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MIND WANDERING AND WORKING MEMORY
Working Memory: modulating Task-Unrelated Thoughts and their subsequent effects on Task Performance
DimaObari
American University of Beirut
Mind Wandering, also know as task-unrelated thoughts, is still a developing topic in psychology. It is defined as the shift in attention from the task being performed to thoughts that are irrelevant to the task. Typically, half our daily life is spent mind wandering (Levinson, Smallwood & Davidson, 2012). Recent studies have sought to explain individual differences in mind wandering propensity in terms of differences in working memory capacity.In fact, extensive research has undertaken the study of the nature of the relationship between working memory capacity and mind wandering. Two main, conflicting approaches are of importance to us here. While the resource-demanding view proposes that working memory resources are required for the maintenance of task-unrelated thoughts (Smallwood, 2010), the control failure x concerns view maintains that mind wandering in fact represents a failure of working memory to inhibit task-related thoughts(McVay & Kane, 2012). For our purposes, we will first proceed by integrating both approaches along with their opposing findings, by taking a third factor into account: task demands. Then we will conclude with the effects of mind wandering on the processing of external stimuli, both relevant and irrelevant to task performance.
According to Smallwood (2010), mind wandering is a phenomenon that albeit is initiated in a spontaneous manner, relies on working memory resources. Thus, one would expect that the propensity to mind wander should vary according to the availability of those resources. That is, when the task performed places a high demand on cognitive resources, mind wandering should decrease. Indeed, Forster & Lavie(2009) manipulated perceptual load in a series of perceptual search tasks by changing the number of search items. They found that, as the perceptual load increased, participants reported less task unrelated thoughts, a finding that was consistent across all four conducted experiments. Furthermore, in an experiment requiring the generation of random numbers, participants produced significantly less random sequences of numbers following stimulus-independent thoughts (SITs) compared to no-thoughts (NTs). This suggests that when mind wandering did occur, it caused a decrease in performance as a result of the sharing of cognitive resources (Teasdale, et al., 1995).
Interestingly, in another experiment, by Teasdale, Proctor, Lloyd & Baddeley (1993), this negative correlation between mind wandering and performance was not found when the task did not significantly tax working memory. Indeed, when participants were required to remember a single digit rather than five,the experiencing of task-unrelated thoughts,though associated with a lower level of awareness of the digits, did not interfere with memory performance, which was perfect on all trials. Moreover, Mason et al. (2007) found that mind wandering increased during performance on practiced blocks of working memory tasks, as compared to novel blocks. Thus they concluded that practice resulted in a decrease in processing demands, which allowed more resources to be allocated to mind wandering.
So far, the evidence reviewed was in favor of a view of working memory that facilitates mind wandering by providing it with the required resources, when the latter are available. However, McVay & Kane (2010) proposed an alternative explanation for the decrease in mind wandering associated with high-demanding tasks. According to them, when the task necessitates cognitive resources, working memory inhibits task-unrelated thoughts by focusing attention on the current task. Thus, mind wandering represents a failure of attention control and, consequently, a limitation of working memory capacity. Their argument is based on the findings that individuals with higher working memory capacity, who, according to the resource-demanding view, should have more resources to mind wander,actually reported less task-unrelated thoughts (McVay& Kane, 2009).
This argument is in accordance with the control failure x concerns approach, where mind wanderingpropensity is determinedby the executive control system’s efficiency in dealing with interference. This system consists in two main components, each of which was associated with different brain regions. On one hand, proactive control is necessary for maintaining on-task thought throughout the task and is accompanied by an increase in activity in the dorsal lateral prefrontal cortex. On the other hand, reactive control is introduced when proactive control fails, as to suppress any off-task thought that has surfaced in response to a cue and that may cause a conflict with on-task thought. It is associated with higher activation of the anterior cingulated cortex. This division was based on a neuroimaging study that revealed a double dissociation between the two components (MacDonald, Cohen, Stenger & Carter, 2000). In another study involving a stroop task, Kane & Engle (2003) examined how individual variation in working memory capacity affected attention control. They found, consistent with the executive attention model, that individuals with lower working memory capacity had more difficulty with incongruent trials (for example, the word GREEN written in red ink), relative to those with higher working memory capacity. However, they were faster on congruent trials (GREEN written in green ink). This shows that they were reading the words instead of reporting the color of the ink, as requested from them, thus revealing a problem with goal maintenance (a type of proactive control). Additionally, they remained slower on incongruent tasks when the goal was made accessible to aid with proactive control, suggesting also a problem with resolving the competition between the color’s written name and the color of the ink (a type of reactive control).
This view also takes into account the current concerns of the participants, cued by the context in which the task is being performed. Indeed, Antrobus, Singer & Greenberg (1966) tested the assumption that task-unrelated thoughts are generated spontaneously when individuals are presented with information that does not match the expectations they have of the future. For that matter, they presented the experimental group with a false broadcast stating that communist China has announced war to the United States, before they had them complete a simple signal detection task. Relative to the control group who did not hear the broadcast, participants experienced more spontaneous, off-task thoughts during the task. In another study, Klos & Singer (1981) measured adolescents’ history of interpersonal stress with a parent, and had them simulate either a coercive, or a collaborative confrontation with that parent. They then measured their levels of affect arousal and the frequency of repetitive thoughts they experienced afterwards. They found that, when knowledge of the person’s stress history was added to knowledge of the situation, this led to a significantly better prediction of both affective and cognitive responses. Indeed, participants with a long-standing history of interpersonal stress who simulated the coercive confrontation experienced more repetitive thoughts, as they had to cope with both internal (stress history) and external (simulation of the confrontation) sources of affect. Thus repetitive cognition is determined not only by situational cues, but also by self-generated determinants pertaining to the participants’ past, a finding that is supported by the control failure x concerns approach to mind wandering. Finally, Giambra (1989) found an inverse relationship between age and task-unrelated thoughts, a finding that was consistent across all of the five experiments he had conducted. This could be explained by the hypothesis that older adults have fewer concerns, and thus are less subject to internal sources of interference. Carlton, Klinger & Perlmutter (1988) did indeed obtain a correlation between concerns and mind wandering in older adults. Indeed, in their study, older participants reported a lower number of current concerns, and engaged in fewer task-unrelated thoughts during task performance, as compared to college students.
Thus far, we have reviewed two conflicting approaches of mind wandering; one supports that mind wandering necessitates working memory resources (resource-demanding view), while the other attributes an inhibitory influence to working memory over task-unrelated thoughts (control failure x concerns view). A more recent study by Levinson, Smallwood & Davidson (2012) attempted to integrate both models by having participants complete tasks that placed minimal demands on cognitive resources. For that mater, they had participants complete a low-load visual task and a breath-awareness task, and found that, consistent with the resource-demanding view, participants with greater working memory capacity mind wandered more during both tasks. However, they interpreted their findings by attributing a dual role to working memory, which, they argued, modulates mind wandering according to the situational demands created by the task being performed. However, do these objective laboratory findings generalize to more natural settings? In an experience sampling method of daily life, Kane, Brown, Little & Sylvia (2007) found that while, individuals with higher memory capacity experience more off-task thoughts when they were not trying to concentrate, their mind wandering decreased when they deliberately focused attention on the task, which is in accordance with laboratory research results.
We will now turn to a third approach, the decoupling hypothesis, which maintains that, contrary to the control failure x concerns view, mind wandering does not represent an instance of failure to maintain attention on task-relevant stimuli, but consists in fact in one’s attention being turned away from all external stimuli, toward one’s internal thoughts. Perhaps the best supporting evidence of this view comes form an experiment conducted by Barron, Singer & Greensberg (2012), in which event-related potentials in relevant brain areas where measured while participants conducted an oddball task, thus allowing an ongoing assessment of attention. Two components, P3a and P3b were studied; variation in the amplitude of theP3a component indicated the level of external distraction, while variation in the P3b component was used as an index of the attention allocated to task relevant stimuli. These measures were followed by retrospective self-reports that allowed to assess the frequency of task-unrelated thoughts and thus to separate participants into a low and a high task-unrelated thoughts groups. The experimenters observed that the group that was higher in task-unrelated thoughts had lower amplitudes for both the P3a and P3b components. Thus they concluded that mind wandering involves a decrease in the processing of both task-relevant and task-irrelevant thoughts. The decoupling hypothesis thus suggests that mind wandering consists in the decoupling of attention from all external, perceptual stimuli, regardless of their relevance. It thus insulates the internal train of thoughts in order to prevent interference form external perceptual events.
All in all, when the tax being performed places high demands on cognitive processes, working memory prevents task-unrelated thoughts from surfacing by the means of proactive and reactive processes, thus focusing attention on the task being performed. However, when the task is more permissive for mind wandering to occur, working memory not only facilitates task-unrelated thoughts, but also protects them from interference by limiting the processing of all external stimuli, regardless of relevance.
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