Cyclophosphamide-induced aversions to saccharin-flavored tap water were observed in normal control rats, in rats subjected to varying numbers of cyclophosphamide injections prior to conditioning, and in rats similarly subjected to preconditioning saline injections. Both initial magnitude and resistance to extinction of a conditioned flavor aversion were found to be inverse functions of preconditioning familiarity with drug-induced illness. Six preconditioning cyclophosphamide injections markedly reduced both initial aversion magnitude and resistance to extinction. In contrast, three such injections fail ed to affect initial aversion magnitude and resulted in a small acceleration of extinction rate, while one preconditioning cyclophosphamide injection produced no observable effects. These findings depict preconditioning familiarity with illness as one important variable modulating the strength of conditioned flavor aversions and emphasize the importance of viewing resistance to extinction as one indicator of aversion strength.Bait-shyness, the learned avoid ance of a substance whose consum ption is followed by a case of nonlethal poisoning, is conveniently studied in laboratory rats by following the ingestion of a palat abl e flavor with illness induced by to xic injection or ex posure to ionizing radiation (cf, Garcia & Koelling , 1967 ; Revusky & Gar cia, 1970). Flavor familiarity prior to condit ioning is one important variable influencing the strength of these conditioned aversions. Numerous studies have shown th at preconditioning flavo r fam iliarity reduces th e strength of both radiati on and drug -induced flavor aversions (Ahlers & Best , 1971 ;Domjan , 1972 ;Elkins, 1973a; Farley, McLaurin , Scarborough, & Rawlings , 1964; Revu sky & Bedarf, 1967;Vogel & Clody, 1972; Wittlin & Brookshire, 1968). A related problem , which has received less attention , involves famili arity with illness prior to conditioning. Brookshire and Brackbill (1971) reported that 10 pre conditioning injections of apomorphine hydrochloride blocked the development of an apomorphine-induced flavor aversion . Apomorphine hydrochloride induces nausea and vomiting in humans and has been used in aversion therapy for alcoholism. However, Lemere and Voegtlin (1950), who t reated over 4,000 alcoholics with " conditioned reflex therapy," a procedure based on repeated pairings of alcohol ingestion with chemically induced illness , advised against apomorphine as a conditioning agent because their results suggested its effectiveness was to som e extent negated by its sedative action. Similarly, the aversion attenuation reported by Brookshire and Brackbill (1971 ) might be, in part , a funct ion of narc otic effects as *A preliminary revision of this paper was presented at the 1972 meeting of the Southwestern Psychological Association, Oklahoma City.
MeadJohnson Laboratories) is, th erefore, indicated. Since functional relationships between bait-shyness and differing amounts of preconditioning toxic illnesses are unknown, this experiment al...
