Outline for Psychology 100 Lecture:
Perception
I. Perception: The process through which raw sensations are interpreted, using knowledge and
understanding of the world, so that they become meaningful experiences.
A. Three Approaches to Perception:
1. Computational:
2. Constructivist: Representations are built up from bits of sensory information and
prior experience
3. Ecological:
B. Psychophysics:
1. Threshold:
a.) Absolute Threshold: minimum stimulus energy that can be reliably
detected 50% of the time
b.) Subliminal Stimuli:
c.) Supraliminal Stimuli:
C. Organizing the Perceptual World:
1. Perceptual Organization: task performed by perceptual system to determine what
edges and other stimuli go together to form an object (and to separate that object
from its background of other competing stimuli).
2. Figure-Ground Organization:
a.) Figure:
b.) Ground: the background that contains the figure
c.) Reversible Images:
3. Grouping:
a. Gestalt Psychologists: early researchers of how people perceive sights and
sounds as organized wholes.
i. Gestalt Laws:
- Proximity:
- Closure: the tendency to fill in missing contours to form complete
objects
- Similarity:
- Continuity: sensations that appear to create a continuous form are
perceived as belonging together
- Common Fate:
- Synchrony: stimuli that occur at the same time are likely to be
perceived as belonging together
- Common region:
- Connectedness: elements that are connected by other elements
tend to be grouped together
b. Why do we organize incoming stimuli this way?
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i. likelihood principle: we likely group stimuli this way because it is the
way stimuli are likely to be organized in the natural world.
ii. simplicity principle:
4. Perception of Location and Distance:
a. Depth Perception: the ability to perceive distances to objects and 3dimensional characteristics of objects
i. Monocular Depth Cues:
- Interposition:
- Relative Size: if two objects are assumed to be the same size, the
object producing a larger image on the retina is perceived as closer
- Relative Height:
- Texture Gradient: Texture appears less detailed as distance increases
- Linear Perspective:
- Clarity: clarity reduces with distance.
- Light/Shadow:
- Motion Parallax: When moving, objects nearer seem to move faster in
the visual field than objects in the distance.
ii. Binocular Depth Cues:
- Convergence: the degree to which muscles rotate your eyes to focus on
an object – the more your eyes converge (rotate inward) to focus, the
closer the object is perceived to be.
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- Binocular Disparity:
5. Perception of Motion:
a. Looming:
b. Induced Motion: illusion based on assumption that background is stationary
c. Stroboscopic Motion:
6. Perceptual Constancy: Tendency to perceive objects as constant despite changing
sensory input
a. Size Constancy:
b. Shape Constancy: the tendency to perceive objects as having a fixed shape,
despite changing retinal images
c. Brightness/Color Constancy:
7. Types of Processing:
a. Bottom-Up:
b. Top-Down:
c. Network Processing:
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- Object Superiority Effect: Features easier to detect if imbedded in a
familiar object
- Word Superiority Effect:
- Parallel Distributed Processing: various elements of a given object are
thought to be simultaneously analyzed by many widely distributed, but
connected, neural units in brain
8. Culture and Perception:
9. Attention: Process of directing & focusing our resources to enhance perception,
performance, & mental experience
a. 3 Important Characteristics:
b. Directing Attention:
- Voluntary: purposely focusing attention to perform a task.
- Involuntary:
c. Inattentional Blindness:
d. Divided Attention (AKA “Multitasking”): we commonly divide our
attention so we can do more than one thing at a time
- Stroop Task:
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