Line Judgment Task
Description
A speed-accuracy tradeoff task based on Henmon (1910) where participants quickly discriminate which of two vertical lines is longer under varying deadline conditions.
Measures: Speed-accuracy tradeoff in visual discrimination, perceptual judgment under time pressure, and the relationship between response time constraints and decision accuracy.
Processing Speed Perception Visuospatial
Ages: 7+ · Populations: adults, children, research, clinical
About This Test
Participants view two vertical lines (one on the left, one on the right) and must judge which is longer before a visual timer expires. The task consists of multiple blocks with progressively shorter response deadlines (default: 10000ms, 2000ms, 1000ms, 700ms, 500ms), creating an increasingly difficult speed-accuracy tradeoff. Each block includes practice trials followed by experimental trials with balanced sampling of line length differences. A red timer bar animates to show remaining response time.
- Migrated to PEBL 2.3 Layout & Response System on January 12, 2026
- Supports 8 response modes for multi-platform deployment
- Includes 7 language translations: English, Spanish, French, German, Italian, Dutch, Portuguese
- Uses semantic response labels ('left'/'right') instead of raw key codes
- Timer animation can be disabled via usetimer parameter while maintaining deadline enforcement
- Default configuration uses 5 deadline blocks with progressively shorter time limits
Test Details
linejudgmentlinejudgment.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.
- Henmon, V. A. C. (1911). The relation of the time of a judgment to its accuracy. Psychological Review, 18(3), 186-201.
Validation status: Not-validated
Related Tests
Data Output
Creates two data files: (1) linejudgment-data-<subnum>.csv with trial-by-trial data; (2) linejudgment-report-<subnum>.txt with block-level summary statistics including accuracy rates and mean response times.
Key Variables
| Variable | Description |
|---|---|
| subnum | Participant identifier code |
| block | Block number (1-5 depending on numblocks parameter) |
| trial | Cumulative trial number across all blocks |
| blocktrial | Trial number within block (P=practice trials, 1-N for experimental trials) |
| deadline | Response time limit for the block in milliseconds |
| usetimer | Whether animated timer was shown (0=off, 1=on) |
| l1, l2 | Lengths of the two lines in pixels |
| x1, y1, x2, y2 | Screen positions of the two lines (x,y coordinates) |
| toolong | Whether response exceeded deadline (1=timeout, 0=responded in time) |
| resp | Semantic response: 'left', 'right', or '<timeout>' |
| corr | Response accuracy (1=correct, 0=incorrect) |
| rt | Response time in milliseconds |
| time0 | Absolute trial start time in milliseconds |
Example Data
| subnum | block | trial | blocktrial | deadline | usetimer | l1 | l2 | x1 | y1 | x2 | y2 | toolong | resp | corr | rt | time0 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| P-mkc14c8b-q8ge | 1 | P | P | 10000 | 1 | 110 | 120 | 919 | 498 | 999 | 487 | 0 | right | 1 | 2085 | 23783 |
| P-mkc14c8b-q8ge | 1 | P | P | 10000 | 1 | 120 | 110 | 918 | 490 | 999 | 495 | 0 | right | 0 | 1861 | 26397 |
| P-mkc14c8b-q8ge | 1 | P | P | 10000 | 1 | 110 | 111 | 920 | 493 | 1001 | 496 | 0 | left | 0 | 1628 | 28789 |
| P-mkc14c8b-q8ge | 1 | P | P | 10000 | 1 | 120 | 119 | 920 | 489 | 1000 | 491 | 0 | left | 1 | 900 | 30937 |
| P-mkc14c8b-q8ge | 1 | 1 | 1 | 10000 | 1 | 116 | 115 | 919 | 489 | 999 | 495 | 0 | left | 1 | 678 | 32358 |
| P-mkc14c8b-q8ge | 1 | 2 | 2 | 10000 | 1 | 118 | 112 | 919 | 495 | 998 | 490 | 0 | left | 1 | 813 | 33558 |
| P-mkc14c8b-q8ge | 1 | 3 | 3 | 10000 | 1 | 113 | 120 | 918 | 497 | 1002 | 486 | 0 | right | 1 | 1135 | 34892 |
| P-mkc14c8b-q8ge | 1 | 4 | 4 | 10000 | 1 | 120 | 110 | 919 | 485 | 1000 | 500 | 0 | left | 1 | 649 | 36555 |
| P-mkc14c8b-q8ge | 1 | 5 | 5 | 10000 | 1 | 117 | 112 | 918 | 494 | 1001 | 491 | 0 | left | 1 | 605 | 37735 |
Sample data showing typical output format. Actual values will vary by participant.
About This Test
A speed-accuracy tradeoff task based on Henmon (1910) where participants quickly discriminate which of two vertical lines is longer under varying deadline conditions.
Category: Processing Speed
Estimated Duration: 10 minutes
Available Translations: 7 languages
Documentation Sources:
Test description file, Test implementation, Parameter schema
Documentation Status: Complete