ADHD, Mind Wandering and Cycling Accidents

Our neuroscience experts review the news...
20 December 2018

Interview with 

Duncan Astle, Cambridge University; Helen Keyes, Anglia Ruskin University


Brain schematic


Cambridge University cognitive neuroscientist Duncan Astle and perceptual psychologist Helen Keyes from Anglia Ruskin University sifted through the latest neuroscience news, and told Katie Haylor what caught thier eyes...

Duncan - The authors are really interested in attention deficit hyperactivity disorder or A.D.H.D. One of the symptoms of A.D.H.D is increased prevalence of mind wandering among other symptoms but of course we all know that you don’t have to have a diagnosis of A.D.H.D to suffer from mind wandering. It’s something that we all encounter.

They were really interested in understanding the neural mechanisms behind mind wandering and how that might interact with cognitive skills. So they got 185 young adults. They put them in an MRI scan and they made them perform a task called an N-back task. It's a very simple short term memory task and periodically they would stop the task and they had a series of questions about how well concentrated the individuals were, what they were thinking about, how hard they were working on the task, what their minds were on. They had quite detailed information about mind wandering and these were interspersed throughout the task. And at the end of the scanning session they also rated the subjects for their A.D.H.D like symptoms.

And what they found really interestingly was that those who had high ratings of these symptoms firstly they would be more likely to mind wander. That tells us that indeed it is the case that these things vary naturally throughout the population even in people who don’t have a diagnosis, and they found that those people who did mind wander more, they performed more poorly on visual memory task on the N-back task and then when they looked at the neuro-imaging data they found that areas of the brain involved in what we call cognitive control so areas in the frontal lobe and areas in the parietal lobe, the connectivity between these areas and sensory areas like visual cortex would drop out periodically. And in those moments, subjects are more likely to mind wander and that's when their cognitive performance would drop.

It's a really nice demonstration of how you can link these sort of higher order symptoms that we all encounter and that are very common in kids with A.D.H.D. Linking it to a neural mechanism, and then there's a cognitive outcome which in this case is visual short term memory.

Katie - What would you recommend somebody would take away from this study?

Duncan - Firstly is to say the mind wandering that we experience as a sort of a very higher order phenomena that happens all the time, actually has some really basic underlying neurobiology to it that we're starting to understand. Secondly that it happens to lots of people. And thirdly that it happens to some people an awful lot and that's because this neuro biological mechanism is more likely to kick in in those individuals.

Katie - Helen, any comments?

Helen - Yes so you said they noticed a correlation between instances of mind wandering and the dropping of the connection in the brain areas. So which drove which?

Duncan - It’s very hard to say. The way that I would think about it is that it's one process that we can analyse at two different levels so we can analyse it at the kind of experiential level that describes the experience of switching off and the zoning out. And then at the same time there's underlying neural correlate can be demonstrated. Now those two things go hand in hand. There may be some previous mechanism that causes both but I think these things are just sort of two halves of the same coin.

Katie - Thank you very much. So Helen you've been looking into a paper about whether or not we should be wearing helmets. Particularly pertinent for people who live in Cambridge these are cycling helmets. What were this group trying to find out?

Helen - They were trying to find out whether wearing a helmet would make you take slightly more risks and they were measuring this by looking at how you perceived distance between you and threatening objects or you and non-threatening objects.

Katie - What were these threatening and non-threatening objects?

Helen - So in a very realistic setting, they used pictures of a tiger or shark as you would commonly encounter in Cambridge! That was the threatening stimuli, or non threatening stimuli such as rabbits, mice, horses, things like that.

Katie - OK. So this is a lab study trying to replicate behavior perception when you wear a helmet compared to when you don’t when you’re cycling. What did they find?

Helen - So they found that if you wear a helmet compared to if you wear a baseball cap, you did risk compensate. So for objects that you perceived to be non-threatening such as horses and rabbits, you actually overestimated the distance between you and them, you thought they were further away which suggests wearing a helmet made you feel safer, you risk compensated.

Some good news for helmet wearers is that this didn't apply for threatening objects, so when there was a threatening stimulus in front of you you re-adjusted your risk level, it overrode that risk compensation behaviour and you saw the threatening object as close to you. Similar to people in baseball caps. So people in baseball caps saw threatening and non-threatening objects as quite close to them. People with helmets saw threatening objects as close but safer objects as further away, they overestimated that distance.

Katie - So what should people take away from this with regard to their cycling behaviour? Because I certainly would always wear a helmet!

Helen - So it does add to the debate in an interesting way because it suggests that wearing a helmet can be positive. The general worry in wearing a helmet is that we recalculate the level of risk, feeling safer and therefore we take more risks. So this study is saying, actually, if a threatening situation arises you will suddenly recalculate your risk taking into account that threat and you will perceive things safely. So the presence of a threat will override that overconfidence is what this paper is saying.

However it also suggests that if you’re not expecting a threat, so if you’re cycling along feeling quite safe, you will be a little bit cocky and take those risky behaviours. So they’re saying you overestimate distance,  you take more risks if you feel quite safe as a cyclist wearing a helmet. Whereas you don’t do that when you’re not wearing a helmet.

So you can take from that what you will. On the one hand it's comforting to know if you wear a helmet you will recalculate your risk perception if a threat is present but if you don’t perceive that threat you could be engaging in risk taking behaviours that you wouldn't otherwise engage in.

Katie - Generally, how much evidence is there to suggest wearing a helmet can put us at risk?

Helen - There is quite a lot of evidence coming from road cyclists and drivers. So we know that drivers will give cyclists less space when they're overtaking, if the cyclist is wearing a helmet and we know from numerous studies that cyclists engage in much more aggressive cycling much more risk taking behaviour when they're wearing a helmet compared to when they're not.

Katie - But is it also fair to say that we do know a cycle helmet can make a vital difference if you are involved in a crash?

Helen - If you are in a collision, without a doubt, you need to be wearing your helmet. Your wearing a helmet is going to significantly reduce the chance of brain injury. The same is also true though for pedestrians and car drivers, so if you are a pedestrian perhaps you should also be wearing a helmet. And interestingly on a numbers level, if you are in a car accident let's say you're a driver compared to a cyclist. If you're both in a collision, the cyclist is going to need the helmet more than you. But on a pure numbers level the amount of people that are in car collisions every year. If all drivers mandatorily wore helmets we would decrease the level of brain injury more than if we ask cyclists to wear helmets, because it's just fewer cyclists and we would probably think it would be a bit mad to start saying drivers should wear helmets.

Katie - Duncan, do you cycle around Cambridge?

Duncan - I do, and I do wear my helmet. I'd like to think I am reasonably cautious with my helmet on. I guess it's one of those things were there are probably massive individual differences. There are some people who presumably are such cautious cyclists they'll be cautious regardless of whether they wore a helmet. Whereas there are presumably some people who share a big helmet effect and cycle very differently.

Helen - I do insist that my children wear helmets, so I'm a bit of a hypocrite.


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