“…In studies first reported by Boren, monkeys acquired a unique food-reinforced sequence of responses each day, thus allowing acquisition to be studied recurrently in a single organism The (Boren, 1963;Boren & Devine, 1968). Following these initial studies, the repeated acquisition baseline was adapted for assessment of drug-induced alterations in the acquisition of behavioral control in a number of species, including pigeons (e.g., Harting & McMillan, 1976;Thompson, 1976), rats (e.g., Calhoun & Jones, 1974;Handley & Calhoun, 1978;Pollard, McBennett, Rohrbach, & Howard, 1981;Schrot, Boren, & Moerschbaecher, 1976), dogs (Thomas & Schrot, unpublished, cited in Thompson & Moerschbaecher, 1979), the great apes (Pieper, 1976), and humans (Desjardins, Moerschbaecher, Thompson, & Thomas, 1982;Fischman, 1978). As pointed out by Thompson, the within-subject approach to the study of acquisition avoids many of the problems seen in group designs resulting from individual differences in the rate or speed of learning (Thompson, 1978, p. 190).…”