Page 181 - Foundations of Cognitive Psychology : Core Readings

Perception 185

rator, a perceiver is constantly rearranging the stimuli so that they fit better and
are more coherent. Incongruity and messy perceptions are rejected in favor of
those with clear, clean, consistent lines.
If perceiving were completely bottom-up, you would be bound to the same
mundane, concrete reality of the here and now. You could register experience
but not profit from it on later occasions, nor would you see the world differ-
ently under different circumstances. If perceptual processing were completely
top-down, however, you could become lost in your own fantasy world of what
you expect and hope to perceive. A proper balance between the two extremes
achieves the basic goal of perception: to experience what is out there in a way
that maximally serves your needs as a biological and social being moving about
and adapting to your physical and social environment.

Recapping Main Points

Sensing, Organizing, Identifying, and Recognizing
Your perceptual systems do not simply record information about the external
world but actively organize and interpret information as well. Perception is a
three-stage process consisting of a sensory stage, a perceptual organization
stage, and an identification and recognition stage. At the sensory level of pro-
cessing, physical energy is detected and transformed into neural energy and
sensory experience. At the organizational level, brain processes organize sen-
sations into coherent images and give you perception of objects and patterns.
At the level of identification, percepts of objects are compared with memory
representations in order to be recognized as familiar and meaningful objects.
The task of perception is to determine what the distal (external) stimulus is
from the information contained in the proximal (sensory) stimulus. Ambiguity
may arise when the same sensory information can be organized into different
percepts. Knowledge about perceptual illusions can give you clues about nor-
mal organizing processes.

Attentional Processes
Attention refers to your ability to select part of the sensory input and disregard
the rest. Both your personal goals and the properties of objects in the world
determine where you will focus your attention. Attention accomplishes its tasks
by both facilitating the processing of the relevant, attended stimuli and sup-
pressing the processing of irrelevant, unattended stimuli. Preattentive process-
ing enables you to search the visual environment efficiently, although focused
attention is required in many cases to find combinations of features. Attention
also allows simple physical properties of objects to be combined correctly.

Organizational Processes in Perception
Organizational processes provide percepts consistent with the sensory data.
These processes segregate your percepts into regions and organize them into
figures that stand out against the ground. You tend to see incomplete figures
as wholes; group items by similarity; and see ‘‘good’’ figures more readily. You
tend to organize and interpret parts in relation to the spatial and temporal