Task Format Modulates the Relationship Between Reading Ability and Stroop Interference

Public Significance Statement When compared to poor readers, skilled readers have been previously found to be less prone to word interference when they have to name the color in which a different color-word is printed. This has been interpreted as a result of speedy blocking of the irrelevant word, which is available earlier in better readers. Our experiments show that skilled reading is associated with higher color-naming performance only when items are presented simultaneously in an array, as in previous studies, but not when they are displayed one by one. This format-specific association suggests that the advantage of skilled readers is not due to faster word recognition but perhaps due to efficient simultaneous processing of adjacent items, thereby weakening the theoretical claim of a direct connection between individual word recognition speed and interference from words to color naming. Previous research has shown that Stroop interference and reading ability are negatively related, with higher reading skills associated with less interference. A direct link between interference and the speed of inhibition of the task-irrelevant dimension (i.e., word) has been proposed to explain this relationship. If that were the case then it should apply regardless of the format of the Stroop task, that is, whether stimuli are presented simultaneously (multi-item version) or individually (single-item version). Here we examine data from six experiments using single-item and multi-item Stroop tasks and their relationship to reading measures. Our results indicate that reading performance is primarily related to the multi-item version of the Stroop task and not to the single-item version. These findings question the direct link between inhibition and interference as an interpretation of the reading-interference relationship. We argue that cascaded processing of successive items, and the ability to monitor and control this process, is the cognitive mechanism regulating the relationship between reading and interference. Therefore, we propose that the link between Stroop interference and reading is indirect, and their relationship is determined by the efficiency in temporally overlapping processing of adjacent items.