Short-term memory in the rhesus monkey: A behavioral analysis of delayed-response performance.
Letting a learner orient toward the correct item can be the self-cue that keeps delayed responding accurate.
01Research in Context
What this study did
Scientists worked with rhesus monkeys on a two-key delayed-response task.
The monkeys had to watch which key lit up, wait up to 20 s, then press that same key for food.
On some trials the team let the monkeys look at the correct key during the wait. On other trials they forced the animals to press a center key that blocked the view.
What they found
When monkeys could look at the food key, they scored above 85 % correct even at the longest delays.
Blocking the view by forcing a center-key press quickly hurt accuracy.
The earlier in the delay the view was blocked, the worse memory became.
How this fits with other research
Shimp et al. (1974) and Griffin et al. (1977) showed pigeons also keep short-lived stimulus-response links, but those birds used trained pecking patterns as memory aids instead of spontaneous looking.
Barber et al. (1977) found squirrel-monkey head turns and lever presses can be controlled separately; the new study shows that when looking is blocked, lever memory falls apart, proving the look is the glue.
Keller (1966) saw superstitious bar pressing when rat reinforcement was delayed; here, blocking the monkey’s natural orienting produced a similar drop in useful responding, linking delay problems across species.
Why it matters
Your learners may use subtle self-directed cues—eye shift, body lean, finger hover—to bridge brief gaps between instruction and response. If you block those cues with extra task steps, performance can crash even when the child “knows” the answer. Check for natural mediators before you add prompts or chains.
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Join Free →Before adding a prompt, watch the learner’s eyes and body during the delay; if they start to look away, gently block the distractor instead of adding a new motor step.
02At a glance
03Original abstract
This study obtained quantitative data on the bodily orientations of rhesus monkeys in a delayed-response task and determined whether such orientations mediate the correct response in a choice trial. The basic task was a two-key chain schedule with the key leading to food signaled in the initial component. During the subsequent delay interval, the signal was removed, but it was necessary that one of the keys be pressed to advance the schedule to the terminal choice component. The position of the key pressed thus indicated orientation during the delay interval. When the monkeys had free access to the left and right keys, they tended to press the key leading to food throughout the chain schedule components and received food on more than 85% of the trials, even when the delay was extended to 20 seconds. However, when orientation toward the food key was disrupted by forcing the monkeys to press an extraneous center key during the delay, choice performance deteriorated. Requiring the center key presses early, rather than late, in the delay component had a strong disruptive effect. The relation of the results to the mediating coding-response hypothesis is discussed.
Journal of the experimental analysis of behavior, 1980 · doi:10.1901/jeab.1980.33-359