Experiment 1

Task:

In one trial a light goes and once 40 seconds has elapsed the next response drops a reward. The other trial type has the light turn on but no food is given during the duration.

Figure1

The data showed an increased rate that peaks at the end of the 40 second mark (Top). Further analysis was conducted on bar press duration which showed that this behavioral response was more erratic particularly at the 45 second mark (Bottom).

Figure 2

A further analysis revealed that bar press duration varied strongest in trials where food was omitted.

Conclusion:

What seemed to be happening here is that the rat would press the bar and while keeping the bar pressed would vary how long it would keep the bar pressed. To account for this the authors hypothesized the reward being omitted caused the frustration effect in the rat leading them to hold down the bar longer.