Stroop

About the Stroop exercise

Holding back an automatic response happens all day: reading the total on a bill instead of the bold number beside it, pressing the button for the floor you need rather than the familiar one, or answering the question that was actually asked. After a stroke or a brain injury, or with attention changes, the automatic response wins more often, and stopping it takes real effort.

Stroop is a free online version of the classic color and word interference task. A color word such as RED appears in mismatched ink, and the job is to tap the ink color, not the word. Every tap is timed, so a round ends with accuracy, speed, and the gap between matching and mismatched trials.

What Stroop practices

Response inhibition

Every mismatched ink trial asks the person to suppress the word already read and answer the color instead. The interference figure shows what that costs in milliseconds.

Processing speed

Patch trials remove reading entirely, so median reaction time on a patches round is a plain measure of how quickly a color is seen and matched to its button.

Selective attention

The word and the ink arrive together on every trial. Answering the ink means attending to one feature while letting the other pass.

How the tool works and what it records

Three stimulus types: patches, a solid color swatch with no reading; ink words, a color word in mismatched ink, the classic task; and counting, a row of repeated digits where the answer is how many, not what the digit says, the colorblind-safe option. Free presets: patches at 12 trials, classic ink or counting at 20, each with three colors. Pro unlocks the dials: 3 to 6 colors or options, 10 to 60 trials, and a matching-trials share of 0 to 50 percent. Large-print mode is free.

Trials appear one at a time with a 300 millisecond gap, each timed from stimulus to tap. Results report accuracy, median speed on correct trials, interference (mean mismatched time minus mean matching time) when a round has both, otherwise mean speed, and round time. A free account allows 5 rounds a day per tool; Pro removes the cap, exports two read-aloud sheets as a PDF, and saves each round to a session log.

Screen or paper?

The screen suits anyone who wants reaction times: it is the only way to see the interference cost, it scores instantly, and nothing needs printing. The counting variant exists only here. Paper suits the spoken version, where the person names colors aloud down a page while a partner times and counts errors, sessions with no wifi, and a file to keep.

The printable version is the Stroop worksheet set on rehabworksheets.com, and there is a free Stroop worksheet to try first, with no email required.

Using it well

• Start with patches. Run the 12 trial patches preset first. With no reading and no interference, its median speed is the baseline later rounds are compared with. Move to classic ink once accuracy on patches is steady.
• Read the interference figure, not just accuracy. Accuracy can be perfect while mismatched trials run far slower. The note under the tiles gives both averages, and the gap between them is the number to watch from one session to the next.
• Change one dial at a time. With Pro, moving from three colors to four adds green and a fourth button, which changes the task more than extra trials do. Adjust one setting per session so a slower round has one explanation.
• Adapt for hand or speech difficulty. Answers are large buttons, so no speech is needed, and large-print mode enlarges the stimulus and the buttons. Trials follow each other automatically, so pick a shorter trial count and abandon the round when a break is needed.

Common questions