Memory for two stimulus-response items in pigeons.

Skrtic et al. (1982) worked with pigeons on a two-item memory task. The birds first saw two color cues and had to pick the correct key for each.

After the second cue, a retention gap of 1, 3, 6, or 9 seconds passed before the test. The team watched how accuracy dropped as the gap grew.

Stimulus control fell apart quickly. By 9 seconds the pigeons were near chance, showing that even two simple links fade fast.

Changing the gap between the two items mattered less than the final wait before the test.

Bacon-Prue et al. (1980) ran almost the same task and also saw memory decay, but they stopped at 4 seconds and still saw fair accuracy. M et al. pushed the delay to 9 seconds and found the loss was steeper, so the two studies line up like early and late points on the same sliding scale.

Shimp et al. (1974) tested only one item and saw good recall up to 4 seconds. Adding a second item in M et al. doubled the load and the forgetting was faster, showing more content weakens memory.

Julià (1982) showed pigeons could remember their own peck counts for up to a minute. That seems to clash with the quick loss seen here, but the tasks differ: counting pecks used repeated cues during the delay, while M et al. left the birds with no hints, so both papers highlight the power of added cues.

When you teach conditional discriminations, keep the gap between prompt and response short. After about three seconds, stimulus control starts to slip, so insert quick practice trials or extra cues. If you must wait, give a brief model or prompt to bridge the fading memory.