Fragmented attention

You are halfway through a difficult paragraph when your phone vibrates. The message takes perhaps fifteen seconds to read and another twenty to answer, so less than a minute later you put the phone down and return to exactly the same sentence. Nothing important seems to have happened, yet you read the sentence again, then the one before it, because somewhere during those thirty-five seconds you lost more than time: you lost your place inside the thought. This is the hidden cost we reached at the end of the previous chapter. An interruption occupies whatever time you give to it, but some activities also require a period of reconstruction after you return. The clock can measure how long you were looking at the phone, while failing to measure how long it takes to become fully engaged with what you were doing before.

Researchers have studied different parts of this problem under terms such as task switching, interruptions, media multitasking, attention control, and resumption after interruption. These areas are related but not identical, and their findings should not be compressed into the popular claim that every glance at a phone destroys twenty minutes of concentration. What the research does give us is a more interesting framework for understanding why moving attention between tasks can create costs that are easy to miss.

Start with a simple distinction. Doing two things at the same time is not always difficult, because many combinations require different levels and kinds of attention. You can walk while talking, listen to music while washing dishes, or drink coffee while reading because at least one part of the combination can often proceed with relatively little conscious control. The situation changes when two activities compete for the same cognitive resources.

Try reading a complicated argument while composing a meaningful message, or solving an unfamiliar mathematical problem while following a conversation about something important. At some point, what feels like simultaneous activity usually becomes movement between activities, because both tasks demand more deliberate processing than can comfortably occur at once. This is why the word multitasking can be misleading. A computer can perform forms of parallel processing, but human attention does not simply create two equally complete streams of conscious thought whenever we ask it to. In many everyday situations, what we call multitasking involves rapid switching: task A, then task B, then back to A, perhaps so quickly that the movement feels simultaneous.

Each switch can require the mind to update what matters. The goal of the email is different from the goal of the spreadsheet, the rules of a conversation are different from the rules of a programming problem, and the information you need to keep available changes with the task. Moving between them therefore involves more than moving your eyes from one screen to another; it can require changing the mental configuration used to decide what deserves attention and what should happen next.

This passage is from Scroll on Purpose. Read the introduction and first chapter, browse the guides, or see buying options.