Two models for an inspection time paradigm: Processing distraction and processing speed versus processing speed and asymptotic strength

Abstract

In an inspection time (IT) paradigm, the IT stimulus was presented at six exposure durations varying from 16 to 100 ms and subject accuracy was observed for each duration. The exposure time-accuracy functions were then modeled in terms of a processing-distraction/processing-speed (PDPS) approach and a pure processing-speed approach based on a restricted version of McClelland's (1979) “cascade” framework. Neither of the two-parameter approaches accounted for the observed individual time-accuracy functions that, on average, asymptote below 100%. However, both models fit if the performance asymptote was allowed to vary between subjects, either from differences in random errors introduced into IT responding (for PDPS) or from differences in the memory strength for IT stimuli among subjects (for cascade). Study 2 favored the memory-strength interpretation of the asymptote because the asymptote parameter correlated with fluency on a skill that was expected (from theory) to be limited by memory strength.