Myers EXPLORING PSYCHOLOGY Module 14 Introduction to Sensation and Perception: Vision James A....
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Transcript of Myers EXPLORING PSYCHOLOGY Module 14 Introduction to Sensation and Perception: Vision James A....
Myers EXPLORING PSYCHOLOGY
Module 14
Introduction to Sensation and
Perception: Vision
James A. McCubbin, PhDClemson University
Worth Publishers
Sensation
Sensation the process by which our sensory
receptors and nervous system receive and represent stimulus energy
Perception the process of organizing and
interpreting sensory information, enabling us to recognize meaningful objects and events
Sensation Our
sensory and perceptual processes work together to help us sort out complex images
Sensation
Bottom-Up Processing analysis that begins with the sense
receptors and works up to the brain’s integration of sensory information
Top-Down Processing information processing guided by
higher-level mental processes as when we construct perceptions
drawing on our experience and expectations
Sensation: Basic Principles
Psychophysics study of the relationship between
physical characteristics of stimuli and our psychological experience of them
Light- brightness Sound- volume Pressure- weight Taste- sweetness
Sensation: Thresholds
Absolute Threshold minimum stimulation needed to detect
a particular stimulus 50% of the time Difference Threshold
minimum difference between two stimuli required for detection 50% of the time
just noticeable difference (JND)
Sensation: Thresholds
Subliminal when stimuli
are below one’s absolute threshold for conscious awareness
0
25
50
75
100
Low Absolutethreshold
Medium
Intensity of stimulus
Percentageof correctdetections
Subliminal stimuli
Sensation: Thresholds
Weber’s Law to be perceived as different, two
stimuli must differ by a constant minimum percentage (rather than a constant amount) light intensity- 8% weight- 2% tone frequency- 0.3%
Now you see it, now you don’t!
Sensory Adaptation- diminished sensitivity as a consequence of constant stimulation
Vision
Transduction conversion of one form of energy
to another in sensation, transforming of
stimulus energies into neural impulses
Wavelength the distance from the peak of one
wave to the peak of the next
Vision
Hue dimension of color determined by
wavelength of light Intensity
amount of energy in a wave determined by amplitude brightness loudness
The spectrum of electromagnetic energy
Vision: Physical Properties of Waves
Short wavelength=high frequency(bluish colors, high-pitched sounds)
Long wavelength=low frequency(reddish colors, low-pitched sounds)
Great amplitude(bright colors, loud sounds)
Small amplitude(dull colors, soft sounds)
Vision
Vision
Accommodation- the process by which the eye’s lens changes shape to help focus near or far objects on the retina
Retina- the light-sensitive inner surface of the eye, containing receptor rods and cones plus layers of neurons that begin the processing of visual information
Retina’s Reaction to Light- Receptors
Rods peripheral retina receptors detect black, white and gray for peripheral or twilight
conditions Cones
receptors near center of retina fine detail and color vision for daylight or well-lit conditions
Retina’s Reaction to Light
Optic nerve nerve that carries neural impulses
from the eye to the brain Blind Spot
point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there
Vision: Receptors
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
Pathways from the Eyes to the Visual Cortex
Visual Information Processing
Feature Detectors nerve cells in the
brain that respond to specific features
shape angle movement
Stimulus
Cell’s responses
Visual Information Processing
Parallel Processing simultaneous processing of several
aspects of a problem simultaneously
Visual Information Processing
Trichromatic (three color) Theory Young and Helmholtz three different retinal color receptors
red green blue
Visual Information Processing
Opponent-Process Theory- opposing retinal processes enable color vision“ON” “OFF”red greengreen red blue yellow yellow blue black whitewhite black
Visual Information Processing
Color Constancy Perceiving familiar objects as
having consistent color, even if changing illumination alters the wavelengths reflected by the object
Color-Deficient Vision
People who suffer red-green dificiency have trouble perceiving the number within the design
Opponent Process: Afterimage Effect