Preexposure to situational cues produces a direct relationship between two-way avoidance learning and shock intensity

Abstract

In Experiment I, four groups of subjects (n = 16 each) were exposed to the situational stimuli of a shuttlebox apparatus for 4 h. Subsequently, 200 two-way avoidance trials were administered (100/day) with either .3-or 1.6-mA shock and with either small or large reward (presence or absence of visual stimuli following the response). Avoidance performance was directly related to shock intensity on both days and to magnitude of reward on the 2nd day. In Experiment 2, four groups of subjects (n = 24 each) were given 4 h of exposure either to the situational stimuli of the shuttlebox or to a neutral box. Then, 10 two-way avoidance trials were given with 1.6-mA shock. Subsequently, subjects were allowed to escape from one of the shuttlebox compartments to an adjacent safe box. Following preexposure to situational stimuli, avoidance performance was superior whereas escape-from-fear performance was inferior. This latter finding demonstrated that less fear of situational cues was present during avoidance training in the preexposed condition. All of these results support the effective reinforcement theory, an extension of two-factor theory, which emphasizes the importance for avoidance learning of the amount of fear of situational cues present following a response. 165In a one-way task in which subjects can avoid shock by moving to an area distinctively different from the one where shock is administered, avoidance performance has been found to be directly related to shock intensity (Dieter, 1976;Moyer & Korn, 1966). However, when an avoidance response does not remove the subject from situational stimuli which have been paired with shock, as in signaled two-way or barpress avoidance tasks, performance has been found to be related inversely to shock intensity, at least within the range of intensities usually employed. This latter finding is, in fact, one of the most reliable in the avoidance learning literature (e. A theoretical position which seems to account for the above findings is the effective reinforcement theory proposed by McAllister et al. (1971McAllister et al. ( , 1976 as an extension of the two-factor theory of avoidance learning (Mowrer, 1947). According to this position, the effective reinforcement for an avoidance response is related (a) positively to the amount of fear reduction occurring with the response and (b) negatively to the amount of fear present following the response. In addition, as the total amount of fear increases, it is assumed that the amount of fear present following the response (b) becomes relatively more important than the amount of fear reduction (a) in determining effective reinforcement. In the signaled twoway avoidance task, fear becomes conditioned to both the discrete conditioned stimulus (CS) and to the situational cues of each shuttle compartment when shock occurs on escape trials, with more fear being conditioned to these stimuli the more intense the shock. Although the amount of fear reduction would be greater in a strong-than in a weak-shock group when the CS is terminated fo...

Fear of the CS and of the context in two-way avoidance learning: Between- and within-subjects manipulations

“…With context fear reduced in this manner, performance was enhanced such that the typical inverse relationship between shock intensity and two-way avoidance performance was eliminated. W. R. McAllister et al (1979) extended these findings by demonstrating not only that the inverse relationship was eliminated by attenuation of context fear with a preexposure treatment, but also that when training was extended, a direct relationship between shock intensity and avoidance performance was obtained. Finally, there are numerous examples of improvement in two-way avoidance performance resulting from a reduction in the amount of contextualcues fear present after the instrumental avoidance response.…”

“…A direct relationship between shock intensity and twoway avoidance performance was also reported by W. R. McAllister et al (1979). These investigators administered nonreinforced preexposure to the contextual cues prior to avoidance training with either strong or weak shock.…”

“…can, however, account for the inverse relationship and can also predict how certain variables can alter this relationship. Their effective reinforcement theory (see also W. R. McAllister, D. E. McAllister, Dieter, & James, 1979) is an elaboration of Mowrer's (1947) two-factor theory of avoidance learning. The important role played by fear of the conditioned stimulus (CS) in accounting for two-way avoidance learning is acknowledged, but in addition, the contribution of the fear conditioned to the contextual cues is emphasized.…”

Bidirectional avoidance by mice as a function of CS, US, and apparatus variables

“…Shock intensity and other related effects have generally been explained either by response competition models (Moyer & Korn, 1964;Theios et al, 1966) or by reinforcement models (Dieter, 1977;McAllister et al, 1971;McAllister, McAllister, Dieter, & James, 1979). However, the controversy on this point does not need to be considered for the purposes of the present work.…”

“…In addition, all mice trained with 1.5-rnA shock initially showed many signs of distress, such as loud squealing, wild running, andjumping. At a comparable punishmentlevel, all experiments with rats haveshown a depression of bidirectional avoidance, except in the case of manipulations aimed specifically at a reduction of fearconditioning to general apparatus cues (see particularly Dieter, 1977, andMcAllister et al, 1979). In this way, bidirectional noise-eued avoidance in mice resembles one-way, rather than two-way, avoidance in rats, reminiscent of the modified bidirectional tasksin whichthe adverseinfluence of a high shock intensity is eliminated (Modaresi, 1975).…”