Taking the Stroop Test

I took the Stroop test as part of my ASD evaluation and I’ve seen it recently on a list of online autism evaluation tests. While not strictly an autism test, it is often part of the test battery that is given at neuropsychological evaluations for autism.

The format of the Stroop test that I took during my evaluation was:

  • verbally reading a list of color words (blue, red, green) printed in black ink
  • verbally stating the color of a series of Xs printed in blue, red or green ink
  • verbally reading a list of color words that were printed in colored ink (i.e. RED printed in blue ink or RED printed in red ink)

The Stroop test is a test of executive function. Our brain’s natural tendency is to read words that we’re presented with; noticing the color of the ink the word is printed in is a secondary priority. The Stroop test asks us to inhibit our first instinct (reading the word) in favor of stating the color of the ink. Doing so draws heavily upon the executive functions of inhibition and attention.

Because autistic people typically have impaired executive function, we often score below average on the Stroop test. The time taken to complete the test is also seen as a measure of cognitive processing speed, another area where autistic individuals will typically have a below average result.

There are quite a few other conditions that also cause cognitive “interference” on this test, resulting in below average scores, including ADHD, dementia, brain damage, depression, schizophrenia and addiction. While the results of the Stroop test can give you some insight into your executive function abilities, it’s not strictly related to being or not being autistic.

Taking the Test

You can take a mini version of the Stroop test here.  The test site is ugly and has lots of ads that you’ll have to ignore. Read the instructions in the center of the page and click the green button when you’re ready to begin. The test has 20 items and will take a couple of minutes to complete. You’ll receive your scores on the final screen of the test.

Scoring the Test

The reason I called this a mini version of the Stroop test is because it has only 20 trials. The version of the test I took at my evaluation had 300 trials across the 3 different types of tasks, with each set of 100 having a 45-second time limit.

The online version presents 15 incongruent (ink color and word do not match) and 5 congruent (ink color and word match) trials. It then gives you a score showing your congruent and incongruent results, with number correct and the average processing time for each. Generally, most people respond more quickly the congruent pairs than the incongruent pairs.

Here are my scores for the online version:

  • Congruent: 5 Correct, avg response time: 11.78 seconds
  • Incongruent: 15 Correct, avg response time: 10.20 seconds

(Admittedly I have an advantage because I was familiar with the test format and I think my scores reflect that.)

And here are my scores for the paper version (raw score, followed by percentile – in both cases higher is better):

  • Word (color words/black ink): 82, 12th percentile
  • Color (Xs/3 ink colors): 91, 27th percentile
  • Color-Word (color words/3 ink colors): 110, 75th percentile
  • Interference (calculated from other scores): 121, 92nd percentile

If you look at both sets of scores, you’ll see that I’m better at the incongruent tasks. I got higher scores on the Color-Word and Interference scores for the paper test and had a faster average response time for the incongruent pairs on the online test.

When I saw my scores from the paper test, I was shocked by how poorly I did on the first two tasks, which felt effortless when I was taking them. I have no explanation for the disparity in my performance, except that maybe when a task is more difficult, I pay closer attention and therefore do well on it. I had a similar outcome on another “easy version-hard version” test during my evaluation which supports this supposition but there may be another explanation that has gotten by me.

The Bottom Line

How useful is the online Stroop test? I think it’s more valuable as a curiosity satisfier than an actual measure of cognitive processing. First, it doesn’t have the “priming” tasks of reading the words in black ink and naming the colors of the Xs, which create performance patterns in the brain, supposedly making the color-word task more difficult.

Second, there is no overall time limit so the test taker doesn’t feel pressured to rush through as many items as possible to complete the test in the allotted time. The response time score compensates for this a bit, but there’s no mention at the beginning of the test that one is being timed.

Finally, the number of items is too few to cause the cognitive fatigue that makes the paper test challenging.

31 thoughts on “Taking the Stroop Test”

  1. Ugh, I missed one on the incongruent ones and didn’t even realize it:

    5 15.242 seconds
    14 22.07 seconds

    I took longer because I kept reading the direction sentence above the colored word every time, even though I was pretty sure it wasn’t going to change. But it was there, so I read it.

    This is similar to one of the games they have on that Luminosity site, so I was also familiar with the concept, but I wasn’t terribly fast with it on that site either. 😛

  2. I just tried the online one, and I’d like to cast some doubt on what it’s doing, namely that it just told me the fastest of my average times was 15 seconds. I’m about 95% confident the 20 question test did not take me 5 minutes (15s x 20 is 60s x 5); my estimate would be under a minute.

    It showed me taking 20% longer on the congruent tests, but I don’t know how much I should believe it because of my first observation there. My son has been diagnosed with ASD (specifically Asperger’s). I haven’t, and I guess I wouldn’t be under the strict “is it impairing your life” definition, but I strongly suspect if there was a “how your brain works” definition I’d be on the spectrum too.

  3. I had originally thought the estimated time was the total time it took for each type of question (because 37s would have been about right for my first try), but I’ve done it twice more and the first time my total time was 42s, but it had my ‘averages’ as 34s and 28s (total 62s). And then the second time, I took 35s and it had my ‘averages’ as 12s and 10s… so yeah, I have no idea. There doesn’t seem to be any definition or detail on how the calculate the time score.

    1. … also, the first ‘test’ where you just read the colour of the word then time yourself … this does not take into account whether you read the words correctly or not. One could simply read word colour or colour of word quite fast . . . it seems to prove absolutely nothing. If you haltingly read them with the mission in mind that obviously takes a few more seconds. BUT this is as far as I got, bc the seconds selections and submit buttons would not respond (I assume bc of the phone)
      I assumed I would be excellent at this as my career is painting, but it was a rather ‘halting-pausing’ endeavor for even me … and I only saw the first two word sets … lol

      This is kinda similar to little jokes that people tell …
      ‘George Washington’s white horse fell into a black-mud hole.
      What colour was George Washingtons horse?’
      As a child, you were apt to say ‘Black!’
      which is, for the horse, momentarily correct, but technically, the horse is indeed white regardless.

      There are several of these kinds of little mental pause jokes – sometimes, I am amazed at how instantly some people answer them – I think,
      ‘They must have just heard it elsewhere!’
      I would also enjoy the brief ‘pause’ as the person considers the two simple facts about the horse.
      I wish I could think of the other similar ones …

  4. That was a lot harder than I thought it would be. I tripped and stumbled all over it, and one time I clicked on a color that corresponded neither to the word or color! Ugh…

    Congruent: 5, 11.318s avg
    Ingcongruent: 13, 10.153s avg

  5. I found it took me longer to find the correct button and move the cursor over it (using the touchpad on my laptop) — 4-5 seconds — than to decide what the correct answer was (less than a second). I got them all correct, and there was no significant difference between the times for congruent and incongruent. Pretty much inconclusive, I think.

  6. I ran it twice this afternoon and got all correct, faster for incongruent than congruent.

    I think having them match makes me think I’ve got it wrong maybe? Because I’m concentrating so hard on ignoring the words?

  7. . . . here’s an interesting & humorous thought … are there any sites for Neurotypical thinkers?
    . . . no . . . they are (allegedley) the vast majority of humans, they don’t think about how they think . . .
    They have always thought everyone thinks exactly like them. They are very incredulous towards us when we do not ‘fit’ properly in the world with our communicarion, mannerisms, ideas… seems hard for them to accept.
    They don’t wonder if they need to take tests for how THEY think.
    … all of their answers would be incomplete, vague, & ambiguous anyway . . . actually, if there were such a site, every subject would just trail-off into ambiguity and factlessness …
    The only reason we (ok, ‘Aspies’) enjoy these sorts if tests is because we have always been told by the vast majority of humans that we think/act/are different somehow … we’ve grown to love that we think differently, to embrace it, and to affirm it with these interesting tests.
    (I think they’re fun too)

    NT: Now say again – you took a test about what … ?
    Aspie: Just a fun little test about cognitive recognition.
    NT: . . . why? …
    Aspie: Because it’s fun, and so interesting learning how you think about, react to, & assimilate information, and it can help you understand how you relate to things and people.
    NT: (with a frown face) … That’s just to much for me to think about.

    … lol

    1. I think some nonautistic people are into things like Meyers-Briggs testing or other tests that purport to find you the right career. A lot of high schools even make students take them as a “career prep” activity. I remember my daughter coming home and telling me that one of the options they recommended for her was minister, which was humorous because she’d been in a church maybe 5 times in her entire life up to that point.

      1. And some colleges too. In one of the many Microsoft Office and resume classes you get put through for just one degree, our teacher made us do a few online personality tests from varying websites. At the time I was surrounded by computer geeks and nerds, so we pretty much were all Introverted Intuitive/Sensing with varying combos on Thinking/Feeling and Judging/Perception. Most of my career matches were pretty good, but a pretty major miss when Sales popped up.

  8. I got Congruent 25.4, Incongruent 19.4. It must be the total time as it only took me seconds to answer each question. Certainly not 20+ seconds for each question – that’s quite a long time! I did get them all right though. I just looked at the words as shapes and didnt put the effort into decoding them into words.

  9. congruent: 5 13.476
    incongruent: 15 11.746

    I don’t think the scores can possibly be the mean (average). They might be the statistical variation. If I assume these scores are the variance and take the square root of the answers to get the standard deviation I get.

    congruent: 3.70
    incongruent: 3.42

    That’s possible. However I felt like I spent less than 30 seconds on the test. Just so happens I have a stopwatch app on my phone. I took it a second time and got similar results.

    congruent 5 13.736
    incongruent 15 11.885

    Seems I am not as mentally agile as I had pridefully believed, but I still completed the test in 34.9 seconds, and with the similar results, I am going to guess that I completed the first exam in similar time.

    The mean time it took me to answer a question on the second test (34.9/20) is 1.745 seconds. The deviations I calculated on the first test which will be almost identical on the second test seem to suggest that I answered some questions in roughly 0.4 seconds and one I struggled with most took me roughly 4.1 seconds to answer. Some questions did not require me to move the cursor and were even repeats. I probably did answer those in under 1/2 second. I do not recall struggling with anything for roughly 4 seconds, but again that could be pride clouding my recollection.

    I decided to test my internet latancy to the stroop test, so I pinged their server and found I have a small but noticable bit of lag, about 91 milliseconds. there is also possibly some hardware lag on their end, though this would be very minor unless the stroop test is hosted by a machine from 1999 with a Celeron processor (we have some at work….they still exist). The 91 ms ping could possibly account for why I feel that I didn’t spend quite that much time answering any one question.

    With the evidence I have gathered, I can absolutely determine that the stroop test scores are not the mean of the amount of the time it took to answer a question. I theorize that the statistic provided by the stroop test is the variance somewhat tainted by noticable latancy to their server. Not enough evidence or data to absolutely conclude that, but it holds weight.

  10. Huh, I found it very interesting to notice how difficult it actually was to disregard the meaning of the word itself! 🙂
    Congruent was 13.434 sec
    Incongruent 12.694 sec
    Second time was 11 and 9 sec. respectively, so slightly better. Funny how the congruent words apparently take longer. Because you’re double checking?
    And I love how many people in the comments have started analyzing the test itself 🙂

  11. Hmmm, I feel like the value of the Stroop Test decreases with practice.

    My first trial I was stupidly slow with everything, simply because it took me till nearly the end of the test to recognise that the options at the bottom were always in the same order (d’oh). The next time around, I was averaging 8 on the congruent and 7 on incongruent. Agree with RatherUnique that these results aren’t reflective of the average time per answer, as I pulled out a stopwatch and was sub two seconds on most responses. Maths isn’t my strong point, but general logic is ; )

    But there’s a Stroop Test game that’s part of Lumosity’s training plan (albeit with a much slicker interface), and I’ve been using it for years. Tracking my scores on there, I know I’ve improved dramatically over time, despite my (on average) abysmal executive functioning… I’ve effectively been trained in Stroop, like I’ve been trained to make eye contact, and not outwardly flinch when people hug me.

    1. I definitely think it decreases with practice and perhaps also with knowing the purpose and structure of the test in advance. When I took it at my evaluation, I had no idea what was coming next or what they were looking for in the results which made it harder to anticipate how I would need to adapt.

    2. “My first trial I was stupidly slow with everything, simply because it took me till nearly the end of the test to recognise that the options at the bottom were always in the same order (d’oh).”

      Yes! And on top of that, my biggest struggle was remembering which button was which. In my browser the button labels were laying out so the gaps between letters was weird and inconsistent so they didn’t even look the right shape.

  12. No significant time difference between congruant/incongruant, both about 20 seconds. Obviously, no mistakes. Only once, I was about to tick the wrong box. The difficulty was to move the cursor between the right answers, that’s where the time went. Even if by the end, I was nearly able to predict where I had to move the cursor. Nearly, though. I had to check every time to make sure I hit the right box.

    1. Thank you for writing that post and for participating. That missing campaign has turned into a PR disaster for A$ because the majority of the hashtag is now autistic people and their families refuting the horrible “missing” concept and calling on A$ to be more inclusive of autistic people and to put money into providing actual services.

  13. My husband is cracking up…apparently the phrase is “awesome sauce” – I get trendy phrases mixed up…Like at lunch I told my kids we will be doing chores like a well oiled ship. My husband laughed because apparently the phrase is actually “A well oiled machine”:)

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