Factors affecting the acquisition and elimination of children's donating behavior

Thirty-five 6- to 10-year-old children with initial low rates of donating to help a peer either simply received a fine for each failure to donate (n = 7) or also were informed of the contingency between the fine and failure to donate (n = 28). Explanation of the contingency was necessary to increase children's donation rates. Donations continued at high rates during a gradual, unannounced removal of the fine contingency, but decreased when children were informed that fines were no longer in effect, particularly for children who had failed to donate at least once during training and had actually been fined. Overall, addition of a distraction or an inequity procedure did not reduce donating below rate reductions due to the announced extinction procedure alone.     

Second-order avoidance behavior in monkeys

Two monkeys were trained on a three-component multiple schedule using discrete trials. In one component (food), a response terminated a red stimulus and produced food and S(Delta). In the second component (avoidance), a response terminated a green stimulus and avoided shock. In the third component (optional), a response terminated a blue stimulus and produced S(Delta). The consequence of not responding in the blue stimulus, however, was the production of either a food or an avoidance trial. Manipulation of these consequences showed that when food trials were available only a small percent of the time after optional trials, the subjects tended not to respond in the blue, even though this led to an increase in the total number of avoidance trials per day. If only avoidance trials followed as a consequence of not responding in the optional component, the animals terminated the blue stimulus and avoided the avoidance trials. Throughout the experiment both subjects maintained consistently low shock rates (about 10 per day) and these were not affected by the various manipulations. The data suggest that a stimulus associated with avoidance can be a conditioned aversive stimulus and will maintain a more remote avoidance response under certain conditions.     

The elimination of interfering response patterns in lever-press avoidance situations

Lever holding into shock and short-latency responses to shock onset are two response patterns that interfere with avoidance acquisition in free-operant and discriminated avoidance situations. In an attempt to eliminate these patterns, an additional timer disabled the lever for a period slightly longer than shock duration. A free-operant avoidance schedule with a warning stimulus, but without the additional timer, constituted the control condition. The lever-disabling timer was turned on by different events in two experimental conditions: (a) release of the lever at the onset of shock, (b) shock onset. Interfering responses diminished most rapidly, and efficient avoidance behavior appeared earliest, when the lever-disabling timer was turned on by shock onset.     

Extinction of Sidman avoidance behavior

Extinction of Sidman avoidance behavior by eliminating the noxious stimulus was studied in Sprague-Dawley rats with bar-pressing as the response. Each of three subjects was trained and extinguished on each of the following schedules in a different order: nondiscriminated, response-shock interval = 20 sec, shock-shock interval = 5 sec; nondiscriminated, response-shock interval = 40 sec, shock-shock interval = 5 sec; discriminated, response-white noise interval = 15 sec, noise-shock interval = 5 sec, shock-shock interval = 5 sec. Less than one 4-hr session was required for extinction for all procedures. When a warning stimulus was present, resistance to extinction increased. Subjects did not, however, respond to avoid the signal. Only small differences in extinction were found after training on different schedules with no warning signal.     

Stimulus control of avoidance behavior

The introduction of a warning signal preceding shocks greatly increased the effectiveness of avoidance responding. Periods of “warm-up” at the beginning of the session were eliminated, and the number of shocks received by the subjects was greatly reduced. With response-shock interval constant, response rate increased as the interval between the response and the onset of the warning signal was shortened. The response tended to occur shortly after the onset of the warning signal regardless of the duration of these “safe” periods. A greatly elevated response rate was maintained even when the duration of the safe period was reduced to 0.3 sec. Thus, the pre-shock signal obtained nearly exclusive control of the responding and overrode the usual “temporal discrimination” of the response-shock interval.     

Signal functions in discriminated avoidance behavior

Four rats were trained to lever press under a discriminated avoidance/escape schedule in which separately signalled safe and warning periods were 100 sec and 32 sec respectively. The auditory and not the visual component of the compound warning signal became associated with the discriminative control of lever pressing. Avoidance behavior also came under temporal control, in that the probability of lever pressing increased as the warning period progressed. Timing began with the onset of the warning signal rather than the offset of the safe signal. However, after the warning signal had been progressively eliminated, timing began with the offset of the safe signal. When neither signal was normally available, the temporal distribution of avoidance behavior changed markedly. Drifts in the temporal distribution of lever pressing occurred throughout the study; these were manipulated for two animals.     

Shaping avoidance behavior in restrained monkeys

Lever-pulling avoidance behavior of 24 monkeys was actively shaped with a manual shock-control box and a closed-circuit TV system. A negative reinforcement procedure was used wherein a periodically occurring body shock was postponed each time the subject moved toward the lever. All subjects were trainable with this method, two-thirds of them in fewer than five, 1- to 2-hr sessions. Negative reinforcement was more effective than a punishment procedure.     

On the role of US expectancies in avoidance behavior

In studies on avoidance learning, a warning signal is followed by an aversive outcome (US) unless the participant makes a particular response. Several theories have been developed to try to explain the mechanisms underlying avoidance learning. Surprisingly, stimulus-response (S-R) theories and cognitive theories of avoidance learning have rarely been compared experimentally. These theories differ in the role they assign to the US representation in avoidance learning. We used a method often used to investigate the contribution of the US representation-namely, US revaluation. Participants first learned to avoid two different negative USs. In a revaluation phase, the value of one US became positive, whereas the value of the other US remained the same. The results indicated that after the revaluation phase, participants avoided the positive US less than the negative US. These results cannot be explained by S-R theories of avoidance learning.     

Effectiveness of the counterconditioning procedure in eliminating avoidance behavior

Data were obtained on the effectiveness of three forms of counterconditioning—each differing in the degree to which competing responses were introduced. Counterconditioning was also compared with an extinction procedure in eliminating an instrumental avoidance response. Only the counterconditioning procedure which evoked and reinforced another conditioned response during extinction of the avoidance response, was significantly more effective than a traditional extinction procedure in achieving a decrement in avoidance responding and this was only on the first session on which such procedures were in effect. When the opportunity to perform the competing response was removed, only Ss in this group evidenced a significant increase in avoidance responding.

All procedures were equally effective over sessions in eliminating avoidance behavior. A delay in effectiveness occurred to the degree to which a procedure introduced a competing response. It was in terms of the immediacy of response reduction and achievement of a very low rate of responding with very few responses being performed, that the counterconditioning procedure was superior to the extinction procedure.

The implication of these results for behavior theory and therapy were elaborated.     

Generalization of free-operant avoidance behavior in pigeons

Three groups of four pigeons, trained to press a treadle on a free-operant avoidance schedule, were given auditory discrimination training. Alternating 2-min components of avoidance and no shock were paired with either a tone or white noise. The pigeons were subsequently given two types of generalization tests, with and without avoidable shocks scheduled. Two of the groups, trained interdimensionally, produced excitatory and inhibitory generalization gradients along the tone frequency dimension. A predicted post-discrimination gradient was computed from the algebraic summation of these gradients of excitation and inhibition. The predicted gradient was compared with the actual post-discrimination gradient obtained from the third group of pigeons that had been given intradimensional discrimination training on the tone frequency dimension. The predicted postdiscrimination gradient agreed in shape with the empirical postdiscrimination gradient. The results in general support Spence's (1937) gradient interaction theory.