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Operant conditioning techniques were applied to the study of how target fixations are controlled by the probability of signal occurrence. In a standard vigilance setting, gaze at three illuminable volt meters was monitored by a Mackworth television eye camera with automatic recording capability. Gaze at a given meter produced illumination of the meter, and signals (deflections of the needle on the meter) were scheduled as intermittent consequences of this response. Target fixations were thus placed under the control of concurrent variable‐ratio, differential‐reinforcement‐of‐low‐rate, and fixed‐interval schedules in normal adult volunteers.

Three rats were trained on a schedule in which a response on lever B was reinforced only if it was preceded by a minimum number of consecutive responses on lever A. The minimum requirement was 27 A responses for Rat 1, and 20 A responses for Rats 2 and 3. The schedule maintained high rates of responding on lever A, and a slow, spaced pattern of responding on lever B. The mean number of consecutive responses on lever A was slightly greater than the minimum required. The effect of superimposing on this behavior a stimulus that ended with an unavoidable shock was the suppression of responding on both levers during the pre‐shock stimulus. Responses on lever A were more suppressed, and the proportion of relatively short response runs on lever A during the pre‐shock stimulus increased. With all three rats, the mean number of consecutive responses on lever A during the pre‐shock stimulus decreased to a value below the minimum requirement for reinforcement of the subsequent B response.

An operant conditioning approach was successful in getting a chronic psychotic patient to give factual answers to direct questions that had previously elicited only delusional responses. Multiple baseline and reversal controls established that the changes were due to the experimental procedure. The subject was a female patient classified as paranoid schizophrenic who had persisted in giving bizarre responses to direct questions regarding her identity, age, and personal history during 26 yr of hospitalization. She was discharged after factual answers to these questions had been obtained, but operant conditioning trials were continued in the community to promote generalization. Two follow‐up interviews were conducted 36 and 52 days after discharge to evaluate generalization. No generalization was found in the first interview, but the second gave evidence of some generalization.

Bees learned to enter a Plexiglas tube and to suck small portions of sugar solution; every entry or every fifth entry was reinforced. During an extinction phase, the bees on the fixed‐ratio schedule emitted twice as many responses as did those given continuous reinforcement. Bees on a fixed‐interval schedule of reinforcement emitted lower response rates than did those given fixed‐ratio reinforcement. By extending the conditioning procedure for several days, it was possible to maintain responding with fixed‐ratio schedules requiring 30 responses per reinforcement and with fixed‐interval values up to 90 sec. Under fixed‐interval schedules, response rates did not increase toward the end of the reinforcement intervals.

In Experiment I, pigeons were given equal reinforcement (variable‐interval 1‐min) for responding during randomized presentations of eight line‐orientation stimuli. Then, only responding in the vertical orientation was reinforced. Stable generalization gradients soon formed and persistent behavioral and local (transient) contrast effects appeared. Local contrast effects were not a function of relative reinforcement frequency or of any other variable known to produce contrast. Instead, they were related to average response rates associated with each stimulus. Experiment II showed that local contrast effects represent increases and decreases in response rates relative to baseline responding, and that these effects are relative; a given stimulus might enhance responding during a subsequent presentation of one stimulus, but depress responding when followed by another. These data indicate that discrimination learning is not adequately described as the acquisition of excitatory properties by some stimuli and inhibitory properties by others. A more adequate account implies that stimuli exert both excitatory and inhibitory effects related to their value.

A classroom teacher modified the behavior of a 10‐yr‐old student who had a high rate of obscene vocalizations accompanied by facial twitches. In the first phase, the subject was instructed to repeat rapidly the most frequent obscene word in four daily 15‐min sessions. This procedure reduced the frequency of obscene vocalizations, but not to an acceptable level. Subsequently, the teacher was able effectively to control the target behavior using a timeout procedure.

Auto‐shaping the pigeon's key‐peck response was examined as a respondent conditioning procedure with the use of Rescorla's truly‐random control procedure. In the first experiment, pigeons received presentations of brief light on the response key and brief presentations of food where the light and the food were independently presented. All birds failed to key peck after many light and food presentations, but explicit pairing of the light and food rapidly conditioned pecking to the light. Experiment 2 showed that even when an independent light/food presentation schedule was reduced to variable‐time 30 sec, additional naive birds would not key peck and only one bird pecked when the schedules were variable‐time 15 sec. A third experiment examined an explicit‐unpairing control procedure, where the light and food were not only presented on independent schedules but were also separated by a minimum time, and found that auto‐shaping did not occur. A fourth experiment investigated a number of control procedures and found them ineffective. A fifth experiment investigated the effects of a physical separation of the locus of the response key and the food dispenser, and a sixth experiment investigated using a tone in place of the light. It was concluded that pecking is generated by auto‐shaping procedures only when an intermittently presented keylight is regularly paired with food.

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