Inhibitory deficits in trait anxiety: increased stimulus-based or response-based interference?

Trait anxiety is associated with an impaired ability to inhibit task-irrelevant distractions. However, distractions may cause conflict at multiple stages within the information-processing stream, which may be resolved by different subsystems, depending on the type of conflict. Here, we contrasted two forms of conflict that have been distinguished in the literature: stimulus-stimulus (SS) versus stimulus-response (SR) competition. Across two experiments, participants completed a Stroop-like task that included distractor color words that could be either a different color promoting the same response as the target (SS interference) or a different color promoting a different response (SR interference). In line with previous studies, anxiety increased overall task-irrelevant distraction, measured by incongruent versus congruent reaction times. Importantly, this increase was driven solely by SR conflict, with no evidence of group differences in SS interference, despite clear within-subjects costs. These results clarify that trait anxiety may modulate inhibitory responses primarily by disrupting the resolution of response competition, while having little effect on stimulus conflict. Additionally, the results highlight the utility of distinguishing forms of conflict resolution, particularly in individual-difference approaches in which inhibition is impaired in a variety of clinical and nonclinical populations.