Working memory load and Stroop interference effect

Although the effect of working memory (WM) load on the magnitude of distractor interference has been studied extensively, a common characteristic in prior research is that the target and distractors belong to different objects. The present experiments investigate the effect of WM load on distractor interference when the relevant and irrelevant information is part of the same object. In two experiments, participants saw stimulus displays that consisted of a memory set followed by a Stroop color stimulus. The tasks were to respond to the color of the stimulus first and then to a memory probe. The principal manipulations were the relationship between the color and meaning of the Stroop stimulus (neutral vs. incongruent) and the level of WM load (high vs. low). The results show that WM load had little effect on the magnitude of Stroop interference. These results were consistent with previous research which shows that WM load plays a limited role in the efficiency of selective attention when the extent of attentional focus was held constant across different WM load conditions. They also emphasize the importance of stimulus structure in understanding selective attention in general, and distractor processing in particular.