Chapter 3- Perceiving objects and recognizing patterns

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Published on 9 Feb 2011
School
UTSC
Department
Psychology
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PSYB57H3
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PSYB57- Chapter 3- Perceiving objects and recognizing patterns
Perception- taking sensory input and interpreting it meaningfully
Neuroscientists have estimated that the areas of our brain responsible for visual
processing occupy up to half of the total cortex space
The main problem with perception is explaining how we attach meaning to the
sensory information we receive
Perception can be divided into visual, auditory, olfactory, haptic, and gustatory
perception
Distal stimulus- an object, event or pattern as it exists in the world. For a living
organism to process information about these stimuli, it must first receive the
information through one or more sensory systems
Proximal stimulus- the reception of information and its registration by a sense
organ
Retinal image- a proximal stimulus for vision, consisting of the projection of light
waves reflected from stimuli and projected to a surface at the back of the eye. This
image in 2-D and its size depends on you distance from the window and the objects
beyond (the closer you are to the image the larger it is).
the meaningful interpretation of the proximal stimulus is the percept
percept is not the same as proximal stimulus
Size constancy- the phenomenon that ones perception of an object remains
constant even as the retinal image of the object changes size
Perception involves something different from the formation of retinal images
Related to perception is a process called pattern recognition- this is the
recognition of a particular object, event, as belonging to a class of objects, events, etc.
Because the formation of most percepts involves some classification and recognition,
most instances of perception involve some pattern recognition
Gestalt approaches to perception
Form perception- the segregation of the whole display into objects (a.k.a. figure)
and the background (a.k.a. the ground)
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the part of the display seen as the figure is seen as having a definite shape, as being
some sort of thing and is better remembered than the part of the display interpreted
as the ground, which is seen as more shapeless, less formed and farther away in
space
form perception is a cognitive task most of us perform quickly and easily and thus for
granted
Subjective/ illusory contours- illusory outline created by certain visual cues that
lead to erroneous form perception. The existence of this phenomenon suggests that
perception is an active constructive process, which means that perception is not
completely determined by the stimulus display; it requires the participants active
participation. We make a simplifying interpretation without being aware of it
Gestalt psychologists rejected the claim that we recognize objects by identifying
individual features or parts; instead we see and recognize each object or unit as a
whole
Gestalt principles of perceptual organization- these allow us to see objects as
wholes. 5 major principles: 1) proximity- nearness; we group things together that are
nearer to each other; 2) similarity- we group things that are similar to each other; 3)
good continuation- we group objects together whose contours form a continuous
straight or curved line; 4) closure- like the subjective/ illusory contour; even though
there are no lines in a display we tend to fill in the gaps to perceive a whole object; 5)
common fate- elements that move together will be grouped together
Most of the Gestalt principles are included under a more general law, the law of
Pragnanz. This law states that of all the possible ways of interpreting a display, we
will tend to select the organization that yields the simplest and most stable shape or
form
Thus, simple and symmetric forms are seen more easily than more complicated ones
With the Gestalt approach, we just dont know how these principles are translated to
cognitive and physiological processes
Bottom-up processes
Bottom-up processing- the perceiver starts with small bits of information from the
environment that they combine in various ways to form a percept; you would form a
perception from only the information in the distal stimulus; the system works in one
direction, starting from the input proceeding to a final interpretation
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Document Summary

Because the formation of most percepts involves some classification and recognition, most instances of perception involve some pattern recognition. The existence of this phenomenon suggests that perception is an active constructive process, which means that perception is not completely determined by the stimulus display; it requires the participant"s active participation. We make a simplifying interpretation without being aware of it. Feature analysis: some psychologists believe such analysis of a whole into its parts underlies the basic processes used in perception. Instead of processing stimuli as whole units, we break them down into their components using our recognition of those parts to infer what the whole represents www. notesolution. com: the parts searched for and recognized are called features. In other words, they found evidence of separate horizontal line detectors and vertical line detectors as well as other distinct detectors: certain detectors appear to scan input patterns looking for a particular feature. If a demon finds such a feature, it screams.