PEBL Hub — IRB Fact Sheet — 2026-08-23
Pattern Comparison (Same/Different)
Processing Speed
Perception
Category:Processing Speed
Duration:~5 minutes
Parameters:7 configurable parameters available
Version:1.0
Description
A go/no-go pattern comparison task where two dot patterns are presented simultaneously and participants press the spacebar if they match the target condition.
Two dot grid patterns are displayed side by side. In the first block, participants press the spacebar if the patterns are the SAME (withhold if different). In the second block, the rule reverses: press if DIFFERENT (withhold if same). Each trial has a response deadline. Measures speed and accuracy of simultaneous pattern comparison.
Measures: Visual pattern comparison, processing speed, go/no-go inhibition
Key Parameters
| similarfoil | should foil be similar to target (default: 1) |
| foildiff | Number of changes between target and foil (default: 3) |
| size | size of the target/foil matrices (default: 4) |
| givefeedback | Whether to give feedback (default: 1) |
| condsize | Number of trials per condition (x12) (default: 10) |
| deadline | Time in ms to give a response (default: 1500) |
| responsemode | Response mode: spacebar, leftclick, touchscreen, clicktarget, userselect (default: spacebar) |
Data Output Columns
| subnum | Participant ID |
| trial | Trial number within the current block |
| samediff | Whether the two patterns were the same or different (same/diff) |
| cond | Response condition for the current block (s=press spacebar if same, d=press spacebar if different) |
| delta | Number of dot position differences between patterns (0 for same trials; 1, 2, or 3 for different trials) |
| mat1 | Left pattern encoded as a binary string (1=dot present, 0=empty) |
| mat2 | Right pattern encoded as a binary string |
| abstime | Absolute timestamp in milliseconds from the start of the test |
| rt | Response time in milliseconds from stimulus onset (equals deadline if no response) |
| resp | Whether participant responded (respond) or withheld (timeout) |
| corr | Whether the response was correct (1) or incorrect (0) |
References
Perez, W. A., Masline, P. J., Ramsey, E. G., & Urban, K. E. (1987). Unified tri-services cognitive performance assessment battery: Review and methodology. DTIC/TR-87-007.
Mueller, S. T. (2011). The PEBL Pattern Comparison Task. Computer software retrieved from http://pebl.sf.net/battery.html