Autoshaping the pigeon's gape response: acquisition and topography as a function of reinforcer type and magnitude.
In autoshaping the earliest signal of learning is often an invisible mouth movement, and its size directly reveals how much the reinforcer is worth.
01Research in Context
What this study did
The team worked with pigeons in an autoshaping set-up. A lit key always came before grain.
They compared big grain piles, small piles, grain versus water, and short versus long access.
Birds wore tiny sensors that tracked when the beak opened and how wide it went.
What they found
The gape response showed up first and happened far more often than actual key pecks.
Bigger or tastier reinforcers made the birds open wider and reach faster.
Water or tiny grain produced smaller, slower beak movements.
How this fits with other research
Ploog et al. (1997) later saw the same thing under a choice schedule: food still produced the wide, fast gape and water the small one.
Parsons et al. (1981) had earlier warned that long gaps between key-light and grain weaken key pecking; W et al. now show the gape itself still forms quickly, so topography is sturdier than rate.
Duncan et al. (1972) first split the key peck into two types with different force; W et al. add that even within one type, reinforcer size keeps sculpting the form.
Why it matters
If you run autoshaping or pairing procedures, watch the first subtle motor sign—it may outrun the main response and tell you if the reinforcer is strong enough. When the client’s micro-response looks weak, try a bigger or preferred reinforcer before you blame the contingency.
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02At a glance
03Original abstract
The pigeon's key-pecking response is experimentally dissociable into transport (head movement) and gape (jaw movement) components. During conditioning of the key-pecking response, both components come under the control of the conditioned stimulus. To study the acquisition of gape conditioned responses and to clarify the contribution of unconditioned stimulus (reinforcer) variables to the form of the response, gape and key-contact responses were recorded during an autoshaping procedure and reinforcer properties were systematically varied. One group of 8 pigeons was food deprived and subgroups of 2 birds each were exposed to four different pellet sizes as reinforcers, each reinforcer signaled by a keylight conditioned stimulus. A second group was water deprived and received water reinforcers paired with the conditioned stimulus. Water- or food-deprived control groups received appropriate water or food reinforcers that were randomly delivered with respect to the keylight stimulus. Acquisition of the conditioned gape response frequently preceded key-contact responses, and gape conditioned responses were generally elicited at higher rates than were key contacts. The form of the conditioned gape was similar to, but not identical with, the form of the unconditioned gape. The gape component is a critical topographical feature of the conditioned key peck, a sensitive measure of conditioning during autoshaping, and an important source of the observed similarities in the form of conditioned and consummatory responses.
Journal of the experimental analysis of behavior, 1994 · doi:10.1901/jeab.1994.62-201