Most recent studies depict mind wandering as a costly cognitive failure with relatively few benefits (Mooneyham and Schooler, 2013). This perspective makes sense when mind wandering is observed by a third party and when costs are measured against externally imposed standards such as speed or accuracy of processing, reading fluency or comprehension, sustained attention, and other external metrics.
Daily life often demands that we choose one information stream or the other. For instance, in a decontextualized educational context, or in a cognitive psychology experiment, the ability to concentrate on a task requires silencing the inner chatter. Vice versa, when we would like to dip into our inner stream of consciousness, we must block out our external percepts (Dehaene and Changeux, 2005; Smallwood et al., 2011b; Kam et al., 2013).
However, as Kam et al. (2013) point out, when the executive attention network works in concert with the default mode network to sustain an inner train of thought, selective attention processes are not absent – they just are turned inward to select the most relevant associations and ideas that emerge from episodic memory. This has important implications, because traditional views of selective attention erroneously assume that the main function of the executive attention network is to select relevant stimuli from the external environment for deliberate, conscious processing.
However, these traditional models miss a key feature of human cognition: when working in cooperation with the default mode network, the executive attention network is equally equipped to select relevant episodic associations that can help keep an inner stream of thought both positive and constructive.