Experiment 4

Task:

Rats were given two signals one with high pay and the other with low pay. In the high pay condition rewards are always dropped while in low pay condition rewards are given in treatment probablities of 1 and then .25.

To prevent rats from tracking next oppurtinity for reward based on previous their previous response a bar press only had .25 probability of stopping the trial.

Figure 10

The data shows the effect perfectly.

The authors believe this shows that response variation is a function of reward anticipation. When the reward anticaption is low response variation, in this case button press duration, increases.

The authors then goes on to calucuate an extinction rate.

The analysis showed that as extinction increased, as measured by decreased bar press rate the response duration began to increase. This suggets that during extinction reward anticipation is reduced and therefore response variation increases.

Experiment 4 demonstrates that response variation occurs when reward anticpation is reduced. Furthermore it shows that when extinction occurs response vartiation goes up because reward anticipation decreases.