The use of rats as discriminative stimuli.
Even a rat can treat another rat as a discriminative stimulus—so always check what stimulus control you’re actually establishing.
01Research in Context
What this study did
Four rats worked in a cage. A second rat was either present or absent. The rats learned to press a lever only when the partner rat was there.
Later the task flipped. Now they pressed only when the partner was absent. Each rat mastered both rules.
What they found
Every rat learned both discriminations. The partner rat itself became the cue that controlled pressing.
A live animal can work like a traffic light: its presence or absence can turn behavior on and off.
How this fits with other research
Tracey et al. (1974) moved the idea to pigeons and pictures. They showed that birds pick out the unique part of a compound image, extending the rat work to visual features.
Siegel et al. (1970) pushed further. Pigeons formed a broad "person-present" concept that transferred to new people, showing abstract stimulus control beyond a single rat.
Okouchi (1999) tested humans. Instructions acted as cues, but control was weaker and mixed across subjects. Same principle, softer effect.
Why it matters
If a rat can treat another rat as a cue, your learner can treat anything as a cue: your face, the chair, the smell of coffee. Check what is really steering the response. When you want clean stimulus control, strip the room to the one cue that matters.
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02At a glance
03Original abstract
A FREE OPERANT PROCEDURE WAS USED TO DETERMINE WHETHER OR NOT ONE RAT COULD DISCRIMINATE: (1) between the presence and absence of a second rat, and (2) between two other rats of the same species and sex. The subjects were four male Wistar rats. The discriminatory response was a bar press and food was used as reinforcement during training. Although there were wide individual differences in rate of learning, all subjects learned to make both discriminations.
Journal of the experimental analysis of behavior, 1966 · doi:10.1901/jeab.1966.9-677