1. Myers’ EXPLORING PSYCHOLOGY (6th Ed)
Chapter 5
Sensation & Perception
Modified from:
James A. McCubbin, PhD
Clemson University
Worth Publishers

2. Sensation & Perception
Process by which sensory receptors & nervous system receive & represent stimulus energy
Perception
Process of organizing & interpreting sensory info, enabling us to recognize meaningful objects & events

3. Sensation & Perception
Bottom-Up Processing
Begins with sense receptors & works up to brain’s integration of sensory info
Top-Down Processing
Guided by higher-level mental processes
Construct perceptions drawing on experience & expectations

4. Sensation: Basic Principles
Psychophysics
Study of relationship between physical characteristics of stimuli & psychological experience of them
Light - Brightness
Sound - Volume
Pressure - Weight
Taste - Sweetness

5. Sensation: Thresholds
Absolute Threshold
Minimum stimulation needed to detect particular stimulus 50% of time
Difference Threshold (JND)
Minimum difference between 2 stimuli required for detection 50% of time
Increases in proportion to size of stimulus
Weber’s law

6. Sensation: Sensory Adaptation
Diminished sensitivity as consequence of constant stimulation
Enable us to focus on informative changes

7. Vision
(Contains Rods & Cones)

8. Vision: Receptors in retina
Receptors in the Human Eye
Cones
Rods
Number
Location in
retina
Sensitivity in
dim light
Color sensitive?
Yes
Low
Center
6 million No
High
Periphery
120 million

10. How the Brain Perceives
Necker
Cube

11. Perceptual Organization
Gestalt
Organized whole
Tendency to
integrate pieces of information into
meaningful wholes

12. Perceptual Organization: Form Perception
Figure-Ground-Organize visual field into objects (figures) that stand out from surroundings (ground)

13. Perceptual Organization: Form Perception-Grouping
Organize stimuli into coherent groups using certain principles
Proximity
Similarity
Continuity
Connectedness
Closure

14. Perceptual Organization: Form Perception-Grouping

15. Perceptual Organization: Form Perception-Grouping
Closure
Gestalt grouping principles are at work here.

16. Perceptual Organization: Depth Perception
Ability to see objects in 3D
Helps judge distance
Binocular cues (2 eyes)
Retinal disparity
Images from 2 eyes differ
Closer object, larger disparity
Convergence
Neuromuscular cue
2 eyes move inward for near objects
Monocular cues (1 eye)

17. Perceptual Organization: Depth Perception
Monocular Cues
Relative size
Interposition
Relative height
Linear perspective
Light & shadow
Relative motion

18. Perceptual Organization: Depth Perception
Perspective Techniques

19. Perceptual Organization: Depth Perception
Light and Shadow

20. Perceptual Organization: Depth Perception

21. Perceptual Constancy Perceptual Constancy Shape Constancy
Perceiving objects as unchanging even as illumination & retinal image change
Shape Constancy
Size Constancy

22. Perceptual Constancy: Size-Distance Relationship