Behavior stability and individual differences in Pavlovian extended conditioning

TL;DR

This study extends associative models of Pavlovian conditioning to a dynamical oscillatory framework, revealing individual differences in behavior stability and demonstrating the extended model's superior fit to experimental data.

Contribution

It introduces a dynamical oscillatory model of Pavlovian conditioning with greater memory capacity and forecast uncertainty, explaining behavior stability and individual differences.

Findings

The extended model explains most data better than the Rescorla-Wagner model.

Behavioral oscillations were detected but with large dispersion.

Individual response fluctuations are characterized by white noise.

Abstract

How stable and general is behavior once maximum learning is reached? To answer this question and understand post-acquisition behavior and its related individual differences, we propose a psychological principle that naturally extends associative models of Pavlovian conditioning to a dynamical oscillatory model where subjects have a greater memory capacity than usually postulated, but with greater forecast uncertainty. This results in a greater resistance to learning in the first few sessions followed by an over-optimal response peak and a sequence of progressively damped response oscillations. We detected the first peak and trough of the new learning curve in our data, but their dispersion was too large to also check the presence of oscillations with smaller amplitude. We ran an unusually long experiment with 32 rats over 3960 trials, where we excluded habituation and other well-known phenomena as sources of variability in the subjects' performance. Using the data of this and another Pavlovian experiment by Harris et al. (2015), as an illustration of the principle we tested the theory against the basic associative single-cue Rescorla-Wagner (RW) model. We found evidence that the RW model is the best nonlinear regression to data only for a minority of the subjects, while its dynamical extension can explain the almost totality of data with strong to very strong evidence. Finally, an analysis of short-scale fluctuations of individual responses showed that they are described by random white noise, in contrast with the colored-noise findings in human performance.