Groups of pigeons were trained to depress a treadle in the presence of a compound stimulus consisting of a tone and a red house light (a) to avoid electric shock or (b) to obtain grain. Responding in the absence of the compound stimulus postponed its next occurrence. After performance had stabilized, the degree to which the compound and each element controlled treadle pressing was determined. In the appetitive test, many responses were made in the presence of the compound and the light alone, but very few were made to the tone alone. In the avoidance test, very few responses occurred in the presence of the light alone, an intermediate number to the tone alone, and most in the presence of the compound.

Pigeons were trained to depress a lever to avoid electric shock under free-operant avoidance schedules without a warning signal, or with a warning signal that could be terminated only by a response. Most birds in the signalled avoidance procedure terminated more than 50% of the warning signals before shock. In the unsignalled avoidance procedure, several birds formed a temporal discrimination and received relatively few shocks; other birds responded only in post-shock bursts, and received many more shocks.

Pigeons were trained to depress a treadle in the presence of a discriminative stimulus, either a tone or illumination of red houselights, in order to obtain access to grain or avoid electricshock. In avoidance training, the auditory discriminative stimulus yielded faster acquisition than did the visual one. In appetitive training, the visual discriminative stimulus yielded faster acquisition than the auditory one. Experiments 2 and 3 used these stimuli in Kamin's (1969) blocking design. In Experiment 2, when the pigeons were trained to depress a treadle in the presence of tone to obtain grain and then red light was added as the redundant stimulus, the light acquired stimulus control over treadlepressing; blocking was not observed. In Experiment 3, when the pigeons were trained to depress a treadle in the presence of red light to avoid electric shock and then tone was added as the redundant stimulus, the tone acquired stimulus control over treadlepressing. Again, blocking was not observed. The implications of these results for several models of stimulus control are discussed. 183It has been demonstrated in several paradigms that the experimenter's choice of the reinforcer determines which element of a compound conditioned stimulus or discriminative stimulus will exert the stronger control over responding, that is, there will be a stimulus-reinforcer interaction. One stimulusreinforcer interaction was observed by Foree and LoLordo (1973), who trained groups of pigeons to depress a treadle in the presenceof a compound auditoryvisual discriminative stimulus either to avoid electric shock or to obtain grain. After the pigeons were performing well, the individual elements of the compound stimulus, red houselight and a pure tone, were presented separately to assess their control of treadlepressing. In the test, the tone controlled much more responding than did the red houselight in the shock avoidance condition, but the red light controlled more responding than did the tone in the appetitive condition. Thus, the tone was the dominant stimulus in the avoidance condition, but the red light was the dominant stimulus in the appetitive condition.Kamin (1969) found that, for rats in a conditioned emotional response (CER) procedure, the occurrence of stimulus dominance following compound training could be predicted on the basis of the rates of acquisition in independent groups conditioned to the separate elements. One group of rats conditioned rapidly

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The effects of d-amphetamine on punished responding were studied in two experiments.In Experiment I, pigeons responded under a multiple fixed-ratio 30 response fixed-interval 5-min schedule of food presentation with 60-sec limited holds in both components. Each response was punished with electric shock, the intensity of which was varied systematically.In Experiment II, another group of pigeons responded under a multiple fixed-interval 5-min fixed-interval 5-min schedule of food presentation with 40-sec limited holds. Each response was punished with shock during one component, and every thirtieth response was punished in the other component. d-Amphetamine increased overall rates of punished responding only rarely under any of the punishment conditions; however, response rates within the fixed-interval when rates wvere low wvere increased by d-amphetamine when the shock intensity was low (Experinment I), or when responses produced shock intermittently (Experiment II). The data suggest that the effects of d-amphetamine on punished responding depend on the control rate of responding, the punishment intensity, the punishment frequency, and the schedule of food presentation.In a variety of situations, the effects of the amphetamines on behavior have been shown to depend on the pattern of responding (Dews, 1958a, b;Smith, 1964;Clark and Steele, 1966;McMillan, 1968McMillan, , 1969. In general, appropriate doses of the amphetamines increase low rates of responding and decrease high rates.Among several exceptions to the rate-dependent effects of the amphetamines is their effect on punished responding. Although punishing stimuli often reduce responding to very low rates, amphetamine has been reported not to increase rates of punished responding. On the contrary, it has been reported that the amphetamines reduce even further low rates of punished responding. Geller and Seifter (1960) observed the effects of amphetamine (0.5, 1.0, and 1.5 mg/kg) administered to rats working under a multiple schedule in which an unpunished variable-interval 2-min (VI 2-min) component alternated with a component in '