Neuroscience Animations

John H. Krantz, Hanover College,

Using the Media






Skin Senses

Statistical Concepts

Hanover College
Psychology Department

Fechner's Law vs. Steven's Law

Brief description and instructions (DRAFT):

Illustration of how Fechner's Law (S = kLog(I)) and Steven's Law (S = cIb) predict the relationship between the physical intensity (I) of a stimulus and the strength of our psychological experience (S for sensation). 

Fechner's law, shown in red is a logarithmic relationship controlled by the parameter k derived from Weber's law.  Use the k slider on the left side to see how k changes the predictions of how sensitivity changes as k changes.  Notice it is always curve that slows down because it is logarithmic.

You can put up to three different curves for Steven's law on the graph by clicking check boxes on the left side of screen.  For each curve you can adjust both the b and c parameters by slides for each curve.  Adjusting b changes the shape of the curve; adjusting c does not.

Click here to open the applet.  It will open a new window that will fill your screen.