How do we perceive the world around us ?
Psychophysics and psychophysiology
psychophysics: relation between physical stimulus and psychological
Fechner: father psychophysics
Value of stimulus characteristic required to produce some respose
Difference threshold: amount of change for jnd
Absolute: lower limit
vision: candle flame at 50km
hearing: tick of a watch at 6m
taste: tsp. of sugar in 8l. of water
smel: 1 drop of perfume in a 6 room apt
touch: wing of a fly on cheek from 1 cm
so whats the realtion?
brightness and perceived brightness
not a 1-1 relation
size of difference threshold relative to physical intensity of test is constant
delta I/I = constant
if I = 50db and a jnd is reported at 55db
1. can predict other JND’s
E.G whats a JND @ 100 db?
deltaI = 10
a JND would occur @ new test +10 = 11-db or
new test – 10 = 90db