Human ethanol self-administration. I: The interaction between response requirement and ethanol dose.

The effects of work requirement on human ethanol self-administration were systematically examined. Healthy volunteers with a history of moderate alcohol consumption (12 to 16 drinks per week) were recruited as subjects. Four subjects self-administered 4, 8 or 16% w/v ethanol solution contingent upon completion of a fixed-ratio (FR) response requirement. The ratio requirements were FR 32, FR 64 and FR 128 responses. Ethanol consumption at lower doses decreased with increases in FR. Ethanol consumption at the high dose was greatest across all ratio requirements and was unchanged by increases in the ratio requirement, indicating greater relative reinforcing effects of the high dose of ethanol. Ethanol consumption was sensitive to unit price with 53-82% of the variance explained by the unit price analysis.