Effects of cognitive load on perceived internal and external distraction and their relationship with attentional control

People are assumed to differ in their susceptibility to distraction, depending on their attentional control abilities. Accordingly, susceptibility to internal distraction (in terms of self-generated task-irrelevant thoughts) and to external distraction (in terms of task-irrelevant environmental stimuli) are considered two facets of a global attention-distractibility factor. While it is plausible that these two constructs overlap to some extent, susceptibility to internal and external distraction may nevertheless differ across situations. We thus investigated whether objective changes in external stimulation (manipulated by the presence versus absence of concurrent irrelevant speech) differentially affect perceived external and internal distraction during an ongoing task, and how both distraction types are related to attentional control. In Experiment 1, we used a working-memory task as ongoing task, in Experiment 2, we used a less demanding lexical-decision task. Results of both experiments consistently showed that perceived external distraction was increased whereas perceived internal distraction was decreased under irrelevant speech. Interestingly, attentional control was weakly positively related with perceived external distraction under irrelevant speech conditions. These results highlight that mutual dependencies between internal and external distraction experiences may be more complex than hitherto assumed.