Reaction times are shaped by global and local stimulus-response frequencies

Humans adjust to statistical regularities in their environment. For example, responses to more frequent stimuli are faster and less error-prone than responses to less frequent stimuli. Here we ask whether this adjustment to relative stimulus-response frequencies is local, that is, specific for stimulus locations, or global, that is, generalized across stimulus locations. In two experiments, participants responded to two colours of stimuli presented with different relative frequencies in upper and lower locations on a monitor, but equal relative frequencies in left and right locations. In the first experiment, reaction times and error rates differed between responses to the stimuli with different relative frequencies presented at the upper and lower locations and less so for responses to the stimuli with identical relative frequencies at left and right locations; for left and right locations, the effect of relative frequency was accompanied by a modulation of the Simon effect. In the second experiment, additional stimuli presented in a central location served to equate the overall frequency of the stimulus colours and responses. In this experiment, only a small effect of relative frequency remained for responses to stimulus colours in upper and lower locations where they actually had different relative frequencies. According to these results, there are both a global, location-independent effect of relative stimulus-response frequency and a local, location-dependent effect. (PsycInfo Database Record (c) 2026 APA, all rights reserved).