Dynamical contributions of reconfiguration and internal shielding to attentional flexibility: evidence from a drift diffusion model

Attentional flexibility, the ability to switch between external and internal information, is characterized by an internal shielding benefit, as reflected behaviorally by an asymmetric switch cost in the Switching Attention Task (SAT). However, besides internal shielding, other processes such as reconfiguration (i.e., a preparatory attentional component) might also contribute to attentional flexibility. To investigate the underlying mechanism, we ran three behavioral experiments based on the SAT and used a drift diffusion model (DDM) enabling to disentangle reconfiguration from shielding, which are reflected in the non-decision time and drift rate, respectively. In Experiment 1, we manipulated reconfiguration by varying the cue-stimulus interval (CSI; short, intermediate, or long). Internal shielding, which was visible only at the intermediate CSI, was impaired at both the short and long ones, suggesting that modulating preparation time affects internal shielding during attentional flexibility. In Experiments 2 and 3, we reduced the stimulus set size either proportionately or disproportionately for external and internal attention to vary working-memory load and hence internal shielding. With a proportionate reduction of the two set sizes, internal shielding decreased. Moreover, external attention showed enhanced shielding when a smaller set size was used for it compared to internal attention, whereas reconfiguration prevailed when internal attention was less heavily taxed compared to external attention. Together, these findings suggest that both reconfiguration and internal shielding contribute to attentional flexibility, but their weights vary depending on the strength of the competition between internal and external attention.