Effects of a variable-ratio conditioning history on sensitivity to fixed-interval contingencies in rats.
Reinforcement history matters: prior VR training raises rats’ FI response rates yet still fails to mimic human FI patterns, so rat models have limits.
01Research in Context
What this study did
The team first trained rats on a variable-ratio schedule. After that, they switched the same rats to a fixed-interval schedule. They wanted to see if the earlier VR training would make the rats act like humans on FI.
Humans often keep a steady pace on FI instead of showing the usual scallop. The researchers asked whether a VR history would create that same steady pace in rats.
What they found
The VR history did raise the rats’ overall response rates on FI. Still, the animals did not copy the human pattern of steady, undifferentiated responding. They kept some rat-typical timing even with the higher rates.
How this fits with other research
Pisacreta (1982) and Poppen (1972) showed that human FI performance can lock into persistent pause or constant-rate styles. The 1995 rat study tried to recreate those human styles by giving rats VR experience first. It did not fully work.
Alba et al. (1972) found that rats only show FI-like patterns in avoidance when a signal marks the reinforcer. Together, these papers say that extra cues or histories shape FI responding in both species, but rats still respond like rats.
Wearden et al. (1983) noted weak autocorrelation in FI pauses. Adding VR history boosts rate, yet the basic pause-and-run structure stays, matching their view that pause length is hard to change.
Why it matters
If you hope to model human schedule control with animal work, remember that history helps but does not erase species differences. For clinical practice, watch for similar limits in your clients: past reinforcement can raise activity levels without changing the deeper timing pattern. Track both rate and shape when you assess skill or stereotypy.
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02At a glance
03Original abstract
We investigated the possibility that human-like fixed-interval performances would appear in rats given a variable-ratio history (Wanchisen, Tatham, & Mooney, 1989). Nine rats were trained under single or compound variable-ratio schedules and then under a fixed-interval 30-s schedule. The histories produced high fixed-interval rates that declined slowly over 90 sessions; differences as a function of the particular history were absent. Nine control animals given only fixed-interval training responded at lower levels initially, but rates increased with training. Despite differences in absolute rates, rates within the intervals and postreinforcement pauses indicated equivalent development of the accelerated response patterns suggestive of sensitivity to fixed-interval contingencies. The finding that the histories elevated rates without retarding development of differentiated patterns suggests that the effective response unit was a burst of several lever presses and that the fixed-interval contingencies acted on these units in the same way as for single responses. Regardless of history, the rats did not manifest the persistent, undifferentiated responding reported for humans under comparable schedules. We concluded that the shortcomings of animal models of human fixed-interval performances cannot be easily remedied by including a variable-ratio conditioning history within the model.
Journal of the experimental analysis of behavior, 1995 · doi:10.1901/jeab.1995.63-97