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Two retarded children were taught to name pictures according to a standardized procedure. In Exp. I, correct responses were positively reinforced on a five to one ratio under one stimulus condition, incorrect responses were followed with a sharp “no”, and the subject was ignored for inattentive behavior. Under another stimulus condition, correct responses were reinforced as in the first condition, but incorrect responses and 5‐sec periods of inattentive behavior were followed by “no” and an electric shock. Less inattentive behavior was exhibited and more words were learned to a pre‐set criterion in the shock condition than in the no‐shock condition. In Exp. II, the ratio of inappropriate responses to shock was varied. The amount of inattentive behavior tended to increase in the shock condition, relative to that in the no‐shock condition, as this ratio was increased. Two other measures of performance used in the present experiments were the ratio of errors to correct responses and the number of correct responses. Shock tended to produce better performance on these measures also.

Shock‐induced biting and threat by the male painted turtle (Chrysemys picta marginata) were studied in three experiments. When restrained facing each other, the turtles threatened and bit other turtles in response to electric shock. Shock alone caused turtles to threaten an unshocked turtle; the movements of a shocked turtle were sufficient to cause an unshocked but restrained turtle to threaten. When the turtles were free to move, they avoided an encounter when shocked, even reversing a strong position preference in order to do so.

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.

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Three pigeons received visual discrimination training under both multiple variable‐ratio extinction and variable‐interval extinction schedules. All birds developed nearly perfect discrimination. When punishment for every tenth response during food reinforcement was presented, responding decreased as shock intensity increased. At the same time, responding during extinction, which was not punished, increased at intermediate punishment intensities, but returned to low levels under severe punishment. A second procedure, in which punishment and no‐punishment sessions alternated unsystematically, was employed with two of the birds. The results under this procedure essentially replicated the data obtained as punishment shock intensity increased gradually.

In Exp. I, rats' lever presses were conditioned on multiple variable‐interval variable‐interval schedules. Changing one of the multiple schedule components to variable time reduced responding in that component. Further reductions in responding occurred in both components when the schedule was changed to multiple variable‐time variable‐time. After reinstating the multiple variable‐interval variable‐time schedule, lower response rates were maintained in the variable‐time component during a series of stimulus reversals. In Exp. II, replacement of extinction components of multiple variable‐interval extinction or multiple extinction extinction with variable‐time schedules for single sessions (probe) resulted in response rate increments in those components. In the former schedule these increases were concomitant with response decreases during the variable‐interval components. Response increases in the variable‐time probes were related to conditioning history and, as a result, to response probability at the time of the probe.

In each baseline session, pigeons were exposed to a multiple schedule in which each of five distinctive stimuli was correlated with a different frequency of reinforcement. In one component, responses were reinforced with a probability of 0.10 (random‐ratio schedule); in the other four components, responses were reinforced with different scheduled temporal frequencies averaging 30 to 240 sec between reinforcements (random‐interval schedules). For periods lasting 30 sessions, contingent reinforcement was discontinued and reinforcement was presented independent of responding at irregular intervals averaging 30, 60, or 120 sec, while the sequence of stimuli continued. After each such period, the baseline was reinstated for 30 sessions. The data indicated that: (1) The rate of responding in the presence of all stimuli decreased as exposure to the non‐contingent reinforcement procedure was prolonged, at all the frequencies of reinforcement employed; (2) The rate under the random‐ratio schedule declined faster than the rates under all the random‐interval schedules, presumably because the decrease in reinforcement frequency under this stimulus condition was greatest; (3) The decline in rates of responding under the stimuli correlated with the random‐interval schedules tended to be greatest for the stimuli paired with the lowest frequencies of reinforcement.

Responding in three food‐deprived rats was reinforced on schedules in which reinforcement periods (fixed‐ratio 1 or 2 for 1, 3, 6, 9, 14, or 21 reinforcers) alternated with extinction intervals. Schedule‐induced drinking occurred and was mostly confined to the onset of extinction intervals. Drink durations were longer after 21‐pellet meals but were not reliably different after 1, 3, 6, or 9‐pellet meals. When termination of the extinction intervals was response dependent, schedule‐induced drinking diminished until minimum extinction intervals of 15, 30, and 60 sec were introduced.

Pigeons were used to assess stimulus control during the development of a conditional discrimination. The training consisted of three stages. In Stage 1, key pecks were reinforced in the presence of a white line tilted 40° to the right of vertical on a green background and non‐reinforced when the same line appeared on a red background. In Stage 2, key pecks were reinforced when a white vertical line appeared on a red background and were non‐reinforced in the presence of a 40° slanted line on a red background. In Stage 3, key pecks were reinforced in the presence of the green background regardless of the line tilt, but were differentially reinforced in the presence of the red background (as in Stage 2). Generalization tests were conducted after each stage of training and consisted of five white lines on backgrounds that were green, red, or dark. The effects of the differential reinforcement contingencies on control by line orientation were restricted to the condition in which the red light appeared and resulted in behavioral control that could be characterized as: if red, pay closer attention to line tilt than if not red.

The effects of discrimination and avoidance training on the skin resistance response were studied in eight humans. Responses occurring during one stimulus delayed the interruption of music for 30 sec; responses during a second stimulus either had no effect or interrupted the music for 15 sec. The results showed stimulus control in all subjects and an increased discrimination between the first one‐half and last one‐half of the sessions for seven of the eight subjects.