Vol.:(0123456789) 1 3 Psychological Research DOI 10.1007/s00426-017-0860-z ORIGINAL ARTICLE On the time-course of automatic response activation in the Simon task Ruben Ellinghaus 1  · Matthias Karlbauer 1  · Karin M. Bausenhart 1  · Rolf Ulrich 1   Received: 19 September 2016 / Accepted: 21 March 2017 © Springer-Verlag Berlin Heidelberg 2017 Proctor, 1995). In this paradigm, participants respond to a certain attribute (e.g., color) of stimuli which randomly appear on the left or right side of a fxation point. Usu- ally, a congruency efect is found: Participants react faster when the stimulus is presented on the same side as the cor- rect response key (congruent trials) compared to trials in which the stimulus is presented on the side opposite to the response key (incongruent trials). Hence, although irrel- evant to the task, the location information of the stimulus nevertheless infuences the response selection process. Experimental psychologists interested in the cognitive mechanisms underlying performance in the Simon task have moved beyond the analysis of mean reaction time (RT) to also analyze RT distributions (e.g., de Jong, Liang, & Lauber, 1994). Since collapsing data to mean RTs always means losing information, experimental manipulations that do not infuence mean RTs might still afect the shape of RT distributions (Balota et al., 2008; Heathcote, Popiel, & Mewhort, 1991; Townsend & Ashby, 1983). Also, model predictions can be compared against observed data on the level of RT distributions (Miller, 1982; Ruthruf, 1996; Sigman & Dehaene, 2005). The goal of the present inves- tigation was to examine distribution-level predictions moti- vated by the Difusion Model for Confict Tasks (DMC), a novel model of the mechanisms underlying the Simon efect recently proposed by Ulrich et al. (2015) in a man- ner that is consistent with recent neurophysiological results (Servant, White, Montagnini, & Burle, 2016). An elucidating approach for investigating the efects of experimental manipulations on RT distributions in confict tasks is the delta plot (DP), developed by de Jong et al. (1994). Consider an experiment in which RTs are meas- ured in two diferent conditions (e.g., congruent and incon- gruent trials). For each condition, RTs are rank ordered and divided into equal-sized bins. Then, conditions can Abstract The Simon efect (prolonged RT when the task-irrelevant stimulus location is incongruent with the response side) has been reported to decrease at longer RTs, which is refected in negative-going delta functions. This fnding has been attributed to gradual dissipation of the response automatically activated by the task-irrelevant location information. The Difusion Model for Confict Tasks (DMC, Ulrich, Schröter, Leuthold, & Birngruber, Cognitive Psychology 78:148–174, 2015) formally speci- fes the time-course of this automatic activation process as a pulse-like function. In contrast to alternative views, DMC is consistent with the notion that this time-course is unaf- fected by the presentation duration of the target stimulus. Therefore, we expected that delta functions are invariant against changes of stimulus duration. This prediction was verifed in two Simon task experiments. Consistent with this general result, DMC’s parameter τ which defnes the time-course of the automatic response activation was esti- mated to not meaningfully difer between short and long durations. We argue that our results are coherent with pro- cessing architectures that assume a transient automatic pro- cess that is virtually unafected by stimulus duration. Introduction The mechanisms underlying performance in cognitive con- fict situations are often investigated in the Simon paradigm (Simon, 1969; for reviews see Hommel, 2011 and Lu & * Ruben Ellinghaus ruben.ellinghaus@uni-tuebingen.de 1 Psychological Institute, University of Tübingen, Schleichstrasse 4, 72076 Tübingen, Germany