The Myth of Multitasking
Why your brain lacks the capital to pay attention to two things at once
Posted Jan 05, 2016
In 21st century schools and businesses we are taught to associate “multitasking” with efficiency, productivity, and competency. But what exactly does it mean to multitask?
How many different tasks can the brain focus on at the same time? Two? Three?
As it turns out, science has consistently shown that the human brain can only sustain attention on one item at a time (1). Our overestimation of our attentional capacity stems from a fundamental misunderstanding of the concept of multitasking and of the human attentional system as a whole.
The now felonious act of driving while talking on the cell phone will serve as a good example to examine the common misconceptions surrounding multitasking. The conscious experience of driving while talking on the phone is perceived as unified, fluid, and seamless, but this is a mental mirage. Rather than simultaneously attending to the conversation and the road, the brain is actually rapidly switching its attentional focus from the conversation to the road and back again (2).
Thus, we are indeed multitasking between the task of driving and talking on the phone, however, there is no temporal overlap. Given this fact, it is easy to understand why talking on the phone while driving is such a hazardous activity.
The brain’s attentional system functions like a searchlight in a pitch black night. Whatever external or internal item we wish to focus on is illuminated by our attentional searchlight. Importantly, our neurological searchlight has limited wattage so any focal point that falls outside the radius of its beam is cloaked in darkness. When we wish to attend to another item in our external or internal environment we swing the neurological searchlight to the new item, and by the definition of our finite attentional capacity, lose the original item to the inky darkness that envelops our beam.
Are there neurological correlates of the searchlight analogy?
We talked about the two major structures responsible for directing our attentional searchlight in a previous post: the anterior cingulate cortex and dorsolateral prefrontal cortex. The dorsolateral prefrontal cortex lies just under a point somewhere a little forward and above your temple. The anterior cingulate cortex can be found in approximately the same plane but lies in the middle of your brain.
The dorsolateral prefrontal cortex can be thought of as the director of the brain because it directs your attentional searchlight. When you choose to pay attention to the road while driving, it is the dorsolateral prefrontal cortex that generates that intentional focus. (3)
The anterior cingulate cortex provides the raw attentional capability, or wattage, of our metaphorical searchlight. Thus, the dorsolateral prefrontal cortex directs the beam of attention generated by the anterior cingulate cortex. (4)
How does this relate to mindfulness?
Most students of mindfulness will learn about mindful breathing in their first lessons. Mindful breathing simply entails paying special attention to the experience of breathing slow, deep breaths. The exercise often seems silly and largely pointless, but with our understanding of the attentional searchlight we can begin to appreciate the science behind the exercise.
When we first try the mindful breathing exercise our attentional searchlight swings wildly between the sensations associated with our breathing and the thought interlopers who incessantly rush through our consciousness. Our teacher will instruct us to not be discouraged by the distractions and to simply keep redirecting our attentional focus to the coolness at the tip of nose during inhalation, the rhythmic beat of our heart, or the rise and fall of our abdomen.
But why bother with this frustrating and difficult task of mastering our attentional searchlight?
The answer lies in the physiology of human attention. We can take advantage of our limited attentional capacity to vacation from the everyday labyrinth of thought. Each time we practice mindful breathing our dorsolateral prefrontal cortex grows stronger and becomes more capable of redirecting our attention towards a chosen focal point. “Growing stronger” is not a metaphor, the dorsolateral prefrontal cortex literally grows, increasing synaptic strength.
As it turns out, far from being a shortcoming of the human brain, our inability to focus on more than one item at a time provides an inroad to mindful practice.
Thus, by practicing mindfulness we build an off ramp for the superhighway of worry, self-blame, and obsession. We will inevitably have to return to the highway of thought before long, but it is surprising what a little break can provide.
- Kahneman, D. (1973). Attention and effort (p. 246). Englewood Cliffs, NJ: Prentice-Hall.
- Treisman, A. M., & Gelade, G. (1980). A feature-integration theory of attention. Cognitive psychology, 12(1), 97-136.
- Gelb, Douglas James. Introduction to Clinical Neurology. New York: Oxford UP, 2011. Print.
- Bush, G., Luu, P., & Posner, M. I. (2000). Cognitive and emotional influences in anterior cingulate cortex. Trends in cognitive sciences, 4(6), 215-222.