Digit-Symbol Substitution Test
System Requirements
Minimum: 1024×768
Recommended: 1280×800
Description
A processing speed and associative learning task requiring participants to match symbols with digits or letters with digits using a mapping key displayed on screen.
About This Test
Participants view a mapping of symbols or letters paired with digits (1-9) at the top of the screen. On each trial, a stimulus appears in the center, and participants must respond with the corresponding digit (or vice versa). The task supports four directional modes: (1) symbol→digit (DSST forward), (2) digit→symbol (DSST reverse), (3) letter→digit (classic PEBL letterdigit), (4) digit→letter. Input can be via keyboard or clickable button interface (required for symbol/letter responses). This implements an enhanced version of the previous PEBL letterdigit task with expanded functionality.
Test Details
digitsymboldigitsymbol.pbl🚀 Try Without Registration
Run this test immediately without creating an account. Data stays in your browser.
Researcher Access Benefits
To save configurations, upload data, use translations, track completion, and manage studies, please log in or register for an account.
Scientific Background
Original Task References:
These references describe the original task that this PEBL implementation is based on.
- Wechsler, D. (1981). WAIS-R manual: Wechsler adult intelligence scale-revised. Psychological Corporation.
- Lezak, M. D., Howieson, D. B., Bigler, E. D., & Tranel, D. (2012). Neuropsychological assessment (5th ed.). Oxford University Press.
Data Output
Creates two data files: (1) digitsymbol-<subnum>.csv with trial-by-trial data including stimulus type, direction, response mode, accuracy and reaction time; (2) digitsymbol-summary-<subnum>.txt with overall performance statistics.
Example Data
digitsymbol-example.csv Primary
Trial-by-trial data with columns: subnum (participant code), stimtype (letter/symbol), direction (stimulus_to_digit or digit_to_stimulus), inputmethod (keyboard/click/auto), block (0=practice, 1=test), trial (trial number), probe (stimulus presented), cresp (correct response), resp (participant response), corr (accuracy: 1/0), rt (response time in ms)
| subnum | stimtype | direction | inputmethod | block | trial | probe | cresp | resp | corr | rt |
|---|---|---|---|---|---|---|---|---|---|---|
| 111 | symbol | stimulus_to_digit | auto | 0 | 1 | △ | 7 | 7 | 1 | 5016 |
| 111 | symbol | stimulus_to_digit | auto | 0 | 2 | ∪ | 5 | 5 | 1 | 2949 |
| 111 | symbol | stimulus_to_digit | auto | 0 | 3 | ≡ | 9 | 9 | 1 | 1359 |
| 111 | symbol | stimulus_to_digit | auto | 1 | 1 | ∪ | 5 | 5 | 1 | 4012 |
| 111 | symbol | stimulus_to_digit | auto | 1 | 2 | ─ | 1 | 1 | 1 | 1137 |
| 111 | symbol | stimulus_to_digit | auto | 1 | 3 | ─ | 1 | 1 | 1 | 635 |
| 111 | symbol | stimulus_to_digit | auto | 1 | 4 | ∪ | 5 | 5 | 1 | 1495 |
| 111 | symbol | stimulus_to_digit | auto | 1 | 5 | ∪ | 5 | 5 | 1 | 2116 |
| 111 | symbol | stimulus_to_digit | auto | 1 | 6 | ⋈ | 8 | 8 | 1 | 1334 |
digitsymbol-summary-example.txt Summary
Text summary report containing: test metadata, participant code, stimulus-digit mapping, total trials, number correct, proportion correct, mean/median/min/max RT, RT range, standard deviation and variance
---------------------------------------------- PEBL Digit-Symbol Substitution Test (DSST) Version 2.0 Released into public domain 2008-2026 by Shane T. Mueller, Ph.D. Sat Jan 31 12:21:49 2026 PEBL Version 2.3 ---------------------------------------------- Participant code: 111 Stimulus type: symbol Direction: stimulus_to_digit Input method: auto ---------------------------------------------- Mapping: ─ → 1 ⊥ → 2 ⊐ → 3 ⌐ → 4 ∪ → 5 ○ → 6 △ → 7 ⋈ → 8 ≡ → 9 ---------------------------------------------- Number of trials: 13 Number correct: 13 Proportion correct: 1 Percent correct: 100% Mean RT: 1848 ms Median RT: 1652 ms Min RT: 635 ms Max RT: 4012 ms RT Std Dev: 813 ms ----------------------------------------------
Sample data showing typical output format. Actual values will vary by participant.
About This Test
A processing speed and associative learning task requiring participants to match symbols with digits or letters with digits using a mapping key displayed on screen.
Category: Processing Speed
Estimated Duration: 5 minutes
Available Translations: 7 languages
Documentation Sources:
Test description file, Test implementation, Parameter schema
Documentation Status: Complete