The shifted Wald distribution represents a non-censored Wiener diffusion model of choice response times: Evidence from simulations and a Go/No-go task

Cognitive psychologists commonly strive to infer processes/constructs from chronometric data. In this regard, diffusion modeling of response times (RTs) from correct and erroneous responses using the Wiener distribution has become popular because it provides a set of interpretable parameters. An important precondition to estimate these parameters, however, is a sufficient number of RTs from erroneous responses. In the present article, we show by simulation that the parameters of the Wiener distribution can even be recovered from tasks yielding very high or even perfect response accuracies using the shifted Wald distribution. Specifically, we argue that error RTs can be considered as correct RTs that have undergone informative censoring. Such censoring can be accounted for by techniques of survival analyses that should also be applied whenever task trials are experimentally terminated prior to response execution. We illustrate our reasoning by fitting the Wiener and censored shifted Wald distribution to RTs from 101 participants who completed a Go/No-go task. In accordance with our simulations, Wiener and shifted Wald modeling yielded the same parameter estimates when the number of erroneous responses was predicted to be low. Moreover, the modeling of error RTs as censored correct RTs improved the parameter plausibility with narrow response time windows. Finally, we investigate the relation between the number of RTs and the precision of parameter estimates from Wiener and censored shifted Wald modeling, and provide R code for the convenient application of the outlined analytical procedures.