I picked up a bad habit during lockdown: binge Netflix at double speed, while scrolling through the Twitter cesspool on my phone. I think I feel mentally stimulated, and trick myself into believing that I’m learning more in less time.
Yeah, no. A new study, published in Nature, took a deep dive into media multitasking and found that it correlates with “tip of the tongue” syndrome. Those times when you know you remember something, but you can’t bring it to mind to tell others about it and you get frustrated? It gets worse when you’re simultaneously staring at two screens. The end result is that you’re less able to retrieve a memory—a word, a name, an answer to a quiz—or in more colloquial terms, you forget, at least in that moment.
I’m fine with not recalling angry tweets, but the implications are far wider. For kids currently relying on virtual schooling, for example, it’s easy to get distracted if they have to juggle multiple screens or multiple windows—one for a video lecture, the other a chat for Q & As. For a contestant in Jeopardy!, stumbling at recall could mean a failed grasp at game show hall-of-fame. For an interviewee, a sudden lapse in memory may kill chances at a dream job.
“As we navigate our lives, we have these periods in which we’re frustrated because we’re not able to bring knowledge to mind, expressing what we know,” said study author Dr. Anthony Wagner at Stanford University. “Fortunately, science now has tools that allow us to explain why an individual, from moment to moment, might fail to remember something stored in their memory.”
The key, surprisingly, seems to be what happens in the brain and under the hood of consciousness—long before you’re aware that you’ve remembered a memory, or that it’s slipped your mind.
Attention Is King
Remembering something specific is a complicated problem for the brain. First, you have to encode the memory into your biological neural networks; then it has to stick around, a process aptly called “consolidation.”
The third part is where the study was focused: you need to be able to retrieve that stored memory at the right time, the right place and—most likely—in order to help you in a certain scenario.
Too complicated? An example: you finally caught up with an old friend you haven’t seen in years. They bring up that party you both went to and, with their eyes, ask you to respond. Your brain not only needs to have the memory stored, but you also need to be able to fish it out in a “goal-directed” way so that you can answer the question.
Scientists have long known several factors that make recall difficult. The memory could fade. An external trigger or cue might not be available. But one critical component, at the heart of recall, is “preparatory attention.” In essence, it’s the brain’s ability to shift its processing muscle towards relevant goals—“I need to answer that question!”—but before you’re even asked the question. “Such preparatory attention goes to the very heart of the brain’s capacity to predict, and to organize its data gathering and processing accordingly,” said Dr. Charles Shroeder at Columbia University, who wrote about how this mysterious power works in the brain.
While it sounds abstract, preparatory attention can actually be captured in brain waves using electroencephalogram (EEG). EEG places electrodes on the scalp, and measures fluctuations in the brain’s electrical activity across large areas. Previous work suggest that our brains spontaneously fluctuate in their level of preparatory attention.
The new study asks: are those unfortunate drops in attention why we sometimes can’t remember?
New Rules, New Tools
To get to the bottom of it, the team recruited 80 young adult participants aged between 18 and 26 and hooked them up to EEG. Specifically, the team hunted down a type of brain wave called the “posterior alpha power,” measured at the back of the skull.
“Increases in alpha power…have been related to attention lapses, distractibility, and so forth,” explained study author Dr. Keven Madore at Stanford.
As another measure, the team also examined the diameter of the participants’ pupils as they performed a goal-directed memory task. Because the control of pupil size is related to brain areas involved in attention, scientists know that constrictions in pupil diameter, particularly before switching tasks, is related to drifting attention—for example, slower reaction times and mind wandering. Finally, the participants also filled out a questionnaire about their self-perceived level of engagement during the study.
It wasn’t an easy task. The volunteers stared at a computer screen showing nearly 170 objects—a hat, pan, bracelet, or insect, for example—and were asked to rate a subset on whether they were “pleasant or unpleasant,” or whether the image looked “large or small.” The crux of the study came 10 minutes later, when they were challenged with a recall task. Each person looked at over 250 objects, some old, some new. They were then asked whether they remembered the object and whether it was more pleasant or bigger than before, and had to respond as quickly as possible.
Crucially, there was a slight lag between the cue and when they had to log their response, the team said. This made it possible to examine brain waves that correlate with attention at the moment just before they successfully retrieved—or forgot—the memory.
Using both EEG and pupil diameter to measure attention, the team found that people with lower sustained attention ability performed worse on the memory tasks. Critically, they were able to correlate failures in attention in the sliver of time right before recall with memory performance.
“While it’s logical that attention is important for learning and for remembering, an important point here is that the things that happen even before you begin remembering are going to affect whether or not you can actually reactivate a memory that is relevant to your current goal,” explained Wagner.
While many have studied attention and memory before, the study stands out in its use of multiple tools to measure attention. Moving from cold sterile labs to the outside world, the team then asked whether media multitasking disrupts memory recall—and whether attention lapses are to blame.
Using a battery of questionnaires, the participants self-reported on how often they multitask on multiple screens and were given a score—higher represents heavier multitasking. The team then examined how these multitasking scores related to their posterior alpha waves and pupil diameters measured during the lab memory task.
You guessed it: those who engaged in heavier media multitasking also had the brain wave and pupil profile of lapsed attention. More frequent or disruptive lapses of attention “is one plausible explanation for why heavier media multitasking is correlated with poorer memory,” the team said.
Madore stresses that this observation is only correlational at this point, in that we can’t definitively say that staring at multiple screens causes bad memory recall. However, with a new toolkit in hand for studying attention, it’s now possible to dig into how exactly the link works. Future studies, for example, can track people for long periods of time to see whether differences in media multitasking leads to differences in attention—or vice versa.
The team also suggests that we might be able to “hack memory” by using targeted attention-training exercises. For example, wearable eye sensors could detect lapses in attention in real time by measuring the pupil diameter, and alert the wearer to refocus.
Looking further ahead, the same multi-pronged toolset used in the study could provide unprecedented glimpses into memory: why our recall sometimes fails, why some of us access our memory database better than others, and what happens in memory disorders such as Alzheimer’s.