oscillating back and forth.
– Apparent movement: (see
movement when no
movement has actually
taken place)
21. Gestalt Organizational Principles
• The German word
gestalt can be translated
to mean form, pattern,
configuration.
• This configuration or
pattern offers an
“organization” to
perception which the
individual experiences.
27. Perceptual Constancies
Size Constancy Shape Constancy
Kohler’s TRANSPOSITION: when we attend to an object
we also attend to its RELATIONSHIP with other objects
29. Visual Agnosia
• Apperceptive Visual Agnosia
– Cannot recognize by shape
– Cannot copy drawings
– Often involves
‘prosopagnosia’
• Associative Visual Agnosia
– Can copy, but unaware what
it is; cannot assign meaning
to object
– Difficulty in transferring
visual info into words
32. Are faces unique?
The case of face inversion:
– People are generally better at
recognizing upright faces than
other objects.
– However people are worse at recognizing inverted
faces compared to other inverted objects.
