Sleep deprivation affects interference control: A diffusion model analysis.

Previous studies suggest that interference control may be unaffected by sleep deprivation based on the unchanged interference effects (reaction time [RT] differences between incongruent and congruent conditions), while ignoring the overall slower RTs after sleep deprivation. In the present study, we interpreted these results from a new angle using a variant of diffusion model, diffusion model for conflict tasks (DMC), and investigated whether and how interference control is affected by sleep deprivation. Mathematical derivations and model simulations showed that unchanged task-irrelevant information processing (i.e., unaffected interference control) may not lead to the observed unchanged interference effects when considering the overall slower RTs after sleep deprivation (due to either decreased drift rate of task-relevant information or increased decision boundary). Therefore, the unchanged interference effects do not necessarily indicate unchanged interference control. We then conducted a Simon task following one night of sleep deprivation or normal sleep, and fitted the DMC to the data. Experimental results showed that the Simon effect was reversed when most of the trials were incongruent, indicating that participants used learned spatially incompatible stimulus-response associations to predict responses. However, the Simon effects in both mean RTs and RT distributions were not significantly modulated by sleep deprivation. Model fits showed that the drift rate of task-relevant information decreased and the time-to-peak of task-irrelevant activation increased after sleep deprivation. These results suggest that central information processing was degraded after sleep loss, and most importantly, task-irrelevant activation increased after sleep deprivation as interference control was impaired. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Learned irrelevant stimulus-response associations and proportion congruency effect: A diffusion model account.

The increased Simon effect with increasing the ratio of congruent trials may be interpreted by both attention modulation and irrelevant stimulus-response (S-R) associations learning accounts, although the reversed Simon effect with increasing the ratio of incongruent trials provides evidence supporting the latter account. To investigate if learning irrelevant S-R associations is a common mechanism underlying the proportion congruency (PC) effect of the Simon task, we employed a variant of diffusion model, diffusion model for conflict tasks (DMC), to test which theory can simultaneously account for the mean reaction time (RT) and RT distribution patterns of the Simon effect in different PC conditions. Simulation results showed that the DMC modulating starting point according to learned irrelevant S-R associations rather than drift criterion or attention-related parameters (i.e., drift rate of controlled process, peak amplitude and time-to-peak of automatic activation) can simultaneously simulate the increase and reversal of the Simon effect and the different shapes of delta functions in different PC conditions. Moreover, when fitting to empirical data, the DMC adjusting starting point provided a good fit to the mean RT and RT distribution patterns of the Simon effect in different PC conditions. These results suggest learning irrelevant S-R associations (biasing starting point) may be a common mechanism underlying the PC effect of the Simon task. (PsycInfo Database Record (c) 2023 APA, all rights reserved).