Fechner’s Law

Membrane Response V

Subjective Intensity I

Log S

Log S

Log S’o

Log So

Fechner’s law:                I = A  log (S/So)  for S > So                        I = 0                    for S < So S:  Physical stimulus intensity So: Threshold stimulus intensity A:  Constant

V = A’  log (S/S’o)  for the linear range S:    Physical stimulus intensity S’o: Threshold stimulus intensity A’:  Constant