PSYCH 2GG3 Chapter Notes - Chapter 2.2: Absolute Threshold, Just-Noticeable Difference, Psychophysics
Chapter 2.2 –
psychophysics
The beginnings of scientific psychology
Early psychologists:
- relied heavily on introspection for investigating human behaviour
o Using it helped to systematically analyze and interpret personal thoughts, feelings
and arrive at conclusions that could be generalized
o Aka ‘armchair research’ :
▪ used by Descartes
- Structuralist movement:
o strongly influenced by biology and physiology
o Relied on the study of the mind
Early psychophysics:
- this is the measurement of physical stimuli and their effects
absolute threshold:
o determining this for each sense =
▪ finding the least amount of stimulation required for sensation
o not possible b/c no single level of light / sound that always leads to sensation
(some people more sensitive than others)
o for each person though, there I a lower limit which a stimulus will never be
detected and an upper limit which it will always be detected
o between the two, the point at which it will be detected 50% of the time –
▪ the absolute threshold
differential threshold:
o aka the ‘just noticeable difference’ (JND)
o these are at a constant proportion of a stimulus
o ex: when noticing the difference between weights of 1 and 2 pounds, this is a
noticeable difference
o interested in finding the least amount of change in stimulation that would be
noticeable
Ivan Pavlov (1849-1936):
Classical conditioning:
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