The Stroop-like Task

The Stroop-like Task is illustrated by a choice reaction time task that uses color-word stimuli written in colored ink, the ink  is usually the relevant stimulus, but assigns them to key-press responses. As a result, there is dimensional overlap between the irrelevant and the relevant stimulus, but no dimensional overlap with the responses. In the dimensional overlap taxonomy, it is considered a Type 4 task. Other Type 4 tasks include the Flanker task and Cross-Modal tasks.

A number of researchers have explored performance in Stroop-like tasks (e.g. Hommel, 1998, exp. 1; Kahneman & Henick, 1981; Keele, 1972; Kornblum, 1994; Kornblum et al., 1999; Simon & Berbaum, 1990; Simon, Paullin, Overmyer & Berbaum, 1985, exp. 2). Typically, subjects are told to press a left key or a right key depending on the color of the stimulus. The color word is irrelevant, but can be either consistent (e.g. “blue” written in blue ink) or inconsistent (e.g. “green” written in blue ink) with the color. Responses are faster and more accurate for consistent stimuli than for inconsistent stimuli.

Stroop-like task

Unlike in the Flanker task, where the relevant and irrelevant stimuli are perceptually similar, this task only contains conceptual overlap between the two stimulus sets: color and color words are only linked through a learned symbolic association.

This task is called “Stroop-like” because the stimuli used in the task are the same as the stimuli first used by Stroop (1935) for the Stroop task. However, these tasks are different from actual Stroop tasks, because in Stroop tasks there is also overlap between the stimulus dimensions and the response dimension. You will sometimes see papers describing these tasks as “Stroop tasks”, disregarding the fact that the responses in these tasks have no overlap with color. According to Dimensional Overlap model, this difference is critical: cognitive processing in Stroop-like tasks and Stroop tasks is fundamentally different, based on the presence or absence of dimensional overlap with the response dimension.

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