Ethanol consumption and the matching law: A choice analysis using a limited-access paradigm

Choice analyses, especially R. J. Herrnstein's (1961, 1970) matching law, have recently been extended to substance abuse and drug research. The experiment reported here used a limited-access paradigm to engender ethanol consumption in Sprague-Dawley rats (Rattus norvegicus). After stable ethanol consumption was established, several 2-bottle choice tests were run. Relative volumes of solutions consumed were compared to relative ethanol concentrations as an application of the matching law. The formula for the generalized matching law confirmed that although biases varied, they were small, and more important, sensitivities to the relative concentrations were positive in 24 of 28 subjects. The results also revealed a high positive correlation between baseline ethanol consumption (g/kg) and subsequently assessed sensitivity. Overall, these findings suggest that a matching law analysis can be useful for examining ethanol intake in randomly bred rats.