Apr 18 2011

Attention and Memory

By now most readers have likely seen the famous basketball-passing video. But if you have not, check it out here before reading further. It’s a fun test, but will be spoiled by the discussion here.

The phenomenon demonstrated by the video is called inattentional blindness (I have also seen attentional blindness and inattention blindness). It reflects the fact that we have a finite capacity to process information. We cannot attend to all the sensory information coming from our environment at the same time, let alone do that and attend to other cognitive tasks as well, like solving a math problem. So, moment to moment, we apply our finite capacity selectively to one or a few tasks. The more tasks we try to do simultaneously (multitasking) the fewer cognitive resources can be applied to each task, and performance suffers.

Most people cannot effectively multitask, even if they think they can. Only about 2.5% of people can genuinely multitask – perform two demanding cognitive tasks simultaneously without both suffering. For most people, multitasking comes at a price. We can divide our attention, but not without a decrease in performance. Many states now have laws reflecting this research – prohibiting talking on cell phones while driving.

What the famous gorilla video demonstrates is that attention itself is a task that suffers from from multitasking. We can focus all of our attention on one thing, or spread our attention out to monitor our environment, or do a little of both. You have a budget of attention, and you can spend it as you please at any moment, but you cannot increase your budget.

What the gorilla video research (and other research) also shows is that everyone does not have the same budget. Some people have more attention to spread around. Neuroscientists are not content simply documenting the finite attention and cognitive budgets of our brains – they also want to figure out what specific brain functions determine our attentional budget.

That is the focus of new research by psychologists Janelle Seegmiller, Jason Watson, and David Strayer. They reproduced the gorilla video experiment, but also tested the hypothesis that the ability to see the gorilla is linked to working memory capacity.

Working memory is the immediate information that you can hold and manipulate. When you do a math problem in your head, you are using working memory. It is distinguished from long term memory which can be stored for years to be retrieved, but cannot be manipulated – unless it is recalled into working memory.

The researchers identified students who had not seen the gorilla video. They then tested their working memory capacity with a standard test, which also involved distraction. They presented them with 75 math problems, each with a letter after the problem. They had to solve the problem and remember the letter sequences. To make sure they were doing the math problems, the researchers only counted those subjects who scored 80% or more on the math problems.

Then they made the students watch the gorilla video. Similar to prior research, 42% of the students did not notice the gorilla. Then they analyzed the data according to performance on the working memory task. They found that 67% of those who score highly in working memory noticed the gorilla, while only 36% of those with low working memory scores did.

The authors conclude from this that working memory capacity is tied to attention. This makes sense in that working memory can be a resource that contributes to the budget of attention. The more working memory capacity someone has, the more attention they have to spread around to various tasks. Or perhaps the better they are at switching their attention – working memory may contribute to attentional “flexibility.”

Of course, this is just one study and the results are primarily correlational, so we need to be cautious in applying the results. It is highly plausible that other aspects of cognitive capacity may have contributed to increased function in both memory and attention in these subjects. Perhaps those who were simply more awake and alert at the time of testing did better on both tasks.

This is a challenge faced by all neuroscientists, even to clinicians like myself. We often interrogate brain function by having subjects perform specific tasks. We can design those tasks to emphasize certain basic brain functions, and to isolate them as much as possible – but we can never perfectly isolate one specific function. This is because all tasks require multiple brain functions working together to produce a final result. That is how our brains are organized.

For example, in performing the memory task in this experiment subjects were also using their language function, and their visual ability, while they were filtering distractions, focusing their attention and using their working memory.

This means that researchers will have to examine this question from multiple angles. They will have to isolate the variables that are truly contributing to attentional flexibility. This study is a big clue, but is not the final answer.

Meanwhile, I find it interesting, whatever the underlying cause, that some people are significantly better at directing their attention than others. I wonder if this is an ability that is changing over time. Will poor multitasking ability be selected against because poor multi-taskers who try to talk on their phones while driving have a higher chance of being killed in a car accident?

I also wondered if the higher working memory and higher attentional flexibility in some subjects represents a pure neurological advantage – superior hardwiring, or does it reflect a zero-sum game, meaning that they have decreased capacity elsewhere? Are attentionally flexible people less able to think deeply without distraction? I can make either answer make sense, so I don’t think there is an obvious answer. And both answers may be correct – they are not mutually exclusive.

If we go back to the budget analogy and apply it to the entire brain – some people clearly have a larger budget of cognitive ability than others, but also there are different abilities on which their finite budget can be allocated. So you can increase one ability by increasing your brain’s overall budget, or by taking resources from other abilities.

And we have to add to this that cognitive abilities do not exist in isolation – so improving one ability may have cross-over benefits to other abilities.

In the end this new research is an interesting piece to a massively complex puzzle, but a picture is slowly emerging.

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