Serial conditioning as a function of stimulus, response, and temporal dependencies.
Stimulus-food pairings alone can create FI-like curves, so the clock may matter more than the response rule.
01Research in Context
What this study did
Cohen et al. (1990) worked with pigeons in a small lab space. The birds saw a chain of colored lights that always ended with food, no matter what they did.
The team never asked the birds to peck. They only checked if the birds still showed the curved "scallop" pattern seen on fixed-interval schedules.
What they found
The pigeons pecked anyway, and their rates curved up just like on a fixed-interval schedule. Stimulus-food links alone drove the pattern.
Response requirement and fixed interval length were not needed to make the scallop.
How this fits with other research
Whitehead et al. (1975) saw flattened curves when they removed the peck-food link on true FI schedules. Cohen et al. (1990) removed the link again but added serial stimuli and still got the curve. The stimuli, not the schedule, restored the pattern.
Byrd (1972) kept only 7% of intervals with food and still saw scalloping. L et al. (1991990) drop the contingency to zero and keep the curve, showing the effect is even stronger than D thought.
Neef et al. (1986) found birds tried to escape early chain stimuli. Cohen et al. (1990) show those same stimuli can also build steady work, so escape and scalloping live side by side in serial chains.
Why it matters
If you run FI or chained programs, check whether the child's work pattern comes from the response rule you set or just from the stimulus clock ticking toward reinforcement. When you want to test true response control, strip the stimuli or change their order and watch what stays.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Run one probe session with the same timing but no response requirement and see if the learner's pattern stays the same.
02At a glance
03Original abstract
Six experiments were used to examine the effects of explicit response, stimulus, and temporal dependencies on responding in an interfood interval. The first two experiments demonstrated that 10-segment 60-s interfood clocks controlled similar distributions of key pecking in pigeons regardless of whether response-reinforcement contiguity was required, allowed, or precluded. The third and fourth experiments found that in the absence of an explicit response-reinforcement dependency, systematic explicit stimuli in an interfood interval were sufficient to establish and maintain the characteristic distribution of key pecking and that an interval without an explicit clock failed to establish or maintain key pecking. The last two experiments demonstrated that the interfood interval need not be of fixed length, and that a simple correlation of stimuli with increments from either a minimum to a maximum imminency or probability of food presentation controlled behavior in a similar manner. Successively higher rates generally occurred to successively later stimuli in the upper half of the range.
Journal of the experimental analysis of behavior, 1990 · doi:10.1901/jeab.1990.53-65