Processing speed test: method

What it measures

Processing speed, with contributions from visual scanning, learning of the symbol–digit pairs and motor speed.

Procedure

A key on screen pairs 9 symbols (drawn for each run from 12 original symbols) with the digits 1 to 9; the key stays visible. One symbol at a time; the player enters its digit with an on-screen number pad or the keys 1 to 9. Every answer, right or wrong, moves on to the next symbol at once. The same digit never comes twice in a row. 6 practice symbols with feedback (600 ms); new players get practice by default, everyone can skip it. Then 90 seconds of counted symbols. Leaving the browser tab ends the run.

Parameters

Scoring

Score = number of correct answers within the time; higher is better. Also: answers given, errors (answers minus correct) and time per correct answer = 90 s / correct answers. No player comparison is shown.

Valid-run rules

The server regenerates the key and the symbol order from the run's seed and matches answers to symbols by position. Answer times must not go backwards; answers after 91.5 s do not count. The server rebuilds every run from the raw log (and the run's seed where there is one) and computes the score itself; anything the page says about right or wrong is ignored. A log that breaks the game's rules is rejected, and nothing is stored. Stored runs can carry quality flags that are never shown and never block a result: 10 or more runs from one IP address, a missing visitor id, tab switches, and automation signals (automated browser, impossible speed, no input events, machine-regular timing).

Differences from the classic task

The Symbol Digit Modalities Test uses a fixed key and a printed page of symbols, 90 seconds, and oral or written answers, with published norms; the Wechsler Coding subtest asks people to write symbols for digits. Here the symbols are our own, the pairing changes every run, symbols come one at a time and answers are key presses or taps. No norms.

Limitations

Keyboard versus touch input changes speed a lot. Scores rise over the first runs as the task becomes familiar. Unsupervised browser setting. Not a clinical test; results say nothing about health.

Languages and review status

Language-independent stimuli, instructions in all site languages (English plus 99 other languages). The key reads left to right (1 to 9) in every language.