Stimulus control of responding during a fixed-interval reinforcement schedule.
A stimulus can speed or slow behavior in the same session — the recent reinforcement zone decides which.
01Research in Context
What this study did
Rats pressed a lever on a fixed-interval 60-s schedule. A light came on at different points in the interval. The team recorded how the light changed response rate.
They wanted to see if the same light would help or hurt pressing at different times.
What they found
Late in the interval the light sped pressing. Early in the interval it slowed pressing, but only after the rat had earned food in that early zone.
Same light, opposite effect — the schedule history flipped the stimulus control.
How this fits with other research
Hendry et al. (1969) showed that earlier noise training can block a new light from controlling behavior. Baer (1974) adds the next layer: once control exists, it can switch direction.
Burgess et al. (1971) found that mixing two rate signals gives a middle rate. Baer (1974) shows the signal itself can mean 'go' or 'stop' depending on past payoff.
Davison et al. (1991) later showed these basic rules even work in horses, so the conditional control seen here is not just a rat quirk.
Why it matters
When you use a timer, picture card, or tone during DRO, DRL, or FI sessions, remember that its power to help or inhibit depends on when the client last got reinforced. If you see odd spikes or drops, check the timing history before you switch cues. You might keep the same stimulus and just rearrange the payoff zones.
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02At a glance
03Original abstract
During training sessions, pecks by pigeons on a response key illuminated by a vertical line of white light resulted in reinforcement and an ensuing blackout according to a fixed-interval schedule. Training sessions were followed by dimensional stimulus control test sessions during which the orientation of the line present throughout the fixed interval was varied. Inverted U-shaped (excitatory) gradients of responding, with maximum responding occurring in the presence of the vertical line, were observed during the terminal part of the fixed interval. U-shaped (inhibitory) gradients of responding, with minimum responding occurring in the presence of the vertical line, were observed during the early part of the fixed interval when the preceding interval had terminated with reinforcement and blackout but not when the preceding interval had terminated with blackout only. These results suggest that the dimensional control by the stimulus present throughout the fixed interval is of a conditional variety. Whether the fixed-interval stimulus exerts inhibitory or excitatory dimensional control depends upon the presence and absence, respectively, of stimuli associated with reinforcement.
Journal of the experimental analysis of behavior, 1974 · doi:10.1901/jeab.1974.21-425