Effects of stimulus type on eye movement measures during mindless reading and mindless listening

"Mind wandering" refers to a state when attention is directed to internal thoughts unrelated to the sensations and perceptions of the immediate physical environment. Mind wandering occurs not only in passive situations but also during tasks that require attentional effort such as reading and listening. Despite its ubiquitous nature, the number of studies which examine mind wandering has increased only in the last few decades, particularly due to its subjective nature and spontaneous occurrence. Also, the majority of those studies focused on mind wandering during reading and investigated the differences between "mindless reading" and normal reading. To the best of our knowledge, there are no studies which examine mind wandering in different modalities, the effect of stimulus types on the frequency of mind wandering or contrast the behaviour of eyes under the effect of stimulus types during mind wandering. In this study, we analysed eye movements and pupil size in three conditions, that is, during only reading, only listening and simultaneous reading and listening, in three intervals preceding and following self-reported mind wandering episodes. The results of our study revealed that mind wandering frequency is not affected by stimulus type or cognitive load. The dominance of inner thoughts affects the frequency of mind wandering more than modalities, cognitive load and the demands of the here and now. Analysis of eye-tracking data showed that there are no differences in eye movements and pupil size between mindless and attentive states. However, while fixation duration and pupil size did not vary for modalities and intervals, the number of fixations were significantly higher during only reading than during listening. Thus, our study shows that the absence of any significant differences in fixation count and fixation duration between attentional states shows that a low-level processing of visual-lexical cues continues during mind wandering. These results indicate a sensitivity to visual-lexical stimulus even in absence of conscious effort and an attentional decoupling mechanism in favour of visual-lexical stimulus. Keywords: Attentional decoupling, eye tracking, meta-awareness, mind wandering, mindless listening, mindless reading