Digit-Symbol Substitution 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.
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.
Measures: Processing speed, visual scanning, sustained attention, working memory, and symbol-digit paired-associate learning ability.
- Replaces and extends the previous PEBL 'letterdigit' task with additional functionality
- Supports both letters and Unicode symbols (─ ⊥ ⊐ ⌐ ∪ ○ △ ⋈ ≡) matching clinical DSST
- Four task modes: symbol→digit, digit→symbol, letter→digit, digit→letter
- Flexible input: keyboard for digit entry, clickable interface for symbol/letter entry
- Can operate in trial-count mode (default 30 trials) or timed mode (e.g., 2 minutes)
- Clinical DSST typically uses 2-minute time limit; default here is trial-count for consistency
- Includes 7 language translations: English, Spanish, French, German, Italian, Dutch, Portuguese
- Migrated to PEBL 2.3 with Layout system, LSL markers, and UploadFile support
| numtrials | Number of test trials (0 = unlimited, use timelimit instead). Clinical DSST uses 0 with timelimit=120 (default: 30) |
| usefeedback | Show feedback on all trials (always shown during practice) (default: 0) |
| stimulustype | Type of stimulus: letter (A-Z), symbol (DSST symbols), or mixed (default: symbol) |
| direction | Task direction: stimulus_to_digit (show stim, respond digit) or digit_to_stimulus (show digit, respond stim) (default: stimulus_to_digit) |
| inputmethod | Input method: keyboard (numbers only), click (clickable buttons), or auto (smart default) (default: auto) |
| timelimit | Time limit in seconds (0 = no limit, use numtrials instead). Clinical DSST/WAIS uses 120 seconds (2 minutes) (default: 180) |
| practicetrials | Number of practice trials (default: 5) |
| Validation | not-validated |
| Psychometric data | Not available |
| Normative data | Not available |
| 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 |