Fun with Stroop

April 30, 2008

The Stroop Effect is often used to demonstrate the nature of automatic processing versus conscious visual control. It also illustrates our ability to quickly recognize word shapes based on familiarity, even more quickly than color.

This effect was first described by J. Ridley Stroop in 1935, and was demonstrated by giving participants lists of words printed in various colors of ink. The participants were instructed to name the color of the ink for each word as quickly as they could.

Control condition
In Stroop’s original study, the control condition consisted of neutral, non-color related words (for example, the word “dog” appeared in green ink and “chair” in blue ink).

Compatible condition
Next, the compatible condition consisted of a list of colors – the words red, green, blue, etc. – printed in their corresponding ink colors (“red” was printed in red ink, “blue” in blue ink, and so on).

Incompatible condition
The final list consisted of the names of colors written in different colored ink (for example, the word “red” appeared in green ink).

Stroop found that people could name the color of the ink faster in the compatible condition (“red” in red ink) than the control condition (“dog” in green ink). However in the incompatible condition, people took longer to name the color of the ink (“red” in green ink) than in the control condition (dog” in green ink). One explanation is that naming the color of the ink is an unfamiliar task to most people and requires conscious effort, while reading is so well practiced that it becomes automatic. So, in the third condition people experience interference – as they try to name the color of the ink, they have already read the word (for example, “red”) and need to consciously adjust their answer.

Try Stroop’s experiment for yourself and see if it takes longer to complete list number 3. Remember, for each group you’re trying to say the color of the words.


Context and expectations

March 30, 2008

Context and Expectation

A classic example of the importance of context in pattern recognition. Although the central character is the same when viewed inline either vertically or horizontally, its meaning differs depending on contextual cues from its surroundings.

The Road to Clarity

October 24, 2007

typeface legibility

As young readers we learn to make sense of words by memorizing shapes and vocalizing each individual letter in order, one at a time, until the entire word is formed. As we learn, we become able to recognize entire words at a glance, based on familiarity and context, without the need to work out individual character shapes.

Clearview, the typeface slated to replace Highway Gothic as the standard font for US road signage, takes advantage a driver’s perceptual ability to recognize word shapes, thereby allowing them to read quickly at high speeds and at greater distances than is possible with today’s signs.

Here’s a great NY Times Magazine article (registration required) about the design and testing of Clearview. Additional info and a commercial version of the font is available for purchase at