Stevens Power Law

Question	Answer
Fechners assumption and law	Fechner assumed that jnds were subjectively equal. equal sensation differences correspond to equal stimulus ratios. S=klogI
Straight line on a log-log scale	indicates a relationship between y and x that is power not logarithmic
Emperical data gave what type of function on a linear-log scale, and what did that mean?	You get a power relation (curved line), not a logarithmic relation (straight line). This meant that emperical data was incongruous with fechners law
Steven's power law	S=kI(exponent) Resulting in equal sensation ratios corresponding to equal stimulus ratios
Exponent tells us?	The relation between the ratios of S & I
Response linearity	I increases and also S increases at a constant rate
Response Compression	exponent<1 As I increases, S increases at a decreasing rate
Response Expansion	exponent > 1 As I increases, S increases at an increasing rate
Log law is?	An indirect measure of sensory magnitude But also consistent with category scaling (much lighter, lighter, heavier, much heavier)
Power law is?	A direct estimate of sensory magnitude Handles compression and expansion Versitile

Resource summary

	Created by cjjstone almost 10 years ago