This test measures your familiarity with small quantities of objects, also known as subitizing. Fast counting of larger numbers of objects is more of a pattern matching task, and less of subitizing -- this test will not give you the ability to count 40 people in one glance!

This test would be familiar to anybody with elementary musical training, and should be reasonably quick to learn for untrained ears. It is meant to be a precursor to a later test that will require quick differentiation between tones.

The flanker test is another interference task where different inputs compete with the target, slowing down the response speed. This is a basic variant using arrows: identify the direction of the CENTER arrow as fast as you can. Estimated completion time: less than 1 minute per session. (test added following suggestion from an anonymous user).

Variant of the classic Stroop Test. Dissonance between the color presented and the mismatched name interferes with naming the color. The Stroop Test causes elevated activation in the anterior cingulate cortex, which is involved in detecting the incongruity.

Variant of a simple, non-auditory digit span test. The digit span is often used to measure short-term memory via the phonological loop. The objective is to remember as many digits as possible. The expected average is around 7 digits for the untrained; trained individuals can reach well above 60 digits. Common techniques include the method of loci, mnemonics, and plain association; at this point, longer-term memory processes become involved in task performance.

The same task as the forward digit span, done in reverse. This means when answering, you need to type the digits in the reverse order in which you saw them. Just as you probably thought, this is a harder task than the forward digit span, as it requires manipulation of items in the working memory, requiring a greater role of the executive functions. Normally, your backwards digit span will be a few less than your forward digit span, along with an expected slowdown of response time. How much slower?

The simple digit span test, administered by sound, in English. As this task usually depends on the phonological loop, it is similar to the first digit span test, except 1. there is no visual co-/activation, 2. there is no conversion of memory modality (visual to auditory), 3. it forces you to think in English, at least at the comprehension stage, which may put those who count in non-English languages at a disadvantage. Is there a difference? See for yourself.

Same as the visual reverse digit span, but presented auditorily in English. You will have to respond with the digits you heard, but backwards.

This a variation of an item span test using letters; it is deliberately made to give you a hard time using the phonological loop. There are no vowels, all the letters are presented at the same time, and they will appear for less than half a second.

Variant of the Corsi block tapping test, which requires you to remember and reproduce a sequence of block positions. This test would be the visuospatial analogue to the digit span test. Thanks to Sherif

Reproduce the displayed block sequence in reverse; visuospatial analogue of the reverse digit span task.

Variant of the consonant span task where you have to choose the correct answer from three distractors. Like the consonant span, this test is aimed to test character recognition and memory with limited phonological activation.

Modified version of the Jaeggi-Buschkuehl dual n-back test using a phonology closer to combinations of /k p s t/ and /a i u/. Spelled in English, the sounds will resemble "kee, pee, soo, taa," etc. The stimuli are selected probabilistically.

Flash-based variant of the dual n-back test using a visual+auditory paradigm as detailed in S.M. Jaeggi et al.'s paper, Improving fluid intelligence with training on working memory. This test simultaneously presents visual and auditory stimuli, and will dynamically change difficulty based on past performance, so take note of the title before beginning. Requires speakers/headphones.

This is a variant of what is known as the "n-back task," a test useful for investigating working memory. Try using the 2-back option first, then move higher up. This version was capped at 7-back, which should be very difficult for most people. As some users have gotten used to it, it is now capped at n = 9.

Variant of the Paced Auditory Serial Addition Task (PASAT). The objective is to sum up the last n numbers shown before the time runs out. This requires sustained attention as well as executive functions (cingulate, prefrontal, temporal, parietal areas -- will follow up). There is some correlation between IQ and PASAT performance; indeed, as the mechanisms are similar to the n-back task, PASAT performance is also correlated to n-back task performance. A dual-modality PSAT setup would be analogous to the dual n-back. This test begins at PASAT-2, and is self-adjusted. Please view the demonstration before you begin.

This is an n-back task that presents only the visual portion used in the earlier dual n-back tasks. It is here for you to compare performance with the dual n-back task. This test is NOT self-adjusting.

This is a single n-back task that presents only the German version of the auditory stimuli used in the J-B dual n-back task. It is here for you to compare performance with. This test is NOT self-adjusting.

A single modality n-back task that uses the auditory stimuli of the kpst dual n-back task; the timings are kept the same. Take this test for comparison. This test is NOT self-adjusting.

An implementation of the reading span task based on the seminal work, Individual Differences in Working Memory and Reading (Daneman and Carpenter, 1980). RST variants are commonly used to test working memory capacity as well as reading comprehension ability. RST performance is also moderately correlated with Verbal SAT performance. The D&C RS average is around 3.15 (this should be slightly above a general population average).

A multimodal n-back task designed to be resistant to chunking effects by maintaining sufficient novelty. Choose different combinations of visual and auditory stimuli, with three input options (auditory, spatial, visual). A Flickr option is available as a visual source -- along with the links -- for a bit of photo discovery fun! There is currently no demonstration; familiarity with other dual tasks (see J-B dual n-back) is required.

This is a follow-up test to the previous PASAT after the time limit was made slower. This test speeds up when you answer correctly, and slows down when you miss. You must answer before the input box disappears completely.

This is a dual n-back task variant that adjusts the stimulus presentation speed based on immediate feedback. That is, the better you perform, the faster it goes. It is also an attempt to make the dual n-back test entertaining. Gameplay is largely a reproduction of Damien Clark's Missile Game 3D. This test is still highly experimental and is likely to change. To read about the test concepts and design principles, please check out the blog. If you take this test, please watch the demonstration; you are guaranteed to be confused otherwise. This test is NOT intuitive.

Remember where the dots are, and follow their location as they move around the cell as indicated by the arrows. This test is very loosely based on the spatial memory test in Linking Cognitive and Cerebral Aging by Salthouse, Babcock, and Shaw (1991).