PSYB57H3 Chapter Notes - Chapter 3: Dentil, Q Code, Bigram

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17 Mar 2012

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Chapter 3 Recognizing Objects
Visual Perception- How do you perceive and recognize objects?
- Form perception: Process where you manage to see what basic shape and size of object is
- Object recognition: Process of identifying object
Why is Object Recognition Crucial?
- All knowledge is on form perception and object recognition, without recognition, you
cannot bring your knowledge onto the world
- Object recognition important in learning combining new information with previous
information, categorization
Beyond the Information Given
- Group of psychologists in 20th century, ”Gestalt psychologists” noted that or
perception of visual world is organized by the ways that the stimulus input is
not” – organization must be contributed by perceiver
- Jerome Bruner voiced similar claims and coined “beyond the information given “to
describe some ways that perception of stimulus differs from the stimulus itself
- The Necker cube: Ambiguous figure b/c there is more than 1 way to see it
- Figure/ground organization: Determination of what is the figure and what is he
Organization and “Features”
- Some say perception of world is in two step: Collection information about stimulus
and interpreting information = WRONG
- Lateral inhibition where visual system emphasizes some aspects of input and
deemphasize others
- Number of observations suggest that our interpretation, organization of input, happens before we start
cataloguing the input’s basic features, and not after, as secondary “interpretative” step
- On one side, our perception of any form must start with stimulus and must be governed by what is in that
The Logic of Perception
- Stimulus does not tell you which elements of the input are figure and which is ground, or how the form is
arranged in 3D
- Organizing themes must be imposed on stimulus by perceiver, the organization is “in the eye of the beholder” and
not in stimulus itself
- These are not “add-ons” late in process of perception proceed in parallel with the earliest’ pickup information
- What matters for familiarity is the figure task perceived the figure plus the specification added by the perceiver
and if these specifications change, the familiarity is lost
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Object Recognition
Recognition: Some Early Considerations
You can recognize huge number of different
pattern, can also recognize objects when information
is partial, as well as print, various objects.
- Many objects are recognized by virtues of their parts
- Recognition might begin with identification of features in input pattern features such as vertical lines,
curves, diagonals
- The features we use are ones in our organized perception of input features [present in our organized perception
of forms, and this returns us to our proposal we recognize objects by detecting the presence of relevant features
- Advantages: Futures serve as general-purpose building blocks, allows us to concentrate on what is common to
various object features have priority in our perception of world, detection of features is a separate step in object
recognition, flowed by subsequent steps where features are assembled into more complex wholes
- Visual search task: Participants have to indicate in what terms a single prominent feature (i.e. searching
for angular shape hidden in group of circle); participants can locate target difference between angles and
curves jumps out immediately, like differences in colour, orientation and other features
- Integrative agnosia: Damage to parietal cortex impaired in tasks that require them to judge how the
features are bound together to form complex objects
- Similar results obtained in transcranial magnetic stimulation/TMS used to disrupt portion of brain in healthy
individuals impairment in parietal lobe mean slower performance when searching for target defined by
conjunction of features )”Find the shape that is red and round”)
Word Recognition
Factors Influencing Recognition
- Participants have shown stimuli for 20-30 ms
- Older research did this by tachistocope device used to present stimuli for precisely controlled amounts of
- Each stimulus followed by post-stimulus mask random jumble of letters (i.e. XKSDJF) interrupts
continued processing
- Jacoby and Dallas (1981) showed their participants words that were either very frequent or infrequent viewed
for3 ms, followed by mask recognized 65% of frequent but only 33% for infrequent - ADVANTAGE FOR
- Participants for second exposure repetition priming
i.e. participants were when series of words in tachistocope some words were primed while others word.
Words high in frequency 68% for unprimed, 84% for primed; words low in frequency 37% for unprimed, 73%
The Word Superiority Effect
- Word-superiority effect: Words are easier to perceive as compared to isolated letter
- Demonstrated w/ “2-alternative, forced-choice” procedure – we might present a single letter followed by post-
stimulus mask with question “:Was there an E or a K in display?” or present word DARK – followed by mask,
flowed by “Was there an E or a K in the display?”
50-50 chance
Addition for word stimulus would either create common word saw only part of the display and have to choose
the relevancy
Accuracy rates are higher in word condition recognizing words is easier than recognizing isolated letter
Degrees of Well-Formedness
- Will the context produce the same effect?
- Having a context is helpful even if the context is neither familiar or meaningful not all context provide
advantages (i.e. H would not be helpful for context such s HSDF or HOZD
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