Stimulus duration and grating persistence: an instance of the 100-msec rule?

Abstract

Recently, Bowling and Lovegrove (I 980} presented data on the persistence of sine wave gratings varying in spatial frequency and exposure duration. Persistence was measured as the blank interstimulus interval (lSI), which when alternated with the grating, produced a criterion judgment of a gap between presentations of the grating. For each spatial frequency (I, 4, and 12 cpd), persistence decreased linearly with a slope of approximately -.75 as duration increased for short durations. For longer stimulus durations, the rate of decline in persistence with increasing duration was reduced, the slope being approximately .13. The authors fitted two linear regression lines by the method of least squares to the data points for each spatial frequency. They do not report whether a better fit could be obtained with a nonlinear continuous function, but the case for the two-limb linear function is made in terms of the change in function occurring at approximately the critical duration obtained using threshold measures of critical duration with increasing spatial frequency (Breitmeyer & Ganz, 1977; Legge, 1978). However, the authors do note that the values of critical duration so obtained are somewhat shorter than those obtained by Legge (l978). The point of these comments is that although Bowlingand Lovegrove (1980) develop a plausible case for their analysis, it is not wholly convincing and another interpretation is possible. The purpose of the present note is to show an alternative analysis of their results that would lead to different conclusions about the relationship among spatial frequency, stimulus duration, and persistence. Bowling and Lovegrove (1980) use lSI as their dependent variable, thereby following a precedent set by Meyer and Maguire (1977). Boynton (1972) has