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.

35 responses so far

35 thoughts on “Attention and Memory”

  1. locutusbrg says:

    Interesting I had no idea that the true multi-taskers were such a minority.
    I think you know that risky behaviors, like driving while talking on a cell phone, is just a snapshot of risk taking behaviors that humans exhibit. There are few selective pressures that humans allow, given our societal forces. I am doubtful that this will ever have any measurable effect on multi-tasking ability. Multi-tasking may prove to be a advantage but humans often counter-intuitively negate evolutionary benefits. Negative traits are often reinforced by social structure. Examples such as Tay-sachs disease in select social/genealogical groups is an example of a lack of direct selective pressures on humans. In this case Air Bags. If it was just tongue in cheek statement forgive the above.

  2. mrwilson41 says:

    True multi-tasking is the ability to “perform two demanding cognitive tasks simultaneously without both suffering.” I wouldn’t call driving (sight) and talking on the cell phone (hearing) demanding. I would however call a task that uses your visual or hearing senses at the same time be demanding.

    Very interesting, Steve. It appears that some people have a bigger hard drives (long term memory), more RAM (short term memory), faster bus speed (how quickly to process the data), and/or multiple core CPU’s (multi-tasking).

  3. locutus – In recent years biologists have been moving toward the conclusion that humans are still evolving, despite the fact that we have a hugely outbred population and use technology to mitigate selective forces. Gene frequencies are still changing. For example, a couple that have been identified as linked to higher intelligence have been steadily increasing in the population.

    Tay-sachs and similar genetic diseases are not a good example. Even when they are selected against (they cause death before reproductive age) these diseases do not go away because there is a spontaneous mutation rate. Essentially they exist in equilibrium, with the spontaneous mutation rate replacing those selected against by manifesting the phenotype.

  4. daedalus2u says:

    This is very interesting and I have a good anecdote about multi-tasking. I used to be very good at multi-tasking. I remember listing to the radio while watching TV with the sound of both on at about the same level so I could switch back and forth, and then I would also be reading.

    I had a vivid experience after I raised my NO level with my bacteria. I was accustomed to listening to NPR while I was working on the computer, reading, writing, designing experiments, formulating hypotheses. After I raised my NO level I started to not be able to do that, that having NPR on was “too distracting”. This was surprising to me because I had been accustomed to working this way for many years. I had to turn NPR off, but then I was able to work at a higher level than I had been able to work at before and understand things that I had not understood before.

    My hypothesis of what is going on relates to functional connectivity as mediated by NO. One way that functional connectivity is measured is via fMRI, an MRI technique that looks at acute changes in blood flow (sub second) in the brain. It has found that there is very good correlation between this hemodynamic signal and neuronal activation (but the hemodynamic signal precedes the neuronal activation).

    My hypothesis is that with a slightly higher basal NO level, the neurogenic NO that causes the acute vasodilatation that causes the hemodynamic changes observed with fMRI has a longer range, a faster onset time and a longer duration. Larger volumes of brain get activated and so “larger” thoughts can be instantiated in those larger volumes. But there is only so much brain volume, so while it may be possible to hold larger thoughts, you can only have fewer of them. So I couldn’t do multi-tasking as well any more but I could think “bigger thoughts”. That is actually a good trade-off. Being able to do one important thing is more valuable than being able to do lots of unimportant things simultaneously.

    I think this is consistent with some of the effects of “stress” on cognition. Stress lowers NO levels. Cognitive activities that are complex and so take large brain volumes to accomplish are the first to go during stress, during dementia and during the cognitive decline that accompanies white matter hyperintensities or neuroinflammation.

    If the NO level falls low enough, I think that leads to the loss of the brain being “in sync”, and the ability to control and meta-program itself is lost. I think this is what happens in acute psychosis in NTs, and during a meltdown in ASDs.

    A brain control paradigm that facilitates multi-tasking during high stress could be advantageous during fight or flight where you might need to do multiple things, carry an infant, throw crap to distract a bear, while planning an escape route and calling for help.

    To answer your question, I think there is a trade-off, brain volume used for one thing can’t be used for something else. People with autism have been shown to have greater facility for some simple tasks, finding hidden figures for example. These simple sensory tasks require greater simple processing, which I think occurs locally and is facilitated in autism by the larger number of minicolums.

    Communication is much more difficult because it requires the emulation of another mind, and the tuning of communication to match what that other mind can understand. Savant abilities are actually pretty simple in comparison to communication. I see communication as the savant ability of NTs.

  5. Polymatheism says:

    Dr. Novella, this is truly fascinating. I’m wondering if you’ve considered doing any research as to how THC, the psychoactive cannabinoid compound, has an effect on the hippocampus, and what correlating effects can be traced from that?

    I’ve had some fascinating hypotheses about such a subject.

    Just wondering if you were aware of the journal of molecular pharmacology, and some of the research work being done in the field of Cannabinoid affinity and receptivity, as well and truly cataloging the several effects that cannabinoids and endocannabinoids seem to control.

    Just food for thought man, I love your show, and I love your blog. I personally have been promoting your podcast on my website, for my podcast. polymatheism.com

    Please check it out if you can, it’s very relevant, I talk about almost everything. a Polymatheist is someone who is an expert in nearly everything, a polymath, and an atheist/agnostic.

    Check my blog out at polymatheism.blogspot.com

    Frank Colletti

  6. ChrisH says:


    I wouldn’t call driving (sight) and talking on the cell phone (hearing) demanding. I would however call a task that uses your visual or hearing senses at the same time be demanding.

    Except you are not just looking and listening, you are also doing mental calculations as you drive. To change lanes you need to take in account the relative of both cars in front and behind the gap, or to turn into traffic you need to figure out if you have enough time from a dead stop to safely turn without getting hit by other cars, or did the yellow light change before or after you have time to stop at the intersection (dependent on whether the road is wet). I am sure only a true multi-tasker could parallel park and carry on a conversation (I’d like to figure out what the dimwit was doing when he/she parked behind my car less than an inch away from my back bumper!).

    I have actually had people swerve into me while talking on cell phones when they were walking!

    I have learned the limits of my attention when I try to do certain tasks while listening to podcasts. I found it works best for truly menial things like washing dishes, walking to the store, or gardening. Though sometimes while grocery shopping I miss what the podcast is saying while comparing prices and trying to remember if I’d forgotten something.

  7. HHC says:

    Invisible gorillas are easily understood, but what about real gorilla warfare, can military personnel pay attention to all the environmental changes in terrain as they focus on their assigned task? Does the ability to multi-task impact whether they safely return home or are heroes for the cause?

  8. kakaydin says:

    Is talking on a cell phone while driving cognitively different from talking to a passenger while driving? Is handling a cell phone while driving any different from handling a Big Mac?

    Perhaps the police should crack down on drive-thrus serving vehicles with more than one passenger.

  9. MaryP says:

    A very interesting study. For me it raised interesting questions as I saw the gorilla and last time I was tested I had a poor working memory. Maybe I am continuing to regain cognitive skills. But I also got distracted by the gorilla (and figuring out what it was) and lost track of the passes. So still not good at multitasking and showing a true lack of attention to the task.

  10. Chibi Janine says:

    I have just read the Invisible Gorilla book, I found it to be a really intriguing read. The section that interested me the most was the storing of memory and how our brains can create false memories of events.

  11. CivilUnrest says:

    I saw the gorilla, but that could be because of a gorilla-related-childhood-trauma I experienced that has made me hyper-aware of those nefarious jungle demons.

  12. ccbowers says:

    “Many states now have laws reflecting this research – prohibiting talking on cell phones while driving.”

    – Actually the laws have little to do with actual research… you are giving politicians too much credit here (and missing an opportunity to point out their error). The laws in the states that address this issue don’t ban cell phone use in general, but ban handheld cell phone use specifically, which has has nothing to do with attention. The laws do not reflect the distraction of cell phones do to inattention, but reflect the false notion that holding the phone is the major problem.

    “Most people cannot effectively multitask, even if they think they can.”

    – I think that it is important to emphasize how bad people are at assessing their inability to multitask. There are even data that suggest that people who describe themselves as good multitaskers are actually worse than average. (probably because they overestimate their performance they are less careful than those who are aware of problem of attempting to multitask)

    For most people in most situations, multitasking is a bit of a misnomer as it is really a matter of switching quickly between tasks.

  13. eiskrystal says:

    It could also be the amount of attention that you give each task. If you’re not that bothered about counting passes, you could then have enough timeslots left to see the gorrilla. What you would then have are people that can better adjust their processing usage to the task at hand.

    I’ve noticed that the more you do something, the more automatic it becomes, regardless of the difficulty. And therefore the less upfront processing it takes. If a lot of those that saw the gorrilla were math students then that could also skew the results… Though probably unlikely.

  14. D.P. says:

    Only about 2.5% of people can genuinely multitask – perform two demanding cognitive tasks simultaneously without both suffering.

    I don’t think it is correct to describe any fixed group of people as genuine multitaskers, because it largely depends on the tasks that they have to perform and how we measure it. If we measured those who can count correct and notice the gorilla, we would have much higher number (42 percent accordingly to one study), but clearly most of them would not pass the aforementioned driving and cell-phone talking test… Actually, the gorilla test is not about multitasking but inattentional blindness. If we were wanted to measure how good people at counting passes and noticing the gorilla, we would measure how accurate their results when they are completely focused on counting passes and compare to results when they do so after being told to watch out for something unusual.

    Finally, the fact that only 2.5% of people are capable of handling driving and talking on a cell phone without impairment does not mean that only 2.5% of people can drive safely when they are talk on the phone. There are those who stop speaking (or even listening to the phone) and completely focus on driving when situation requires that. So, they are safe drivers too, but they can not pass this multitasking test. (Though, AFAIK, most people unconsciously perceive human interaction as more important than watching the road.)

  15. SteveA says:

    Are there any excercises you can do to help improve your concentration, mental focus?

  16. ccbowers says:

    “There are those who stop speaking (or even listening to the phone) and completely focus on driving when situation requires that.”

    DP – How do you conclude that this is a safe behavior? The assumptions you incorrectly make here are: 1. that a person can recognize when his/her attention is needed on the road (which there will be a delay by definition due to switching of attention frome one task to the other, let alone the ability to recognize the driving situation) and 2. That driving does not require more attention (under real world conditions) than such a person can provide while on a phone

  17. ccbowers says:

    I do have a separate thought related to the video… no matter what video we show to demonstrate inattentional blindness, there will be confounding variables related to the experiences of the observers.

    For example, using the gorilla video to separate groups may just be selecting for basketball watchers, since people who often watch basketball may not need to pay as close attention to determine the number of passes (therefore more attention is available to see the gorilla). I’m not sure that selecting for basketball watchers isn’t happening more than selecting for those with increased working memory capacity, and this basketball watching group may carry other confounds with it.

  18. HHC says:

    Polymatheism, Latest research shows positive benefit for the bacopa plant with respect to the hippocampus. THC will not assist in counting costumed gorillas.

  19. ChrisH says:


    Invisible gorillas are easily understood, but what about real gorilla warfare, can military personnel pay attention to all the environmental changes in terrain as they focus on their assigned task?

    Do you mean military personnel attacking gorillas or guerilla warfare? 😉

    I recently read Sleights of Mind, which goes into much of the subject in this article. They actually visit a naval aviation school to learn about the training pilots use to find a pattern of attentional scanning, and get to fly in a simulation of a helicopter landing on an aircraft carrier.

  20. HHC says:

    The spelling of the latter word was meant. Just got done orbiting “Planet of the Apes.”

  21. ChrisH says:

    Oh. The reasoning was lost in the way it was typed. It is difficult to do irony and satire without voice inflection. But I did have a random vision of highly trained Marines going after gorillas and Jane Goodall.

    Still, the book on how magicians use our attentive deficits is a good read, and does have a couple of pages on the military.

  22. D.P. says:


    I did not make any of the assumptions that you wrote above.

    In particular, I was not speaking about being able to recognize something, but how people react to external signals competing for their conscious attention. Even without any phone, people often do _not_ devote all their conscious attention to driving — they may think about thousands things while driving a familiar route. Does it mean that all those drivers are dangerous? No, because their attentions (at least, vast majority of them) switches back to the road quickly. However, in case of talking on a cell-phone or with person sitting next to you, your attention may not go back to the road, because subconsciously you perceive human interaction as more important. So, it is not about being able to recognize something, but how you react to competing signals.

    For example, most people can drive and listen to a radio, and they still drive as safe as they would without listening to it. The reason why they drive safe is not that driving does not require more attention than a person can provide while listening to it, but because their conscious attention can switch quickly to the road if necessary. They may miss what was said at that moment on the radio as they are not so good at multitasking, but they still drive safe.

  23. Simmerja says:

    I’ve got a theory regarding the whole eating and/or talking while driving – it seems that maintaining high levels of attention and reaction ability while eating would be strongly selected for over a very long period of our evolutionary history, while verbal communication (especially that requiring a kind of abstract thought – say, talking on a cell phone to someone you can’t see) is a much more recent development. Might also answer why talking to someone in the car is not quite as distracting as talking on the phone…

    I’d love to get some simulator and fMRI time to test this, but it’s fun to wildly speculate in the interim!

  24. The research shows that talking on the phone is more distracting than talking to someone next to you in the car. There are several hypotheses (not mutually exclusive) to explain this:

    – It is not more distracting, but the other person present in the car provides an extra set of eyes and ears that compensates for the driver’s decrease in attention.

    – The physical presence of the other person provide some non-verbal cues that makes live conversation less attention demanding than phone conversation.

    – Audio quality over phones is not as good as live conversation (although getting better), so more attention is required to decipher the degraded speech over the phone.

  25. ccbowers says:


    I was going to write what Steven wrote above in response to your post. Cell phone talking appears to be more distracting than other distractions… you shift attention away from your radio quickly because you are not concerned with it in the same way… its not a 2 way interaction.

    My take is that phone conversations are more demanding of our attention for the reasons stated by Steve, but in addition phone conversations require more attention than a conversation with a person in the car because the driver is aware that the passenger see the situation on the road.

    The driver is therefore more comfortable with shifting his/her attention since the person can actually see what is going on. A person on the phone, on the other hand, may become annoyed at this shift in attention because they cannot “see” it in context… they may interpret it as the driver not valuing the content of the conversation.

  26. D.P. says:


    Cell phone talking appears to be more distracting than other distractions…

    Yes, on average, it is so. I have never said otherwise.

    But my point was not about what is more or less dangerous on average, but that the fact that there is some variety in how people react. For instance, the aforementioned article says that around 2.5% are capable of handling driving and talking on a cell phone without impairment. I only added that there is also some (probably also small) percent of people who are not capable multitasking but they can switch their attention easily as most people do when listen to the radio.

    phone conversations require more attention than a conversation with a person in the car because the driver is aware that the passenger see the situation on the road.

    That is only one of many possible hypotheses that Steven already mentioned above. And as he said, those hypotheses are not mutually exclusive. Moreover, I think it could be some additional possible reasons such as being conditioned to keep the conversation on the phone short, thus paying more attention to the phone.

  27. HHC says:

    ChrisH, Thanks for the book review, checked it out at the local library. Situational awareness is key to workload. CH-53 Super Stallions are impressive!

  28. ChrisH says:

    You’re welcome. Landing on a moving platform with anything is impressive!

  29. tmac57 says:

    I speculate from personal experience that ‘conversation ‘ in a car with passengers CAN be distracting but on a spectrum from benign to dangerous depending on the circumstances.A casual chat probably is less distracting than a heated argument,for example.A car full of noisy excited children in the backseat,coupled with a spouse trying to give you directions,is likely to much more disruptive to the driver’s concentration. The same may be true for listening to the radio.It might be more distracting listening to a talk radio political show that you disagree with,than soothing music.
    Like an airline crash,an auto accident may involve multiple factors:weather,traffic,other reckless drivers,road debris,and driver distraction.What might be a more or less ‘safe’ distraction,can become a key factor in whether or not an accident occurs when combined with other circumstances.

  30. sonic says:

    Perhaps it is the novelty of the phone conversation that is the problem.
    Will people get used to talking on the phone while driving?
    Personally I hope not- shut up and drive I say- but it does seem that people will get better at what they do often.
    tmac57 makes the good points on the other types of distractions– (sometimes it is my favorite songs that are most distracting to my driving…)
    Practicing focus is normal in sports today.
    A football quarterback must be able to focus down the field despite being rushed by large men.
    In golf one must keep one’s focus on the target despite it being out of visual range…
    This is something I do with people (help them maintain focus)- most improve with practice.

  31. ChrisH says:


    .A car full of noisy excited children in the backseat,coupled with a spouse trying to give you directions,is likely to much more disruptive to the driver’s concentration.

    Yes, I have pulled the car over and parked when bickering children became too distracting. The worst was when I had to park, open the windows, get out of the car and stood by it until they quieted down.

  32. rmc says:

    tmac57, the only time in my adult life that I’ve ever really yelled at my mother was in downtown New Haven, CT, because she would not stop reading out loud every. single. sign. along the roadway, as if it were some important marker of our journey or noteworthy change in traffic conditions. (“Pawn Shop! City Parking!”).

    Even my two year old (“Look! A truck! Look! A house! Look! A bird!”) is less distracting than an adult passenger shouting out meaningless landmarks.

  33. ChrisH says:

    Though nothing beats the distraction a college friend had: as she was driving to work a ferret popped up on to her leg. She almost drove off the road.

    Her husband had left a window open when he parked the car the night before, and someone slipped in a box with the ferret. They kept the ferret, and it lived with them when they went to graduate school in Iowa. Sadly, it turned out it had epilepsy, which is why they think it was abandoned.

  34. BillyJoe7 says:

    “A car full of noisy excited children in the backseat…is likely to much more disruptive to the driver’s concentration. ”

    The son of my old receptionist was killed as he was getting out of his car by a mother distracted by her children in the back seat.

  35. steve h says:

    Leaving aside internal distractions, external distractions are likely a significant contributor to car-pedestrian collisions. In particular, busy intersections with pedestrians on multiple corners combined with moving traffic can be too much for people to adequately handle. For instance, if you are trying to turn right on red, then you have to worry about traffic from two directions and pedestrians from four directions, since you may not be able to see what signals they are given.

    Thus, I don’t care about jaywalkers crossing midblock. I can see them, and I can pay closer attention to them. In the college town I’m in, many people like to complain either about the students crossing midblock, or people living in public housing doing so. But the collisions, at least that I know of, all happened to students crossing at the nearest crosswalk. That said, kids, please don’t toe the lines on the median lane. Toe other lines. Just not that one.

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