Stroop-type interference: Congruity effects in color naming with typewritten responses.

Abstract

Four experiments examined the Stroop effect with typewritten responses. Experiment 1 compared vocal, arbitrary-keypress, and typewritten responses and found the largest Stroop effect for typewritten responses. The effect appeared in the latency to type the first keystroke and not in the duration of the typing response. Experiment 2 compared normal (name the color) and reverse (name the word) Stroop effects with typewritten responses and found that the normal Stroop effect was much larger than the reverse Stroop effect Experiment 3 compared typing the entire color name with typing its first letter and found equivalent Stroop effects in the 2 conditions. Experiment 4 varied the relative frequency of congruent and incongruent trials and found that the typewritten Stroop effect was larger when congruent trials outnumbered incongruent trials. The results are related to theories of the Stroop effect and theories of language production. Stroop (1935) found that subjects took longer to name the color of the ink in which color words were written than to name the color of the ink in which control stimuli were written. This so-called Stroop effect has been replicated hundreds of times, and current theories are still striving to explain it (for a review, see MacLeod, 1991). An important issue, theoretically and empirically, concerns the effect of response modality in the Stroop task. Stroop's investigation and the majority of the replications required vocal responses; subjects said the color names out loud. Most of the other replications used arbitrary-keypress responses; subjects pressed keys that were associated with color names (e.g., Keele, 1972; Pritchatt, 1968; Sugg & McDonald, 1994; Virzi & Egeth, 1985). The Stroop effect is found with both response modalities. Studies that compared response modalities often found a stronger Stroop effect with vocal responses than with arbitrary keypresses (Logan, Zbrodoff, & Williamson, 1984; Majeres, 1974; McClain, 1983; Melara & Mounts, 1993; Neill, 1977; Redding & Gerjets, 1977; Simon & Sudalaimuthu, 1979; White, 1969), though some found no difference between response modalities in the magnitude of the effect (Roe, Wilsoncroft, & Griffiths, 1980). Response modality effects bear on important issues in the Stroop literature, including the factors responsible for the Stroop effect, the role of automaticity and modularity in the