Going Off Task: Exploring Mind Wandering in the Aging Brain

We’ve all experienced it – reading some pages in a book when your mind starts to drift and then realizing that you missed a key point and have to go back and reread the same page. The experience of mind wandering appears throughout our daily lives, whether reading, driving home from work, or even when in conversation with someone. Older adults report less mind wandering as they age, yet, counterintuitively, often perform worse on cognitive control tasks.

New work, published in the Journal of Cognitive Neuroscience, finds that even though older adults report less mind wandering than younger adults, the neural impacts of that mind wandering are similar across both age groups. The work challenges the idea that any changes in cognition in older adults must lead to impaired performance. 

“As aging researchers, I think we often fall into the trap of framing cognitive changes that occur with age as deficits, but our work is one of many that I think paints a pretty positive image of aging,” says Sarah Henderson, a grad student at Brock University (Ontario) in the Campbell Neurocognitive Aging Lab. “It appears that older adults are actually quite good at maintaining focus on the task at hand and using their motivation to perform to their advantage.” 

I spoke with Henderson about the new paper and its broader significance in aging research.

CNS: How did you become personally interested in studying mind wandering?

Henderson: This work was a collaborative effort and I really began thinking about mind wandering because of my co-author and former lab mate, Dr. Dawn Ryan.  I was hoping to gain some insight about how older and younger adults may differ in what they are really thinking about while they are completing our tasks and how we could use that information to shape how we think about attention. 

If you’ve ever completed a cognitive task in a lab, you probably know that you don’t really maintain focus on your task for the whole time. I know I certainly don’t. Despite your best efforts, you probably feel like you can’t help but drift off to thoughts about what you need to do later or thinking about how you’re doing on the task. We know older adults typically differ in their ability to maintain attention and their motivation to perform well on our task, which can affect how someone’s mind wanders. So since our lab is interested in interactions between attention and memory in aging, we had always had some questions about whether the age differences (or the lack thereof) that we observed in many of our cognitive tasks may be influenced by differences in what people were really thinking about while completing our, usually boring, tasks.

CNS: What specific new insights were you seeking?

Henderson: In this paper we had two major goals. Firstly, because there may be age differences in how accurately someone self-reports their mind wandering, we wanted to test whether we could use more implicit measures to determine when someone was focused on the task vs. when they were mind wandering. This would be great both because it would allow us to compare implicit and explicit measures of mind wandering, and importantly, would let us look at the effect of mind wandering on a trial by trial basis throughout the task, not just in the few seconds before we ask them what they were thinking about. 

Secondly, we wanted to see whether the impact of mind wandering was similar across age groups. If the content or frequency of mind wandering differs with age, we might also expect that the way it influences stimulus processing might differ with age. So we used EEG to look at how being on- vs. off-task would alter the visual and cognitive processing of our task stimuli.

CNS: What were you most excited to find? 

Henderson: I was most excited to see that in our study, the effects of mind wandering were actually pretty similar across age groups. I think we’re inclined to think that older adults must show some cognitive deficits compared to our younger reference groups, so it could be tempting to assume that if they’re mind wandering less, it must impair them more when it does happen. Our behavioral results were consistent with many studies showing that older adults mind wander less, but when we looked at the EEG data, we found that in both age groups, people have relatively normal early visual processing, but the later cognitive processing of stimuli was impaired when off-task. This is also interesting because it really falls in line with the anecdotal experience of mind wandering as feeling like you’ve gone through the motions of the task but not really processed incoming information [like in the reading example]. 

CNS: How were you able to implicitly measure the mind wandering?

Henderson: Using the implicit measures of mind wandering was something we were really excited about. We found that we could use reaction time variability to sort trials into periods of being on- vs. off-task, and these more automatically sorted trials corresponded with what people explicitly reported they had been thinking about. This is great for neuroimaging studies, which typically require many trials, as it lets us look at the whole task instead of just the few trials right before someone reports their thoughts. Explicitly asking someone what they’re thinking about is a great way to understand the subjective experience and the content of mind wandering, but using this implicit, reaction-time based measure was great for our neuroimaging approach.

CNS: Are there any translational aspects to this work?

Henderson: We didn’t directly assess why the groups differed in mind wandering frequency in our work, but others have argued that motivation plays a large role in determining how frequently individuals mind wander on a particular task. This is very much in line with our observation that older adults mind wander less in lab-based tasks where they are typically more motivated to perform well compared to younger adults. So I think this speaks to the importance of motivation in maintaining focus on a task.

CNS: What’s next for this line of work? 

Henderson: In our lab, we continue to be interested in the interactions between attention and memory. Some upcoming work from our lab is looking to test how fluctuations in attention shape the way we bind information together in memory. 

-Lisa M.P. Munoz