Stimulus functions in chained fixed-interval schedules.
The look and order of cues, not just the clock, decide how behavior moves through chained fixed-interval schedules.
01Research in Context
What this study did
The team built a chain of fixed-interval schedules. Each link had its own colored light.
The order of the lights changed across sessions. Everything else stayed the same.
They watched how the birds pecked when the cue order, not the timing, was switched.
What they found
New light sequences created new peck patterns. Same clock, different dance.
The birds paused, sped up, or slowed down to match the new cue order.
Stimuli, not just seconds, controlled when and how fast they responded.
How this fits with other research
FARMEMOORHEARSKELLEHER et al. (1964) later added a DRL rule to FI. Response rate dropped, but the pause stayed.
Thomas (1968) broke FI rate into mini-parts. The 1962 study shows one reason: cues mark each part.
Austin et al. (2015) let the bird’s own peck start the interval. Timing got sloppy without outside cues.
Together, the four papers say: external cues sharpen FI performance; remove or shuffle them and behavior drifts.
Why it matters
Your client on a DRO or FI schedule needs clear, steady signals. Swap the order or drop a cue and the old pattern can fall apart. Keep the stimuli consistent, or retrain when you must change them.
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02At a glance
03Original abstract
Pigeons were required to complete three successive fixed-interval components to obtain food. When the same exteroceptive stimulus was correlated with the three components, responding was positively accelerated between food deliveries. When different exteroceptive stimuli were correlated with each component in a fixed sequence, prolonged pauses developed in the first component; low response rates developed in the second component; and responding was positively accelerated in the second and third components. When different exteroceptive stimuli were correlated with each component in a variable sequence, responding was positively accelerated in each component. Because the response and reinforcement contingencies were the same in all three procedures, the differences in performances must be due to the changes in the sequence of stimuli.
Journal of the experimental analysis of behavior, 1962 · doi:10.1901/jeab.1962.5-167