Chapter 5 - Sensation & Perception
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define sensation and perception
Sensation is the stimulus-detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain. (bottom up) Perception is making sense of what our senses tell us- is the active process of organizing this stimulus input and giving it meaning. (top down)
what is psychophysics
the study of how physical stimuli are translated into psychological experiences
What two kind of sensory capabilities are studied by psychophysics researchers?
• The absolute limits of sensitivity • The difference between stimuli
eastyn is a psychophysicist, she asks “what is the smallest difference in brightness that we can detect?” what is she studying
the difference between stimuli
eastyn is a psychophysicist, she asks “ what is the softest sound or weakest salt solution that humans can detect what is she studying
the absolute limits of sensitivity
define transduction
the process whereby the characteristics of the stimulus are converted into nerve impulses
define synesthesia
condition in which the brain mixes up senses
name the two theories that attempt to explain the cause of synesthesia
Theory 1- the pruning of neural connections that occurs in infancy hasn’t happened Theory 2- Insufficient neural inhibition in the brain so input overflows to other areas
define the absolute threshold
lowest intensity at which a stimulus can be detected 50% of the time
once transduction occurs, specialized neurons called _________ ___________ break down and analyze the specific features of the stimuli
feature detectors
what do you call stimulus that is so weak or brief that although it is received by the senses it can’t be perceived consciously
subliminal stimulus
define decision criterion
a standard of how certain they must be that stimulus is present before they will say they detect it
explain signal detection theory
signal detection theory is concerned with the situational factors that influence sensory judgements when perception is more important, people have lower absolute thresholds perception is thus a decision
Why do signal detection theorists view stimulus detection as a decision?
There is no single point on the intensity scale that separates no detection from detection of a stimulus. There is a range of Uncertainty and people set their own decision criterion- a standard of how certain they must be that a stimulus is present before they will say they detect it.
What kind of personal and situational factors influence signal detection decision criteria?
Fatigue, expectation and the potential significance of a stimulus.
define the Difference threshold
the difference between two stimuli that people can perceive 50% of the time the “just noticeable difference”
explain Weber’s law
states that the difference threshold is proportional to magnitude of stimulus, varies for every stimulus
eastyn is blasting the new metro boomin album in the car the music seems loud at the beginning but by the end she get used to it what is this an example of
sensory adaptation
what is sensory adaptation
reduced sensitivity to a stimulus after constant exposure
explain fechners law
sensation increase with the logarithm of intensity, there is not a 1:1 relationship between physical intensity and psychological intensity
what is subliminal perception
perception below the absolute threshold
what is the cornea
Cornea- outer layer that focuses on light
what is the pupil
the black part an adjustable opening that can dilate or constrict to control the light coming in
what is the iris
controls dealation of pupils coloured