The Stroop Task Redefined: The Multiple-Item Stroop Task

Abstract

A Multiple-Item Stroop Task was created with the goal of providing a sensitive and objective measure of attentional biases. It is a modification of the traditional single-item emotional Stroop task that is intended to assess the extent to which attentional biases distract participants from a colour identification task. The traditional version was viewed as having clinical relevance but that promise has been largely abandoned due to small effect sizes. The goal of this thesis was to investigate whether procedural modifications, informed by theory, might serve to increase the sensitivity of capturing attentional biases using the new Multiple-Item Stroop task. Experiment 1 demonstrated that the standard Stroop effect was observed in both single-item and multiple-item variants, with the magnitude of effect being similar as is consistent with current theories of the Stroop effect, assuming that a single item is sufficient to induce a maximal effect. The emotional Stroop effect was examined but disappointingly found absent in Experiment 2 wherein a small set of emotional words was employed. Subsequently, using a larger stimulus set and more potent taboo words, a significantly enhanced emotional/taboo Stroop effect using the new Multiple-Item paradigm was demonstrated (Experiment 3) and replicated (Experiment 4). Additionally, content relations between the observed effects and independent measures that should be related to attentional capture gave rise to a relatively consistent pattern of relation using the new multiple-item paradigm, at least relative to the traditional single-item variant (also Experiment 4). Taken together, with the use of undergraduates, these empirical results support the use of my proposed new paradigm in capturing attentional biases with healthy individuals and potentially within clinical populations. Limitations and future studies are explored.