Effects of Frustration Increase and Decrease on Percentage of Short Interresponse Times

The finding by H. L. Armus (1986) that short (less than 1 s) interresponse times (IRTs) occur with greater frequency at higher levels of required lever-pressing effort was investigated. It has been hypothesized that greater percentages of short IRTs at higher effort requirements are an expression of frustration (S. Boyer & R. Carroll, 1980); in the present study, between-groups manipulations of effort and reward combinations were made in an attempt to increase and decrease relative frustration and thereby increase and decrease percentages of short IRTs. The subjects were 17 experimentally naive, male Long-Evans rats. Manipulation of effort requirements and reward magnitudes yielded both an increase and a decrease in percentage of short IRTs. The rats switched from low effort and high reward to high effort and low reward demonstrated the greatest increase in percentage of short IRTs, whereas the rats switched from low effort and low reward to high effort and high reward demonstrated a decrease in short IRTs.