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Lecture 19

Chap 4: Sensation and Perception {Lecture 19}

Course Code
PSYC 1010
Rebecca Jubis

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Tuesday, March 13, 2012
Chapter 4: Sensation and Perception
Sensation: the process whereby our sensory organs gather information from the exter-
nal world (stimulation of sensory organ)
Perception: the process whereby the brain organizes and interprets these sensation so
that they have some meaning.
Psychophysics: the study of how physical stimuli are translated into psych experience
How much of a S is necessary for you to detect it?
1. Absolute threshold is the point at which a person can detect the lowest light intensity
50% of the time.
60 candles +1
120 +2
240 +4
2. Difference Threshold is the smallest difference in stimulation to discriminate on S
from another 50% of the time.
Weber’s Law
People are to perceive very small changes if the magnitude of the reference S is
small, but as the magnitude of reference S increases, a greater change is neces-
sary before a difference is perceived.
3. Signal Detection Theory : it proposes that the detection of S is based on:
a. The actual intensity of the S
b. Noise (irrelevant S)
c. Decision process or response criterion
There’s a difference in the level that people sense a S
introverts are less likely to make risky decisions, and extroverts,
vice-versa, so they are probably more likely to say that they see the light
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