Malath Makhay

Date of Award


Degree Name

Master of Arts



First Advisor

Dr. Alan D. Poling

Second Advisor

Dr. Lisa Baker

Third Advisor

Dr. Anna Kay Campbell

Access Setting

Masters Thesis-Open Access


The effects of acute cocaine administrations (5. 6 to 32 mg/kg) were determined in rats responding under a multiple fixed-ratio 15 fixed-ratio 15 schedule of food delivery. The minimum response effort required in one schedule component was 25 g, whereas in the other component it was 200 g. Cocaine produced generally dose-dependent decreases in rate of responding and increases in pre-ratio pause times under each component. There was, however, a significant interaction between force and drug dose, and the magnitude of drug effects were larger in the component requiring 200 g for lever operation. Although a number of other parameters have been shown previously to modulate the effects of cocaine on schedule-controlled responding, the present data constitute the first demonstration that minimum response effort does so.