Why are older people less prone to mind wandering?

Invite a group of older participants to a psychology laboratory to engage in computer-based mental tasks, and you'll find that their minds wander less often than the minds of young adults. This has been established many times by studies that interrupt participants mid-task to ask them what they're thinking about.

At first, the finding appears to be a conundrum. Older adults typically perform worse on cognitive tasks than younger people, and ageing is usually thought to have an adverse effect on concentration. So, if anything, you'd think mind wandering would increase with age.

In fact, the age-related decrease in mind wandering is consistent with an influential theory. This states that we mind wander off a primary task when we have mental capacity to spare, such as when that task is easy or well-practised. By this account, it makes sense that older adults mind wander less because they have fewer attentional resources to spare.

However, not all experts accept this resource-based theory. Jennifer McVay and her colleagues propose an opposite account of mind wandering. They think we mind wander when we lose attentional control and our focus turns away from the task toward other issues of concern. They point to research showing that the performance of young and old is harmed equally by mind wandering, a fact that doesn't make sense in terms of mind wandering only occurring when the mind has spare capacity.

In a new study, McVay and her colleagues tested the idea that past research has underestimated how often older adults mind wander. They think this mind wandering tends to be toward performance-related concerns that previous research has probably miscategorised as on-task focus. Older adults are more anxious about doing well, McVay says, and so a lot of their mid-task thoughts are about their performance, which is not the same as being focused on the actual task.

An initial study involved 108 young adults (aged 18-28) and 99 older adults (aged 60 to 75) completing two computer tasks. One was a test of inhibitory control; the other a test of sustained vigilance. During these tasks, the participants were periodically prompted to say what they were thinking about. McVay's crucial innovation was to present participants with a response category that related to performance concerns, alongside the categories of completely off-topic thoughts or pure task focus.

As predicted, the older adults reported more thoughts that were about task-related concerns (thoughts that may have been mis-categorised by earlier research as task focus). But even taking these extra performance-related thoughts into account, the older adults still mind wandered far less often than the younger adults (31 per cent vs. 48 per cent). Or, put differently, the older adults still spent more time focused on the actual tasks.

A second study with a new batch of older and younger participants was similar but this time the task was harder - requiring participants to report whenever the current item in a stream of digits or letters was the same as one that occurred one or two positions previously. The results were similar - older adults reported more task-related concerns for the harder version of this task, but altogether they again actually had fewer moments of lost focus compared with younger participants.

As in previous research, instances of mind wandering were equally harmful to the performance of young and old participants, which McVay's team reiterated was inconsistent with the idea that mind wandering occurs when spare capacity is available. The fact that older adults found the mental capacity to dwell on performance-related concerns more than young people also seems to count against the reserve capacity explanation for why they mind wander less.

So where does this leave us? McVay's group stand by their theory that mind wandering reflects a loss of attentional focus combined with a shift of attention to other concerns. These non-task concerns vary in their salience depending on the context. McVay's team believe that in a laboratory environment older adults are less distracted by off-task concerns, such as their relationships and well-being, and that's why they mind wander less in these kinds of experiments:

"the college campus setting," they explained, "with bustling hallways, high-tech computer workstations, and young student experimenters, is more likely related to the goals and current concerns of the undergraduate population, and so the typical context for aging studies is less likely to trigger current-concern-related TUTs [task unrelated thoughts] in older subjects."

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  McVay, J., Meier, M., Touron, D., and Kane, M. (2013). Aging ebbs the flow of thought: Adult age differences in mind wandering, executive control, and self-evaluation Acta Psychologica, 142 (1), 136-147 DOI: 10.1016/j.actpsy.2012.11.006

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.