PEBL Hub — IRB Fact Sheet — 2026-10-07
Brown-Peterson Task
Memory
Processing Speed
Category:Memory
Duration:~15 minutes
Parameters:15 configurable parameters available
Version:1.0
Description
A short-term memory task where participants memorize consonant trigrams and recall them after a distractor-filled delay.
On each trial, three consonants (a CVC trigram) are briefly displayed, followed by a three-digit number. Participants count backward by 3s from the number in time with auditory/visual cues for varying delay intervals (3-18 seconds). After the delay, participants recall the original consonants. Accuracy typically declines with longer delays, demonstrating rapid forgetting from short-term memory.
Measures: Short-term memory, decay of short-term memory traces, interference effects
Key Parameters
| usebeep | (default: 1) |
| reps | (default: 8) |
| repsintrial | (default: 1) |
| beeptime | Beep time for counting, in ms. (default: 500) |
| numdelays | Number of distinct delays to use. Up to ten are possible. Relevant delays delay1..delay10 will be used. Default values are ones used by Peterson & Peterson, 1959. (default: 6) |
| delay1 | Time in seconds of first delay (default: 3) |
| delay2 | Time in seconds of 2nd delay (default: 6) |
| delay3 | Time in seconds of 3rd delay (default: 9) |
| delay4 | Time in seconds of 4th delay (default: 12) |
| delay5 | Time in seconds of 5th delay (default: 15) |
| delay6 | Time in seconds of 6th delay (default: 18) |
| delay7 | Time in seconds of 7th delay (default: 0) |
| delay8 | Time in seconds of 8th delay (default: 0) |
| delay9 | Time in seconds of 9th delay (default: 0) |
| delay10 | Time in seconds of 10th delay (default: 0) |
Scoring & Interpretation
The key dependent variable is accuracy as a function of delay. The classic finding (Peterson & Peterson, 1959) shows rapid decay: near-perfect recall at 3s dropping to near-chance by 18s. The HTML report provides accuracy and response time broken down by delay interval. Geometric mean RT is used because RT distributions are typically right-skewed.
Example Data Output (5 sample rows)
| subcode | trial | ccc | number | delay | resp | corr | rt |
|---|---|---|---|---|---|---|---|
| example | 1 | TRB | 288 | 9 | TRB | 1 | 2273 |
| example | 2 | CJK | 858 | 6 | CJK | 1 | 2799 |
| example | 3 | RGH | 337 | 3 | RGH | 1 | 3137 |
| example | 4 | KDT | 893 | 9 | CRG | 0 | 7525 |
| example | 5 | NDZ | 446 | 6 | NDZ | 1 | 13207 |
References
Peterson, L. R., & Peterson, M. J. (1959). Short-term retention of individual verbal items. Journal of Experimental Psychology, 58(3), 193-198.
Mueller, S. T. (2011). The PEBL Brown-Peterson Task. Computer software retrieved from http://pebl.sf.net/battery.html