Hack55.Confuse Color Identification with Mixed Signals | Mind Hacks. Tips and Tools for Using Your Brain

Hack 55. Confuse Color Identification with Mixed Signals

When you're speaking, written words can distract you. If you're thinking nonlinguistically, they can't.

The Stroop Effect is a classic of experimental psychology. In fact, it's more than a classic, it's an industry. J. Ridley Stroop first did his famous experiment in 1935, and it's been replicated thousands of times since then. The task is this: you are shown some words and asked to name the ink color the words appear in. Unfortunately, the words themselves can be the names of colors. You are slower, and make more errors, when trying to name the ink color of a word that spells the name of a different color. This, in a nutshell, is the Stroop Effect. You can read the original paper online at http://psychclassics.yorku.ca/Stroop.

5.4.1. In Action

To try out the Stroop Effect yourself, use the interactive experiment available at http://faculty.washington.edu/chudler/java/ready.html¹ (you don't need Java in your web browser to give this a go).

Start the experiment by clicking the "Go to the first test" link; the first page will look like Figure 5-1, only (obviously) in color.

Figure 5-1. In the Stroop experiment, the color of the ink isn't necessarily the same as the color the word declares

As fast as you're able, read out loud the color of each wordnot what it spells, but the actual color in which it appears. Then click the Finish button and note the time it tells you. Continue the experiment and do the same on the next screen. Compare the times.

The difference between the two tests is that whereas the ink colors and the words correspond on the first screen, on the second they conflict for each word. It takes you longer to name the colors on the second screen.

5.4.2. How It Works

Although you attempt to ignore the word itself, you are unable to do so and it still breaks through, affecting your performance. It slows your response to the actual ink color and can even make you give an incorrect answer. You can get this effect with most people nearly all of the time, which is one reason why psychologists love it.

The other reason it's a psychologist's favorite is that, although the task is simple, it involves many aspects of how we think, and the experiment has variations to explore these. At first glance, the explanation of the task seems simplewe process words automatically, and this process overrides the processing of color information. But this isn't entirely true, although that's the reason still taught in many classes.

Reading the word interferes only if two conditions are fulfilled. First, the level and focus of your attention has to be broad enough that the word can be unintentionally read. Second, the response you are trying to give must be a linguistic one. In this case, the required response is spoken, so it is indeed linguistic.

Avoiding reading is easier when the color to report is disentangled from the word. If you have to respond to only the color of the first letter of each word and the rest are black, the confusion is reduced. Ditto if the word and block of color are printed separately. In these cases, we're able to configure ourselves to respond to certain stimuli (the color of the ink) and ignore certain others (the word). It's only when we're not able to divide the two types of information that the Stroop Effect emerges.

It's probably this kind of selective concentration that renders otherwise bizarre events invisible, as with inattention blindness [Hack #41] when attention on a basketball game results in a gorilla walking unseen across the court.

The second condition, that the response is linguistic, is really a statement about the compatibility between the stimulus and response required to it. Converting a written word into its spoken form is easier than converting a visual color into its spoken form. Because of immense practice, word shapes are already linguistic items, whereas color has to be translated from the purely visual into a linguistic symbol (the sensation of red on the eye, to the word "red").

So the kind of response normally required in the Stroop Effect uses the same codelanguageas the word part of the stimulus, not the color part. When we're asked to give a linguistic label to the color information, it's not too surprising that the response-compatible information from the word part of the stimulus distracts us.

But by changing the kind of response required, you can remove the distracting effect. You can demonstrate this by doing the Stroop Effect task from earlier, but instead of saying the color out loud, respond by pointing to a square of matching color on a printout. The interference effect disappearsyou've stopped using a linguistic response code, and reading the words no longer acts as a disruption.

Taking this one step further, you can reintroduce the effect by changing the task to its oppositetry responding to what the written word says and attempting to ignore the ink color (still pointing to colors on the chart rather than reading out loud). Suddenly pointing is hard again when the written word and ink color don't match.²

You're now getting the reverse effect because your response is in a code that is different from the stimulus information you're trying to use (the word) and the same as the stimulus information you're trying to ignore (the color).

Take-home message: more or less mental effort can be required to respond to the same information, depending on how compatible the response is with the stimulus. If you don't want people to be distracted, don't make them translate from visual and spatial information into auditory and verbal information (or vice versa).

5.4.3. End Notes

This experiment is part of the much larger Neuroscience for Kids web site: http://faculty.washington.edu/chudler/neurok.html.
Durgin, F. H. (2002). The reverse Stroop Effect. Psychonomic Bulletin & Review, 7(1), 121-125.

5.4.4. See Also

Two further papers may be of interest if you'd like to explore the Stroop Effect and the underlying brain regions responsible: Besner, D. (2001). The myth of ballistic processing: Evidence from Stroop's paradigm. Psychonomic Bulletin & Review, 8(2), 324-330. And: MacLeod, C. M., & MacDonald, P. A. (2000). Interdimensional interference in the Stroop Effect: Uncovering the cognitive and neural anatomy of attention. Trends in Cognitive Sciences, 4(10), 383-391.