Operant control of response latency in monkeys: evidence for a central explantation.
Reinforcement can sculpt millisecond-perfect timing, proving even brief pauses are operant responses you can shape.
01Research in Context
What this study did
Two monkeys pressed a button for food. The catch: they only got food if they pressed within a 50-millisecond window.
The window could sit anywhere from 200 to 600 ms after a light came on. The team moved the window around to see if the monkeys could hit the new sweet spot.
What they found
The animals learned to park 60-80 % of their presses inside any 50 ms band the experimenters set.
That level of millisecond control shows timing is not a reflex; it is an operant response that can be shaped.
How this fits with other research
Sanders et al. (1971) later used the same monkey lab and showed auditory location can be brought under equally fast control, stretching the 1968 timing idea to a new sense.
Rutter et al. (1987) and Pinheiro de Carvalho et al. (2012) moved the work to pigeons and the bisection task; they found reinforcers still govern timing, but the birds rely on absolute, not relative, cues.
Johnson et al. (2009) flipped the coin: instead of shaping latency, they used naturally short latencies to spot high-risk demands in kids’ functional analyses. Same metric, opposite aim.
Why it matters
If monkeys can learn to hit a 50 ms window, your learners can master any time-based skill: waiting two seconds before answering, pressing for exactly one second, or pausing before transitions. Start with wide reinforcement windows and shrink them gradually; the study shows timing will tighten right up.
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02At a glance
03Original abstract
Two monkeys (M. mulatta) were trained to press a telegraph key after onset of a tone and release it quickly in response to a subsequent light or click stimulus occurring after a variable interval. After training first with a fixed time limit on response latency for key release and then with a continuously adjusting limit, reaction time to click was 160 msec and to light, about 200 msec. Temporal contingencies or "payoff bands" were then introduced which reinforced only responses with latencies which fell between two limits 50 msec apart. Feedback was given as to whether each latency was too slow, within the band, or too fast. A trained monkey could precisely center its latency distribution on any 50 msec-wide payoff band located from 200 to 600 msec after the stimulus, with from 60 to 80% of its responses achieving reinforcement. Distribution statistics were comparable to those of trained human subjects. Because such precise timing might be accomplished by a peripheral adjustment, such as changing the manner of holding the key, latency of electromyographic activation was measured in participating arm muscles in one monkey. Electromyographic activation preceded key release by a constant interval, regardless of response latency, indicating a more central mechanism for timing of brief intervals.
Journal of the experimental analysis of behavior, 1968 · doi:10.1901/jeab.1968.11-89