Line Judgment Task
A speed-accuracy tradeoff task based on Henmon (1910) where participants quickly discriminate which of two vertical lines is longer under varying deadline conditions.
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.
Measures: Speed-accuracy tradeoff in visual discrimination, perceptual judgment under time pressure, and the relationship between response time constraints and decision accuracy.
- 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
| numtrials | Number of trials per deadline condition. (default: 15) |
| usetimer | Whether to use the red visual timer. Timeout still occurs; it just in't animated. (default: 1) |
| offset | Number of pixels offset from midline each line is presented (give-or-take a small amount of jitter). (default: 40) |
| numblocks | Number of parameter-specified deadline blocks to use. Can be no larger than 5. (default: 5) |
| deadline1 | Deadline for first block (default: 10000) |
| deadline2 | Deadline for second block (default: 2000) |
| deadline3 | Deadline for third block (default: 1000) |
| deadline4 | Deadline for fourth block (default: 700) |
| deadline5 | Deadline for fifth block (default: 400) |
| minlength | Minimum pixel size for line (default: 110) |
| maxlength | Maximum pixel size for line (default: 120) |
| responsemode | Response mode: auto (platform-aware), keyboardShift, keyboardSafe, arrowLR, userselect (user-selected keys), mousetarget, mousebutton, touchtarget (default: auto) |
| Validation | not-validated |
| Psychometric data | Not available |
| Normative data | Not available |
| 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 |