Fixed-Ratio and Time-Out Changes on Behavior Maintained by Cocaine or Methohexital in Rhesus Monkeys: 2. Behavioral Economic Analysis

Data from Winger (1993) in which the ability of cocaine or methohexital to maintain responding on schedules in which either fixed-ratio (FR) or time-out (TO) values were varied were analyzed with a behavioral economic approach. For methohexital, a single function described the relation between price (FR value divided by dose in mg/kg/injection) and consumption (mg/kg/session). For cocaine, however, drug consumption at prices determined by larger ratios and doses was greater than consumption when these prices resulted from smaller ratios and doses. Under conditions of changing TO values (changes in income), the predicted parallel shifts in the demand curves for cocaine were observed, but the shifts in methohexital demand curves were not parallel. These data indicate that a unit price analysis might account adequately for some aspects of drug-maintained behaviors while adding little descriptive power to others.