Pattern Recognition Flashcards
what is the main problem with forming representations of objects?
shape constancy - objects can appear in many different orientations, therefore limiting theories of perception
what are theories of bottom-up pattern recognition?
template theory
feature theory
RBC theory
template theory
uses pattern activity to perceive objects
whatever memory representation most closely matches the object is what one thinks the object is
problems with template theory
transformations
obstructed objects
doesn’t involve features
feature theory
counts up matching feature between perceptual and memory representations
what is evidence supporting feature theory?
the visual system uses features
caricatures are recognized better than realistic line drawings
problem with feature theory
doesn’t account for the relationship between features
RBC theory
uses features to deconstruct objects into geons
geon
basic geometric shape
RBC theory matching process
detect object
find view-invariant properties of the object
determine the component geons using view-invariant properties
match geons to memory
what is evidence supporting RBC theory?
allows one to recognize partial or degraded objects
the more complex an object is, the easier it is to recognize it
harder to recognize objects in unusual orientations
problems with RBC theory
little neuroscientific supporting evidence
doesn’t explain how one can distinguish similar objects from each other
doesn’t account for recognizing objects when not in their usual contexts
bottom-up pattern recognition is driven by what?
stimulus data
top-down pattern recognition is driven by what?
prior knowledge and past experiences
types of top-down effects
expectation/bias
environmental context effects
word superiority effect
expectation/bias effect
your own expectations/biases can affect one’s perception of something
signal detection theory
neural activity increases when a signal is detected among noise
signal
something in the environment one is trying to detect
noise
things in the environment other than the signal
sensitivity
how well one discriminates a signal from noise
decision criterion
the level of activity required to determine that a signal is present
aka the threshold
“yes” bias
more likely to say a signal is present than that it’s not present
caused by lowering the decision criterion
“no” bias
more likely to say a signal isn’t present than that it is present
caused by raising the decision criterion
what does response accuracy depend on?
bias
sensitivity
proportion of “yes” responses and “no” responses
environmental context effects
when the perception of an object is affected by its context or environment
examples of environmental context effects
subjective contours
ambiguous letters
objects out of context
word superiority effect
it is easier to identify a letter when it’s presented in the context of a word than when it’s presented alone
results of the forced-choice task
words are remembered better than non-words and single letters
pronounceable non-words are remembered better than unpronounceable non-words
