RELATIONSHIPS BETWEEN THE VL AND REACTION-TIME MODELS

The VL concept is based on measurements of accuracy thresholds where r esponse times are essentially unlimited. Pea has produced a visual per formance model based on reaction times, which include response times. Analysis of phenomena such as the Pulfrich illusion suggest that there is a delay between signal onset and recognition that depends upon the adaptation luminance. This suggests an analysis of reaction times in terms of a simple sum of a signal strength (VL) term plus response ter m(s), including a delay term. A comparison of Pea's reaction-time mode l and this additive VL model showed that the models are similar, but t hat the VL model fits the data better and has a more consistent theore tical foundation. The luminance-dependent response term appears to be needed to fit performance on the numerical verification task developed by Pea, but not the word chart reading task developed by Bailey. The above additive VL model suggests that the difference may depend on whe ther the task is processed serially and includes the delay time, or is processed in parallel and does not.