How to Think Faster: Reaction Speed vs Thinking Speed

In 1996, the American psychologist Timothy Salthouse published “The processing-speed theory of adult age differences in cognition” in Psychological Review. The idea is that as adults age, the speed at which many mental operations can be carried out goes down, and that this slowing leads to declines in a wide range of cognitive functions, such as memory and reasoning.

Many people feel that they are not as quick as they used to be. This post breaks that feeling down into reaction speed, processing speed and thinking speed, covers what research has found, and suggests some things to try in conversation and at work.

“Quick-witted” is not one ability

The phrase “thinking fast” lumps together several different things.

• Reaction speed. How quickly you press a button after a signal.
• Processing speed. How quickly and accurately you can do a simple task. A common test has you copy symbols while looking at a key that pairs digits with symbols.
• Thinking speed. How quickly you give a sensible answer when asked a question in a meeting. This also involves recalling what you know and putting an answer together.

These three change differently with age. A 2015 study by Hartshorne and Germine used standard intelligence test data and a large amount of data collected online to look at the age at which various cognitive abilities peak. A digit-symbol test of processing speed peaked in the late teens, while vocabulary peaked much later in life. The authors write that there is probably no single age at which people are at their best on most abilities.

What happens when processing slows

Salthouse’s paper gives two ways that slower processing affects other functions.

One is running out of time. If early steps take longer, less time is left for later steps, and they may not finish. The other is that the results of earlier steps may be lost by the time later steps are done. In conversation, this is close to the feeling of missing the second half of what someone said while still working out the first half, or forgetting your first point while building your answer.

That said, the paper is a theory to explain age differences. It is not a way to diagnose any one person’s thinking speed.

Speed and accuracy trade off

When you try to answer faster, you make more mistakes. This is called the speed-accuracy tradeoff, and according to a 2014 review by Heitz, it is seen across species, from insects to rodents to primates.

There is an important point here. When we want to think faster, what we really want is to be faster at the same level of accuracy. Rushing, in most cases, just buys speed by giving up accuracy. If you answer quickly in a meeting and then have to correct yourself later, it is hard to call that faster.

More choices, slower responses

The link between the number of choices and the speed of a response has also been studied for a long time. Hick’s law, known from work such as Hick’s 1952 paper, describes how the time it takes to choose grows as the number of options grows.

In daily life, this means that laying out every option on the spot and choosing among them will always be slow.

Knowing more lets you think faster

Knowledge plays a big part in thinking speed. In a 1973 study by Chase and Simon, chess players of different strengths were shown positions from real games for about five seconds and asked to rebuild them on a board. Stronger players rebuilt them better, but on boards where the pieces were placed at random, the difference became small. Stronger players are thought to see familiar arrangements as chunks at a glance, rather than remembering pieces one by one.

The same can be said of conversation at work. Many people who seem quick-witted are not thinking from scratch on the spot. They are fitting the question to patterns they already know.

Things to try in conversation and at work

What follows is one example based on the research above. It is not a method that research has tested.

Decide in advance. Prepare answers to the questions you are often asked. As Hick’s law suggests, the fewer options you choose from on the spot, the faster you can answer. One way is to write down three things you are likely to be asked before a meeting.

Practise recalling. Knowledge you use often sticks better when you practise recalling it without looking than when you reread it. I wrote about this in How to Improve Your Memory as an Adult. The more knowledge you can recall easily, the better the base for thinking quickly.

Start with the conclusion. If you lose your point while building an answer, saying the conclusion in one line first and then adding reasons makes it less likely you will forget it halfway.

Do not rush. If speed and accuracy trade off, then saying “let me think for a moment” can be seen as choosing accuracy rather than being slow.

Sleep well. Sleep loss lowers attention, as the research in Can’t Stay Focused? shows. On a day when you feel slow, last night’s sleep is worth checking first.

About processing speed training

There are also ways to train processing speed itself. In the American ACTIVE study of older adults, people who received speed training got faster on the trained tasks, and the effect lasted a long time. On the other hand, as I wrote in Does Brain Training Work?, there is no clear evidence that gains on practised tasks spread to other settings such as work or conversation.

So if you do a speed task every day, you should get faster at that task, but that does not mean you will answer faster in meetings. Tasks like these can serve as a gauge of how you are doing that day. If slow thinking is causing serious problems at work or in daily life, please talk to a doctor.

About BrainDojo

BrainDojo is an iPhone and iPad app for keeping up daily brain training with short mini-games.

The daily Brain Dojo Check is a short test with one task from each of three areas, Processing Speed, Inhibitory Control and Working Memory, and it gives your result as a radar chart and a rank. The tasks are simplified app versions of cognitive tasks used in research, and the result is not a medical diagnosis. Your score should go up as you keep doing it, but most of that likely comes from getting used to the tasks. It can serve as a gauge of how you are doing day to day.

The training is grouped into lanes such as Calculation Boost, Memory Boost, Attention Boost and Handwriting Training. You answer by handwriting with your finger, speaking, or tapping. Every training except the newest ones is free to play, and so are Today’s Training, the Brain Dojo Check once a day, and a calendar where you stamp the days you trained. The free version shows ads. BrainDojo Plus removes them and opens the new trainings anytime. When a new training appears in Today’s Training, you can play it free that day.

Getting Started with BrainDojo walks through the first session, and BrainDojo Free vs Plus compares the two plans.