How repeatable are Stevens’s power law exponents for individual subjects?

Research paper by Martha Teghtsoonian, Robert Teghtsoonian

Indexed on: 01 May '71Published on: 01 May '71Published in: Perception & psychophysics


Magnitude estimations of apparent length and apparent area were obtained for the same group of Ss over successive experimental sessions. Session-to-session correlations between individual exponents on a given continuum were positive and reliable for successive 24-h intersession intervals, but were not significant for a 1-year interval. In a second experiment on judgments of apparent area, when each stimulus was judged only once per session, the session-to-session correlation was reliable only when the intersession interval was zero. Six other intervals, ranging from 1 to 77 days, yielded nonsignificant correlations. When the constraints exerted by repeated judging are removed, the location of S’s exponent in a distribution of exponents is stable only for brief intervals. Thus the differences among exponents cannot reflect any persisting attributes of Ss’ sensory or judgmental processes.