Attentional Flexibility is Imbalanced: Asymmetric Cost for Switches between External and Internal Attention

Whereas the effects of attention switches occurring within perception or memory are relatively well understood, much less is known about switches of attention between them. We discuss the methodological limitations of initial research on this topic, which was never integrated with the broader cognitive literature. On the basis of this discussion, we present here a new paradigm, in which participants performed a simple probe-to-target matching task where targets were either perceived on screen or retrieved from memory. Across successive trials, repetitions or alternations (in both directions) between these two conditions were created, and eventually compared to each other. In line with our prediction, derived from the assumption of a top-down control mechanism, we found a cost for switching between external and internal attention in Experiment 1. Furthermore, this switch cost was asymmetric, being substantially larger when switching from (external) perception to (internal) memory than the other way around. In Experiments 2-4, we ruled out an imbalance in practice, learning, and preparation as confounds for this asymmetry. We propose that switches of attention between internal and external information are underpinned by a supervisory attention control mechanism, and that this asymmetry can be explained in terms of priming, associative interference or memory retrieval.