The effect of intersession interval in shuttle- box conditioning of the guinea-pig

Abstract

·AbstractSixty guinea-pigs were given 50 avoidance conditioning trials in a shuttle-box and then retested either 0, I, 24, 48, of 168 hr. later. Little improvement in performance was observed within sessions but animals retested at 48-and 168-hr. intersession intervals were substantially better than all others. ProblemIn a study of shuttle-box avoidance conditioning in guinea-pigs, the authors found that animals made few avoidance responses in 50 or even 150 trials and showed little or no improvement in performance over trials. If the Ss were given a second training session two days later, a striking improvement was noted. One S made only three avoidance responses in the first session of 50 trials (only 1 in the last 20 trials) but made 18 avoidance responses in a 20 trial session two days later. The present study was conducted to confirm these observations and to explore the improvement in performance as a function ofthe duration ofthe intersession interval. MetbodThe Ss were 60 experimentally naive, young, female gUinea-pigs ranging in weight from 320 gm to 515 gm at the start of the experiment. The apparatus was a two compartment shuttle-box 30 in long, 6 in high and 7 in wida. There was no partition between the two halves of the box. The top and front side of the box were made of Plexiglas, the back and ends were unpainted plywood. The floor of each compartment consisted of 30 metal rods set 1/2 in apart. The CS was from a Holtzer Cabot 24-v buzzer suspended 9 1/2 in above the center of the box and from one of two 25-w lights mounted 2 1/2 in above the Plexiglas top at the ends of the box. The light over the compartment occupied by S was made to flash at 1 cycle per sec. A scrambled shock source (GrasonStadler, Model E6070B) supplied 3 ma at 350 v, 60 cycles, A. C.The first training session was the same for all Ss. After a 5-min. habituation period in the apparatus, each S was presented with the CS alone until no reaction was made for three consecutive trials. After the Ss had become acclimatized to the CS, 50 delay conditioning trials with a 10-sec. CS-UCS interval and I-min. intertrial interval were given. Both CS and UCS were terminated when the S crossed the center line of the shuttle-box.The 60 Ss were randomly assigned to five experimental groups with 12 Ss in each group. Each group received a second training session of 25 trials after an interval of 0, I, 24, 48, or 168 hr. With the exception Ptychon., Sci., 1964, Jlol. 1. C. D. Webster and Ronald G. RabedeauQUEEN'S UN~IT~ CANADA of the 0 interval group, Ss were returned to their living cages for the appropriate interval between sessions. In order to equate handling, Ss in the 0 interval group were taken from the apparatus after the 50 trials of the first session and replaced 30 sec. later. ResultsThe results in terms of percentage avoidance responses in blocks of trials are shown in Fig. 1. Since an analysis of variance on total number of avoidance responses for different groups in the first session was not significant, the individual group curves ha...

The effects of bilateral hippocampal lesions on two-way active avoidance in the guinea pig

“…These earlier works and the present study c1early demonstrate a facilitatory effect of large bilateral hippocarnpallesions on the performance of a two-way shuttle-box problem. The appearance of this phenomenon in the present study is particularly impressive, considering the normally poor performance displayed by guinea pigs on tasks of this nature (Evoni~ ~ Brimner, 1967;Webster & Rabedau, 1964;Webster et al, 1965). It may be that this is a general phenomenon in rodents, even those ordinarily unable to learn such tasks.…”

“…Training sessions were spaeed 24 h apart. This particular training procedure was expected to produce very little learning of the avoidance response in normal Ss (Evonic & Brimer, 1967;Webster & Rabedau, 1964;Webster, Brimer, & Evonic, 1965). An Esterline Angus event recorder was used to record avoidance responses, spontaneous crossing, and response latency.…”

Shock intensity effects in shuttle-box conditioning of guinea pigs

“…In addition to differences in initial performance, the present study also demonstrated the sharp increase in avoidance level following a 48-h rest as originally reported by Webster & Rabedeau (1964). Of interest here is the fact that the intersession improvement was greater for the first-session low and medium groups than for the first-session high group and that it was independent of second-session shock intensity_ Thus, the factor that interferes with performance does not disappear after 48 h if the initial training is conducted with very high shock.…”

The inverse relationship between shock intensity and shuttle-box avoidance learning in rats: A reinforcement explanation.

“…Another way by which effective reinforcement may be increased is to provide a 48-hr, interval between shuttle-box sessions since fear of apparatus cues, but not fear of the discrete CS, shows forgetting in this length of time following conditioning (Goldman, 1969;McAllister & McAllister, 1968). Data reported by Webster and Rabedeau (1964) and by Rabedeau and Webster (1970), which show an improvement in shuttle-box avoidance learning in guinea pigs after a 48-hr, intersession interval, are consistent with this interpretation. In the latter study it was reported that the improvement in performance was greater in low-and medium-than in high-shock groups.…”