When Forewarned Is Not Forearmed: No Evidence for Cue-Based Proactive Control in the spatial Stroop task

It is commonly assumed that people can use advance cues to proactively prepare for conflict from distracting stimulus features, yet empirical findings remain inconsistent. We hypothesized that that nature of stimulus-response (SR) mappings may be a key determinant of cue effectiveness, as vocal Stroop tasks (with non-arbitrary color-naming responses) have shown reliable cue benefits while manual Stroop tasks (with arbitrary key-press responses) typically have not. Across five experiments, we tested this hypothesis by using a spatial Stroop task with non-arbitrary SR mappings, where participants responded to the direction of arrow stimuli using spatially corresponding keys, while trying to ignore the spatially congruent or incongruent location of the stimuli. Despite robust congruency effects and optimal preparation conditions (100% valid cues, 2000ms preparation time), we observed no cue benefits in four experiments. Only when task difficulty was increased substantially (50ms stimulus presentation, Experiment 4) did cue benefits emerge, but exclusively for congruent trials. These findings document that non-arbitrary SR mappings are not a sufficient condition for ensuring cue-based engagement of proactive control, and suggest that cost-benefit calculations about control exertion may be a more promising candidate factor.