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Three generalization procedures were used to investigate inhibitory stimulus control following discrimination learning with few errors. Three groups of pigeons acquired a discrimination between a green stimulus (the positive stimulus) and a vertical or horizontal line (the negative stimulus) through differential autoshaping followed by multiple schedule presentation of the two stimuli with gradually increasing stimulus durations. Genereralization testing was along a line‐tilt continuum. For one group, the test involved a resistance‐to‐reinforcement procedure in which responses to all line tilts were reinforced on a variable‐interval schedule. For a second group, also tested with the resistance‐to‐reinforcement procedure, the lines were superimposed on the green field that formerly served as the positive stimulus. A third group was tested in extinction with the combined stimuli. Control groups had no discrimination training but responding to green was nondifferentially reinforced. The control subjects responded more to all line tilts during testing than did the comparable experimental subjects, indicating that the negative stimulus had become an inhibitory stimulus. Both resistance‐to‐reinforcement groups revealed inhibitory gradients around the negative stimulus, but the gradient for the extinction group was relatively flat. These data are consistent with others that modify Terrace's early conclusion concerning the failure of inhibition to develop during errorless training.

The study was conducted within a training and demonstration center for teachers from several different school districts. The teachers staffing the center were employees of the host school district who volunteered to serve in the center. Unfortunately, these volunteers did not always use the program materials appropriately and therefore did not always provide clear models for visiting teachers. In particular, four of the volunteer teachers did not always instruct their students from the appropriate reading text, even when encouraged to do so by the principal of the school in which the center was located. Various procedures were employed to alter this situation. The experimenter, (associate director of the training and demonstration center) provided instructions, feedback, and praise regarding use of the appropriate reading text. These procedures had clear effects with only one teacher. Then, merit or bonus payments were provided for teachers who used the appropriate reading text for criterion periods of time; a procedure that was very effective with all four teachers. The problem worked on in this study is typical of those faced by workers in public institutions where change cannot be brought about by the researcher's authority. All teachers in the present study had the necessary skills to demonstrate accurately the prescribed program procedures, but they did not always do so until the bonus payment was used. Although the bonus payment procedure might be inappropriate in some school situations, the procedure could easily be adjusted to accommodate the established practices of many schools. For example, establishment of explicit performance criterion and use of in‐service stipends for meeting criterion performance during school hours, rather than attendance at meetings after school, might well be comparably effective.

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In Experiment I, keylight was paired with inaccessible grain delivery (under two conditions of keylight intensity) to determine if autoshaping would occur in the absence of primary reinforcement. In Experiment II, the procedure was repeated with accessible grain, for comparison. In Experiment III, the procedures were repeated with explicitly unpaired presentations of keylight and either inaccessible or accessible grain. The results indicated that key pecking occurred as quickly in the presence of keylight pairings with inaccessible grain as with accessible grain, though (except for one bird) key pecking was not maintained with inaccessible grain. Furthermore, compared to the dim keylight, the bright keylight greatly suppressed key pecking when paired with inaccessible grain, and reduced the rate of key pecking when paired with accessible grain. Little key pecking occurred in groups exposed to explicitly unpaired presentations of keylight (whether bright or dim) and grain (whether accessible or inaccessible). When the birds in Experiment III were retested with explicitly paired presentations of keylight and grain, little key pecking was observed, suggesting suppressive effects of prior explicitly unpaired presentations. It is suggested that the effects of key‐brightness manipulation were produced by the association of grain with cues other than the response key, or by distraction produced by partial illumination of the grain hopper.

Local patterns of responding were studied when pigeons pecked for food in concurrent variable‐interval schedules (Experiment I) and in multiple variable‐interval schedules (Experiment II). In Experiment I, similarities in the distribution of interresponse times on the two keys provided further evidence that responding on concurrent schedules is determined more by allocation of time than by changes in local pattern of responding. Relative responding in local intervals since a preceding reinforcement showed consistent deviations from matching between relative responding and relative reinforcement in various postreinforcement intervals. Response rates in local intervals since a preceding changeover showed that rate of responding is not the same on both keys in all postchangeover intervals. The relative amount of time consumed by interchangeover times of a given duration approximately matched relative frequency of reinforced interchangeover times of that duration. However, computer simulation showed that this matching was probably a necessary artifact of concurrent schedules. In Experiment II, when component durations were 180 sec, the relationship between distribution of interresponse times and rate of reinforcement in the component showed that responding was determined by local pattern of responding in the components. Since responding on concurrent schedules appears to be determined by time allocation, this result would establish a behavioral difference between multiple and concurrent schedules. However, when component durations were 5 sec, local pattern of responding in a component (defined by interresponse times) was less important in determining responding than was amount of time spent responding in a component (defined by latencies). In fact, with 5‐sec component durations, the relative amount of time spent responding in a component approximately matched relative frequency of reinforcement in the component. Thus, as component durations in multiple schedules decrease, multiple schedules become more like concurrent schedules, in the sense that responding is affected by allocation of time rather than by local pattern of responding.

The maintenance of a response controlling the duration of positive and negative discriminative stimuli in a multiple schedule was examined with respect to the possible consequences of the response: none, escape from the negative stimulus, production of the positive stimulus, and initiation of the reinforcement schedule associated with the latter. The last two seemed to be the major factors in producing and maintaining the response. Escape from the negative stimulus maintained it in most subjects, but only at a much lower level.