That an altered environment during development can effect altered behavior during adulthood has been reliably shown for a variety of experimental conditions and behavioral dimensions (Bovard, 1958;Hebb, 1958). In this study 5s were administered drugs which could alter the magnitude of the stimulus input and the nature of the internal milieu. On the assumption that the manipulations were consistent with the postulated mechanisms of early-experience effects (cf. Berlyne, 1960;Meier, 1960), the 5s' adult behaviors were examined for the changes seen in other earlyexperience studies in accord with the direction of the chemical change.
METHOD SubjectsSix litters of 3-day-old Long-Evans rats were each divided into three groups designated, according to drug administered: Ei (reserpine), Ez (deanol), and C (control: isotonic saline). At this time, the groups numbered 17, 16, and 16 5s, respectively; at the time of testing they numbered 13, 14, and 11 5s, respectively. The ratio of males to females was 7:6, 7:7, and 3:8.The rearing cages of all groups were the same: sheet metal, drawer-type cages fitted with wire mesh tops and measuring 14 in. by 16 in. by 7 in. deep. Standard laboratory, wire-mesh cages, 9 in. by 8 in. by 7 in. deep, were used after weaning at 24 days, when 5s were assigned 2 or 3 of like sex to a cage. These cages had sheet metal sides, backs, and tops with wire mesh fronts and bottoms.
ApparatusEmotionality. The apparatus for the measurement of emotionality consisted of a 30-in.-square field covered with gray oilcloth, with ruled lines marking off 6-in. squares. A 12-in.-high gray wall surrounded the field and two 100-w. incandescent bulbs illuminated it.Discrimination. The discrimination apparatus (Grice) has already been described (Meier & McGee, 1958). Briefly, it consisted of a start box and V-shaped discrimination chamber and three identical exposed goal boxes which could be shifted so that the discriminanda in the boxes appeared at the left or the right in a
