Psychology 1000 Lecture Notes - Hair Cell, Sound Intensity, Vestibular System

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Published on 17 Apr 2013
School
Western University
Department
Psychology
Course
Psychology 1000
Professor
Lecture 1: Sensory and Perceptual Processes
Sensation and Perception
Sensation
The process by which our sense organs respond to and translate stimuli into
nerve impulses sent to the brain
Perception
Organizing the stimulus input and giving it meaning
Stages of Sensation and Perception
1. Stimuli activate sensory receptors
2. Sensory receptors translate information into nerve impulses
3. Specialized neurons and analyze stimuli features
4. Stimulus pieces are reconstructed and compared to stimuli in memory
5. Perception is then consciously experienced
Psychophysics: Sensitivity to stimuli
Absolute limits of sensitivity
o Dimmest light in which we can see objects
o Softest sound we can hear
Recognizing differences between stimuli, measure the difference between
what you can and can’t sense
o Smallest difference in brightness detectable
o Recognizing differences between tones
Stimulus Detection
The lowest intensity at which a stimulus can be detected 50% of the time
However, the environment contains a background level of stimulation for
each sense and this level (the ADAPTION level) must be overcome if a
stimuli is to be detected
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The Absolute Threshold
Going to plot the amount of positive responses at
50.
Generic chart for psychophysics.
At: 50% say it is there and 50% say its not that is
our Absolute Threshold
Measured in units of physical energy depending
on the type of sensation
Below 50% we don’t count because it is below
guessing, everything over that is better than
guessing
You have to take the absolute limit because it is
the limit between below and above guessing.
Examples of
absolute
threshold for
all your senses
However, the environment contains a background level of stimulation for each
sense and this level (the Adaption level) must be overcome if stimuli is to be
detected
Background contains a level of stimulation for each sense and this level
needs to be overcome
Sometimes this signal will be able to overcome
Differential Threshold
The amount of energy required to overcome the Adaption level
Is subject to variation with changes in circumstances
Locke’s Experiment
Materials: 3 buckets/large bowls
Method: fill 1 with very hot water, 1 with cold water, 1 with tepid water.
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Procedure: subject closes eyes place one hand in hot and the other in cold
for approx 3 minutes. Then place both hands in tepid water
Ask subject to report sensation for each hand separately
Instruct subject to open eyes
Although both hands are in the same water the sensations differ to the prior
Adaptation, they adapted to the hot and cold water and it exceeded
adaption level.
Signal Detection Theory
Detection Criterion: A personal standard of certainty before a person will
say that they detect a stimulus, brought into play when they report into you.
o Affected by:
Conservativeness (require more info) or Boldness (require
less info)
Increasing rewards for hits or costs for misses
If you say yes and it is there, if you say no and it is not
there = hit
If you say yes and it is not there, if you say no and it is
there = miss
o Bold subjects show high hits and high false alarms
o Conservative subjects show high misses and correct rejections
o However, Criterions can be manipulated by changing the payoff for each
cell of the response matrix: going to create a bolder subject
o This shows perception is, to some extent, a decision
Subliminal Perception
A subliminal stimulus cannot be perceived consciously but do register in the
nervous system
Bold high in these cells
Conservative high in
these cells
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Document Summary

The process by which our sense organs respond to and translate stimuli into nerve impulses sent to the brain. Organizing the stimulus input and giving it meaning. Stages of sensation and perception: stimuli activate sensory receptors, sensory receptors translate information into nerve impulses, specialized neurons and analyze stimuli features, stimulus pieces are reconstructed and compared to stimuli in memory, perception is then consciously experienced. Absolute limits of sensitivity: dimmest light in which we can see objects, softest sound we can hear. Recognizing differences between stimuli, measure the difference between what you can and can"t sense: smallest difference in brightness detectable, recognizing differences between tones. The lowest intensity at which a stimulus can be detected 50% of the time. However, the environment contains a background level of stimulation for each sense and this level (the adaption level) must be overcome if a stimuli is to be detected. Going to plot the amount of positive responses at.

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