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Pigeons were trained to respond on a multiple variable‐interval 1‐min variable‐interval 1‐min schedule, then switched to a multiple variable‐interval 1‐min differential‐reinforcement‐of‐other‐behavior discrimination training. The rate of reinforcement was held constant during the shift from non‐differential reinforcement to discrimination training. Behavioral contrast and post‐discrimination inhibitory stimulus control followed the observation of a reduction in the rate of responding to the stimulus correlated with reinforcement for the non‐occurrence of pecking.

After varying lengths of baseline, initiation of a feedback system increased the daily use of operant training methods by non‐professional hall personnel in a state institution for retarded children.

Pigeons were exposed to three stimuli simultaneously, with responses to one of them, the positive stimulus, followed by food presented according to a fixed‐interval schedule (FI 2‐min, FI 4‐min, FI 8‐min, or FI 16‐min). Over 90% of the total responses emitted were to the positive stimulus within a few sessions. When the birds were then studied under each of four fixed intervals, responding continued to be confined primarily to the same stimulus independent of interval size. In subsequent conditions, the three stimuli changed positions after each quarter of the interval. If the position changes did not require a response, response rate and the percentage of responses occurring to the positive stimulus decreased. If the changes did depend on a response, the complete interval appeared to be divided into four smaller intervals with a pause and then positively accelerated responding following each position change. Position changes produced by a response to any stimulus decreased control by the positive stimulus, and changes produced only by a response to it increased the percentage of responses made to that stimulus. All of the data suggested that the stimulus conditions contiguous with reinforcement controlled behavior.

Several experiments have found complete retention of conditioned suppression when overall suppression to the signal for shock was measured. The present experiment examined retention of conditioned suppression but did so with a paradigm that produced temporal discrimination of shock occurrence. Nine rats were exposed to a flashing light signal of 5‐min duration that always terminated with a shock. After several months, a temporal discrimination was well established, as shown by maximum suppression toward the end of the signal period. After remaining in the home cage for 25 days, the rats were again subjected to the conditioning procedure. The overall level of suppression remained the same but the temporal discrimination was not observed.

Key‐peck responses of pigeons under a fixed‐rate 60 (Exp. I) or fixed‐ratio 99 (Exp. II) schedule of positive reinforcement were punished by response‐dependent electric shock during a segment of the ratio. The punishing stimulus was scheduled in one of three locations: the first third of the ratio, the middle third, or the final third. At high shock levels, the different loci of punishment differentially affected the typical fixed‐ratio performance pattern. Post‐reinforcement pauses were lengthened by all punishment conditions but to a greater degree when the responses in initial third of the ratio were punished. Disruption of responses before the punished segment of the ratio was a conspicuous feature of the performances when the middle or final third of the ratio was punished. Two of the punishment conditions produced similar effects on both fixed‐ratio baselines but punishing the final third of the ratio suppressed the punished responses of the ratio only with the fixed‐ratio 99 schedule. General effects of all punishment conditions included consistent intrasession recoveries of partially suppressed performances, the rapid recovery of the FR performances after the punishment dependency was removed after complete suppression, and the facilitation of overall and/or local response rates of most subjects by low‐intensity shock.

A free‐operant avoidance schedule was used to establish and maintain foot‐treadle responding by two Homing, one White King, and two Carneaux pigeons. In the absence of responding, the interval between shocks equaled 10 sec. Each time a treadle response occurred the shock was postponed for 32 sec. Pigeons appear to learn the treadle response more quickly and use it to avoid shock more successfully than do rats bar pressing on similar schedules. The treadle response becomes highly stereotyped and interresponse time distributions obtained from terminal behavior appear very similar to data obtained from rats. It is concluded that the difficulty in training pigeons to avoid electric shock is not in establishing avoidance behavior but in attempting to evaluate such behavior with the key‐peck response.

Fifteen pigeons were given conditional discrimination training in which a colored sample stimulus determined which of two line comparison stimuli (vertical and horizontal) was correct. As part of the conditional discrimination procedure, birds were required to make an “observing response” to the sample stimulus presented on a wide key. The location on this key of the required observing response for the two sample stimuli differed by 0, 3, or 6 in. (0, 7.6, or 15.2 cm) for three groups of birds. Accuracy of conditional discrimination performance was directly related to the amount of separation. In subsequent generalization tests with novel sample stimuli, both observing‐response location and comparison responding changed within the same region of the wavelength continuum from that appropriate for one of the training samples to that appropriate for the other. A maintained generalization test (continued reinforcement for training stimuli) revealed this relation more strongly. A test in which observing‐response location was the only sample stimulùs of a conditional discrimination revealed stimulus control by this observing response, supporting a response mediation interpretation of the data.