Fig 1.
Stimulus display, spatial arrangement of response buttons, and trial timing.
Panel A shows the typical stimulus display and response button layout in Experiments 1, 2, and 4. Panel B illustrates a typical trial. Numbers in Panel A schematically indicate which buttons of the response box were used in the experiments; actually, buttons were not labelled. The same timing of stimulus elements applied in all four experiments.
Fig 2.
Pseudowords were associated with color and/or response position in the Stroop task, yielding congruent (p = .8) and incongruent (1–p = .2) trials (p denotes the probability of a congruent trial for a given pseudoword). Two example trials are shown for each contingency condition. Note that for ColPosFix trials only, the spatial order of the color squares remained fixed throughout.
Fig 3.
Mean response times (A) and net effects (B) in Experiment 1. Error bars are within-participant standard errors of the mean. Abbreviations: Col = color contingency, Pos = response position contingency, ColPos = both contingencies, ColPosFix = both contingencies plus fixed spatial arrangement of the response cues. Effects: Congruency = RTincongruent–_RTcongruent, Facilitation = RTneutral–_RTcongruent, Interference = RTincongruent–_RTneutral.
Fig 4.
Mean response times (A) and net effects (B) in Experiment 2. Participants were informed about the contingency type before each upcoming block. Error bars and abbreviations as in Fig 3.
Fig 5.
Mean response times (A) and net effects (B), collapsed over Experiments 1 and 2. Error bars and abbreviations as in Fig 3.
Fig 6.
Stimulus display and spatial arrangement of response buttons in Experiment 3.
Numbers on the response buttons are for illustrative purpose; they were not labelled in the experiment. In the sample trial shown here, response button 3 is the correct response.
Fig 7.
Mean response times (A) and net effects (B) in Experiment 3. Error bars and abbreviations as in Fig 3. Note the larger scale on the vertical axis, compared to the Figs 3, 4, and 5.
Fig 8.
Mean response times (A) and net effects (B) in Experiment 4. Error bars and abbreviations as in Fig 3.