Abstract
We all mind wander from time to time, where instead of being focussed on our task, we start thinking about task-unrelated personal events or concerns. In daily life, however, mind wandering is often associated with reduced processing of external information. This is commonly explained by the decoupling hypothesis, which posits that processing of external sensory information is attenuated when attention turns inward. However, it remains unclear whether perceptual decoupling reflects a global, uniform attenuation of sensory processing, or a spatially-specific reduction linked to lateralised attentional mechanisms. In the current, pre-registered study, we used an online signal detection task to assess the impact of mind wandering on perceptual performance in the left and right visual fields. While performing the task, participants periodically reported whether they were mind wandering or on task. Consistent with the decoupling hypothesis, perceptual sensitivity (d′) was significantly reduced on trials during which participants reported mind wandering compared to on-task trials. However, this reduction in sensitivity did not differ between stimuli presented in the left and right visual field. These findings suggest that perceptual decoupling during mind wandering reflects a global attenuation of sensory processing, and that attentional systems involved during mind wandering may be distinct from those associated with slower fluctuations of attentional resources such as reductions in alertness.