When we think of demographics that are easily distracted, we tend to think of younger generations, people on their phones over dinner or texting while driving, or only listening to you with one ear while they listen to their ipod with the other. But when we’re talking about cognitive tasks like working memory, the ability to work without distractions is actually highest when you’re younger, and decreases with age. Working memory is the ability to store bits of information and manipulate them over a short period of time. How long the working memory lasts for depends on what you’re trying to remember (say, a string of words that makes sense over a string of numbers that doesn’t), the amount of information you’re trying to process, and…on how distracted you are.
So today’s post for you is something that…oooh, look, something shiny!!!
…
…where was I?
Right.
Clapp et al. “Deļ¬cit in switching between functional brain networks underlies the impact of multitasking on working memory in older adults” PNAS, 2011.
When we talk about distractions in the context of working memory, we’re not just talking about the kind of distractions made from sighting something like Snooki or something else that is merely distracting. We’re also talking about the kind of interruptions that occur when you’re trying NOT to ignore them, but attend to them. These are the interruptions that characterize multitasking. We usually refer to these are “interruptors” which are different from distractions. Distractions are things you’d rather ignore, while interruptions are things that you are trying to integrate into your current working memory tasks.
Note: As a real life example of this, Sci is writing this post while looking at her Twitter. Normally, Twitter would just be a distractor here, something that she needs to ignore to get her post done. But tonight Twitter is blowing up with the News that Osama Bin Laden is dead. This is information that I want to keep an eye on (obviously), and so a former distractor has become an interroptor as I try to multitask. Needless to say, it’s not going very well. Continuing this one in the morning.
From the AM:
Since interruptions are things that you try to incorporate when you multitask, it has become an interesting focus of some scientists to see how the ability to incorporate interruptions into working memory, and therefore how to multitask, changes with age and experience. Thus far, we know that as we age, we become less adept at multitasking, and have a harder time tuning out distractions and incorporating interruptions. This can be important, as people are now working later and later in life in jobs which require things like multitasking and handling large amounts of distractions.
While we know that the ability to multitask (as related to distractions and working memory) decreases with age, we don’t know WHY this occurs. To test this, the authors of this study compared a working memory task between young adults and older adults. The people were put in an fMRI (functional magnetic resonance imaging machine for detection of the brain anatomy and where oxygen usage is going in the brain). While they were in the scanner, they had to perform a task. The task was to look at and remember a particular detailed nature scene for 14 seconds, and then to tell whether it matched a newly presented scene. During the delay between the first scene and the second, the participants could get a distractor, a face presented in the middle of the trial, and an interruptor, a face presented in the trial that they ALSO had to remember, as well as remembering the nature scene. The authors of the study could then measure how well working memory was going by how well the participants were able to match a scene after a distraction or an interruption.
They found that the older adults (as you might expect) did ok in the presence of distractions, they didn’t do as well at the task, but neither did the younger adults. But when the older adults were asked to REMEMBER the face, making it an interruption instead of a distraction (and requiring multitasking), they did significantly worse than the younger adults, showing that multitasking doesn’t go as well.
When the participants were looked at with fMRI as they did the task, they looked specifically at areas known as the fusiform face area (FFA), the middle frontal gyrus (MFG), and the parahippocampal place area (PPA). The FFA is selectively responsive for faces (the distracting stimuli they were using), and is also regulated by attentional processes. The MFG and the PPA, on the other hand, are areas that are known to show activity TOGETHER in the middle of a working memory task. This can then be interrupted when there is a distractor. So by looking at the FFA, the authors could study whether the older people were reacting merely to the presence of the faces differently, and how much they were processing that information, while looking at the MFG and PPA could help to determine how distracted they were getting during working memory.
Above you can see the results from the FFA. When older adults were compared to younger adults, they processed the faces just as much, showing just as much activity in the FFA, and showed the same correlations in the working memory task. So this rules OUT the idea that maybe the older adults were processing the interruptors MORE than the younger adults.
Here you can see the activity in the PPA and the MFG (PPA is on the top right and MFG is on the bottom right), during the tasks. With no interferance (NI), you can see that younger and older adults did the same in both areas. The same goes for the Distractor stimulus (DS). But when they got the interference stimulus (the face they had to REMEMBER), both young and old participants had a decrease in PPA activity and an increase in MFG activity. The authors think that this represents a disconnection between the two areas. What stands out though, is how LONG the disconnection lasted. You can see the older adults took longer to recover than the younger ones did.
So the total findings of the study show that while younger and older adults got distracted at the same rate, and processed at the same rate, the older adults took longer to RECOVER from the distraction and get back to the task, resulting in decreases in multitasking ability. In other words, they have a slower switch than younger people do. This isn’t necessarily a bad thing, it’s just a natural decrease with age, but it could be one way to explain why older people can’t always multitask like younger people do.
Of course there are issues with the study. I’m not sure than an increase in activity in one area and a decrease in another necessarily represented a DISCONNECT of those two areas. And of course, other areas of the brain may be involved, for example areas of the prefrontal cortex that are involved in damping down our processing of irrelevant stimuli. They also found that the PPA activity in older adults was shifted slightly compared to younger adults, and that might be one of the reasons that the processing is different.
I’d also be interested to see a different angle on this study: how do these connections work in people who multitask often, vs those who multitask relatively rarely? Anyone know a paper on this? I’d be glad to cover it!
Clapp, W., Rubens, M., Sabharwal, J., & Gazzaley, A. (2011). Deficit in switching between functional brain networks underlies the impact of multitasking on working memory in older adults Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1015297108
