Nontemporal effect of ITI on discriminated one-way avoidance responding

Abstract

Three groups of hooded rats were exposed to a safe platform for different proportions of the ITI duration, in a signaled 1-way avoidance experiment. The rats with longer safe-platform exposure performed better than the ones with less exposure. These results are consistent with Denny's (1971) relaxation theory of avoidance learning.It is a well established finding that discriminated oneand two-way (directional) avoidance learning is an increasing function of duration of the intertrial interval (ITID), at least up to 5 min (BOice, 1970; Bolles & Grossen, 1970;Brush, 1962;Kurtz & Shafer, 1967;Levine & England, 1960). The functional relationship between directional avoidance learning and the ITID, moreover, seems to be much like that between a positively reinforced operant and its contingent reinforcer (Denny & Weisman, 1961). On the basis of the assumption that ITI's reinforce avoidance responding, the ITID may be said to be a measure of the reinforcement magnitude.There are also indications that ITIs can be functionally differentiated in terms of a nontemporal dimension. Specifically, given a constant ITID, the rate of directional avoidance learning seems to vary along the gradient of stimulus Similarity between the shock compartment and the compartment used to confine the subject during ITIs. Learning is markedly improved when the latter compartment is distinctively different from the shock compartment (Reynierse & Rizley, 1970), the rate of learning being directly related to the length 0 f confinement in the distinctive ITI com partment (potts & McKown, 1969;Tenen, 1966). In these latter experiments, for example, different groups of rats were trained to avoid a footshock by jumping onto a safe and distinctive platform. Subjects were gently pushed back onto the grid floor after they had spent prescribed durations on the platform. The results clearly indicated that subjects with longer platform exposure duration showed better learning.These findings, unfortunately, can at best provide an inconclusive support for the present view of nontemporal aspect of the ITI; in both these experiments, the effect of platform exposure time was invariably confounded with the facilitatory effect of the ITID in that a longer platform exposure resulted also in a longer ITID.The present study is an attempt to isolate the effect of a nontemporal aspect of ITI (Le ., platform exposure This paper is sponsored by Austin Riesen who takes full editorial responsibility for it. 55 during ITI) from that of its temporal aspect (Le., ITID), in a modified one-way apparatus. METHOD Subjects and ApparatusSubjects were 18 naive adult male hooded rats approximately 120 days of al(e. The apparatus consisted, basically, of a wooden box, 53 x 23 x 23 cm high (inside dimensions) with a Plexiglas top and a grid floor. At one end was located a horizontal platform made of Plexiglas, 1.27 cm above the grid floor. The platform formed a 23 x 23 cm surface at one end of the apparatus. The end walls consisted of two movable partitions which could be slid along...

Effects of duration of feedback on signaled avoidance

“…Weisman and Litner (1971) concluded that inhibition brought about by a stimulus is, in part, a function of the inhibition elicited by another stimulus present in the situation. Moreover, Cändido et al (1989), using a one-way response, found that the supposed reinforcing power of the time spent in the safety compartment depended on the time spent in the danger compartment (see also Denny, 1971;Modaresi, 1975Modaresi, , 1984. It may be that the reinforcing power of feedback does not depend on its absolute duration, but rather on its duration in relation to the danger-free period that follows-that is, the time without feedback before the start of the waming signal.…”

Successive Positive Contrast in One-Way Avoidance Learning

“…Several authors have also proposed that the perception of the causal relationships between the effective response and the absence of the shock and the danger signal in the safe compartment may confer incentive properties to the safe compartment or the safety signals associated with it. The safety signals might then activate a positive emotional system (relief) that acts as an incentive for the approach response to the safe compartment (Denny, 1971;Dickinson, 1980;Dickinson & Dearing, 1979;Gray, 1987;Masterson & Crawford, 1982;Modaresi, 1975;Mowrer, 1960;Toates, 1986).…”

“…Previous research has shown that in one-way avoidance learning, both acquisition and negative contrast were dependent on a "ratio" between the time spent in safety and the time in danger, but not on the total ITI (see Cándido et al, 1989, for a detailed discussion; Holloway & Baum, 1989;Modaresi, 1975). Experiment 2 aimed to examine whether the positive contrast effect also depended on the ratio between safe and danger time.…”

“…Usually, the larger the amount of reinforcement, the faster the learning (Mackintosh, 1974). In avoidance conditioning, different studies have also shown that a longer time spent in the safe compartment, where neither the warning signal nor the electric shock occurs, improves learning (Cándido, Catena, & Maldonado, 1984;Cándido et al, 1989;Denny, 1971;Modaresi, 1975). The similarity between these effects suggests that time spent in a safe place may act in a similar way to reward magnitude in appetitive paradigms (Dickinson, 1980;Gray, 1987;Mackintosh, 1983, for a review).…”