Why Does Reading Words About Old Age Make You Walk Slower?

Daniel Kahneman, psychologist and Nobel laureate in Economics, devotes part of his book Thinking, Fast and Slow (2011) to describing one of the most cited experiments on how an idea can influence an action without the person noticing at all. The experiment, the work of psychologist John Bargh and his team, later became known as the “Florida effect,” and today ranks among the classic examples of what psychology calls priming: the phenomenon by which exposure to an idea predisposes you, without realizing it, to think or act in a way consistent with it.

The experiment: forming sentences from loose words

Bargh asked students at New York University, mostly between eighteen and twenty years old, to form four-word sentences from a set of five terms handed to them (for example: “yellow, finds, he, it, instantly”). The exercise looked like a simple language test. What the students didn’t know is that, for half of them, many of those word sets included terms culturally associated with old age: Florida, forgetful, bald, gray, wrinkle. None of those words meant “old” explicitly; it was enough that they evoked the idea indirectly.

After finishing the task, each student was sent to another office located a bit further away, down a hallway. That brief walk was, in fact, the real point of the experiment: the researchers timed, without the participants knowing, how long each one took to walk it.

The finding: walking slower without knowing why

The students who had formed sentences with words related to old age walked more slowly to the second office than the others. The difference wasn’t dramatic, but it was systematic and measurable. Bargh had predicted it in advance, precisely because old age is culturally associated with physical slowness, and his hypothesis was that simply activating the idea of “old age” would be enough to indirectly activate the behavior of “walking slowly,” without ever passing through a conscious thought like “now I should walk more slowly.”

When participants were later asked if they’d noticed anything in the sentence exercise, none identified the shared theme of the words, and all insisted that nothing that happened afterward could have been influenced by that first task. The idea of old age never reached their conscious mind, and yet it shaped their physical behavior a few minutes later.

Two linked stages

Kahneman describes this mechanism as a two-step sequence:

• First stage: the set of words activates, in associative memory, the general idea of old age, without the word “old” ever needing to appear.
• Second stage: that activated idea, in turn, predisposes a culturally associated behavior (walking slowly), again without conscious involvement.

This kind of influence of an idea on a physical action is called the ideomotor effect. Kahneman notes, with a hint of humor, that the reader of his book may have felt slightly predisposed after reading the paragraph about the experiment: if at that moment they felt the urge to get up for a glass of water, they probably did it a little more slowly than usual.

The link also works in reverse

A study conducted at a German university replicated the idea, but reversing the order of cause and effect. Instead of activating an idea first to observe a behavior afterward, a group of students was asked directly to walk around a room for five minutes at a deliberately slow pace, a third of normal speed. After that brief physical exercise, those same students recognized words related to old age, like “forgetful,” “old,” or “lonely,” faster than a control group.

This confirms that the link between idea and behavior isn’t one-directional: thinking about something can predispose you to act consistently with it, and acting a certain way can, in turn, reinforce the ideas culturally associated with that way of acting. Kahneman calls this kind of reciprocal connection part of the associative network, the same network that lets having fun tend to make us smile, and smiling, even without a real reason to, tend to make us feel in a better mood.

The pencil-between-the-teeth experiment

The book includes another experiment that illustrates the same principle even more strikingly. A group of students was asked to hold a pencil in their mouth in two different ways: with the eraser pointing right (which forces the facial muscles into a position similar to a smile) or with the tip pointing forward (which instead forces an expression closer to a frown). Without anyone saying anything about facial expressions, they were asked to rate how funny some Gary Larson cartoons were.

Those holding the pencil in the way that forced an involuntary “smile” rated the cartoons as funnier than those holding it the other way. In a related experiment, people made to adopt an angry expression (furrowing their brow) showed a more intense emotional reaction to harsh images, like scenes of malnourished children or accidents.

Findings like these, though they may seem anecdotal, illustrate something that runs through much of Kahneman’s book: much of what we consider our “own” decisions and judgments is shaped by automatic associations we’re not aware of at all, a theme that connects directly to how many of the quick intuitions the analytical profile describes form, versus the more deliberate judgments of a more intuitive style.