Control of responding by location of auditory stimuli: adjacency of sound and response.

Four rhesus monkeys were trained to respond on one key when a one-second noise burst was presented through one speaker and to respond on a second key when the noise burst was presented through a second speaker. The acquisition of stimulus control was studied under three conditions, in each of which the relationship between the sound source and the response-key positions varied: an adjacent condition in which the noise burst was presented through the key and a response on this key was reinforced; a reversed-adjacent condition in which the noise burst was presented through one key and responding on the other key was reinforced: and a nonadiacent condition in which responding on the key nearer the sound was reinforced. Under adjacent conditions, stimulus control developed within one or two sessions. Under reversed and nonadjacent conditions, 10 sessions were required for the development of control. The asymptote of correct responding was the same under each condition in all animals.     

Control of pigeons' pecking by trace stimuli

In Experiment I, pigeons' pecking a white key was reinforced with grain when white was immediately preceded by a vertical white line on a green surround, but not by green alone. This procedure produced control of pecking by the line. Next, pecking white was reinforced after vertical line on green, but not after green alone or other orientations of the white line on green. The line-tilt dimension initially did not control pecking, a result that showed that interdimensional (line versus no line) training does not always result in dimensional control. Line-tilt control was eventually established but was accompanied by a decrease in interdimensional control. In Experiment II, interdimensional training, with or without a trace interval intervening between line on green or green alone and white, was followed by tests for line-tilt control. While interdimensional control was unaffected by the trace interval, line-tilt control tended to be less with the trace interval. This dissociation of interdimensional and dimensional control, as well as the failure of interdimensional training to produce dimensional control in Experiment I, suggests that the line stimulus is multidimensional.     

Positive contrast, negative induction, and inhibitory stimulus control in the rat

In Experiment I, 24 rats were trained on a multiple variable-interval variable-interval schedule with a doorlight and white noise serving as component cues. Two groups were then shifted to a multiple extinction variable-interval schedule, and a third group was maintained on the multiple variable-interval variable-interval schedule. The multiple extinction variable-interval condition produced positive contrast when either the light or noise signalled extinction, and both of these cues acquired inhibitory stimulus control as measured by a combined cue test. In Experiment II, the multiple variable-interval variable-interval condition was shifted to multiple extinction variable-interval for one group, to multiple variable-time variable-interval for a second group, and was unchanged for the third group. The two experimental conditions produced identical patterns of response-rate reduction in the altered component, but the multiple extinction variable-interval condition produced positive contrast, whereas the multiple variable-time variable-interval condition did not. Subsequent combined cue and resistance to reinforcement tests revealed that the cue signalling extinction acquired stronger inhibitory stimulus control than the cue signalling variable time.     

Signalled free-operant avoidance of shock by pigeons pecking a key

Two pigeons were trained to peck a key under a free-operant avoidance schedule. Then, changes in key color signalled the beginning (safe period) and the end (warning period) of the response-shock interval, with a response required to change the key color. Finally, a change in key color signalled the warning period and either a response or a shock reinstated the safe stimulus. During signalled avoidance, response rate was higher during the warning stimulus than during the safe stimulus. More responding tended to occur in the warning stimulus when it was terminated by either a response or a shock than by only a response. In either procedure, response latency during the warning stimulus was a function of the duration of the warning stimulus. In general, response and shock rate were higher during unsignalled than during signalled avoidance. When the warning stimulus was brief, the results were similar to those of unsignalled avoidance. These results confirm previous findings with pigeons, are in general agreement with data provided by other species in studies of signalled avoidance, and thereby indicate the transituationality of the key-pecking operant.     

Choice, time allocation, and response rate during stimulus generalization

Six pigeons were trained to discriminate between two noise intensities using a procedure that assessed choice, time allocation, and response rate simultaneously and independently. Responses on the left or right key (R1 or R2) were respectively correct in the presence of two different intensities, S1 and S2. After a correct response, reinforcement became available for pecks on the center key. Reinforcement density for R1¦S1 relative to R2¦S2 was varied across experimental conditions. Generalization tests followed extensive training at each condition. As a function of stimulus intensity, proportions of initial choices of R2, of time spent in R2-initiated components, and of center-key responses emitted in R2-initiated components all yielded sigmoidal gradients of similar slope, which shifted slightly in location when relative reinforcement density changed. Changeovers were maximal where initial choice proportions approximated 0.5. Gradients relating the absolute number of center-key responses to stimulus intensity were also roughly sigmoidal, but were more sensitive to changes in reinforcement density. Gradients of momentary response rate also depended on reinforcement density. During training, large but transitory shifts in choice responding occurred when reinforcement density changed, while differences in momentary response rate developed slowly, suggesting separate control of choice and response rate by the contingencies of reinforcement.     

The nature of control by spoken words over visual stimulus selection.

Eight retarded adolescents were trained to select one (a trained S+) of two visual stimuli in response to a spoken word (a trained word). Two different visual stimuli alternated randomly as the S-. To determine if the spoken work was merely a temporal discriminative stimulus for when to respond, or if it also specified which visual stimulus to select, the subjects were given intermittent presentations of untrained (novel) spoken words. All subjects consistently selected the trained S+ in response to the trained spoken word and selected the previous S- in response to the untrained spoken words. It was hypothesized that the subjects were responding away from the trained S+ in response to untrained spoken words, and control by untrained spoken words would not be observed when the trained S+ was not present. The two visual S- stimuli selected on trials of untrained spoken words were presented simultaneously. The untrained spoken words presented on these trials no longer controlled stimulus selections for seven subjects. The results supported the hypothesis that previous control by spoken words was due to responding away from the trained S+ in response to untrained spoken words.     

EMPLOYING TASK ARRANGEMENTS AND VERBAL CONTINGENCIES TO PROMOTE VERBALIZATIONS BETWEEN RETARDED CHILDREN1

This study investigated the effects of arranging task events for interdependence, to increase the probability of social responding. During task interdependence, the subjects, participating in dyads and a four-person group, obtained task materials (a puzzle piece) from their partner before completing their task (appropriately placing the puzzle piece). The verbal contingency required a verbal request to precede a subject's receiving a task material from his partner. The verbal contingency yoked with task interdependence made task completion contingent on the appropriate verbalization. The findings from two experiments suggested that task interdependence was sufficient to increase partner-directed verbalizations for three of the four subjects. When the verbal contingency was added, all subjects increased their requests and other verbalizations to partner. Applied to a four-person group, the verbal contingency yoked with varying levels of task interdependence correspondingly affected the pattern and level of group communications. The greater the task interdependence, i.e., the more members each subject depended on to complete his task, the more complex the social network of verbal contacts, and the higher the level of both requests and other verbalizations for the group.     

THE GENERALIZATION EFFECTS OF PARENT TRAINING ACROSS STIMULUS SETTINGS

Five parents of nonverbal children were trained in two home settings to modify antecedents and consequences to their children's vocalizations. Generalization effects of the parent training on both the parent's and children's behaviors under different stimulus conditions were investigated using multiple-baseline designs. Increases in parent prompting and reinforcing their children's vocalizations generalized only minimally to a new setting in the home where parent training had not occurred. Child increases in vocalizations produced by the parents in the training settings did generalize to this new setting in the home. There was minimal generalization of child vocalizations to a free-play setting at school. In a formal speech session conducted by a behavior specialist at school, only one child showed definite increases in acquisition rate as a function of the parents starting to train the sound at home.     

SHORT- AND LONG-TERM EFFECTS OF CONTINGENCY MANAGED INSTRUCTION ON LOW,MEDIUM, AND HIGH GPA STUDENTS1

Undergraduate students had been assigned to a contingency managed course or a conventional lecture course (Du Nann and Fernald, Journal of Applied Behavior Analysis, 1976, 9 , 373–374). Two years later, some 35% (N = 86) of the original classes responded to a letter offering them $2.00 to participate in a study of their educational experiences. These students completed a multiple-choice test on material from the course, and answered questions about activities and attitudes that might have been affected by the experience in Introductory Psychology. In the contingency management course 2 yr past, students were tested each week on a chapter of textbook material with 10-item multiple-choice quizzes. The course employed a modified “Doomsday Contingency”, requiring each student to achieve 80% mastery on one of the four weekly quizzes or drop the course. Quizzes were given in small groups and scored individually, while the student stood near, by an undergraduate proctor assigned to that group. The proctor was asked to show interest in the students' quiz performances, help clear up difficult areas, and develop a friendly working relationship with each student. While many students passed the quiz on the first attempt, others were given individual tutoring, so that no one was in fact forced to drop the course. In addition to the weekly quiz assignment, students in the contingency managed group were asked to attend one lecture each week. While the contingency management course procedures had much in common with PSI (Keller, Journal of Applied Behavior Analysis, 1968, 1 , 79–89), several departures made them unique. First, self-pacing was curtailed because students were required to master one unit per week or drop the course. Second, proctors met with students in small groups, usually giving individual tutoring only to those students who did not pass the quiz on the first attempt. Finally, students were asked to attend one lecture per week. Students in the conventional lecture group were not asked to pass weekly quizzes, but instead attended three 50-min lectures each week. Two of these lectures followed the textbook material closely, while the third, which was also attended by students from the contingency management course, covered material only indirectly related to the text. This partition of lecture content allowed material to be similar across the two instructional groups. Although students in the lecture condition were told they could obtain copies of the quizzes, few of them did so. Course grades were determined by scores on two 45-item multiple-choice hourly exams, each covering half the semester material (each worth 25%), and by a 90-item final exam, which served as a measure of short-term retention. Before analyzing the follow-up data, several characteristics of the returning students were compared to determine the comparability of the sample from the two original classes. Most important, both attrition and the current mean GPAs of students from the two classes were very similar. These considerations, and others, suggested there was no systematic sampling bias to confound comparisons of student performance. A 2 (contingency management versus traditional lecture) by 3 (high, medium, and low GPA) analysis of variance was computed on the course final-exam scores and the follow-up measures. Instructional procedure and GPA interacted on the final exam such that low and medium GPA students performed significantly better under contingency management, but there was no significant effect of instructional procedure with high GPA students. On the 2-yr retention measures, students from the contingency management course performed significantly (p < 0.01) better on items drawn from quizzes used in their original course, and marginally better (p < 0.10) on items drawn from the final exams, but no interactions with GPA appeared. Furthermore, instructional method produced no significant main effects or interaction with how many students became majors or minors in psychology, how many psychology courses were later taken, how many books in psychology were reported to have been read, or on students' evaluation of the interest and importance of psychology.     

TEACHING PEDESTRIAN SKILLS TO RETARDED PERSONS: GENERALIZATION FROM THE CLASSROOM TO THE NATURAL ENVIRONMENT1

Little attention has been given to teaching adaptive community skills to retarded persons. In this study, five retarded male students were taught basic pedestrian skills in a classroom. Training was conducted on a model built to simulate city traffic conditions. Each subject was taught five specific skills involved in street crossing in sequence, viz. intersection recognition, pedestrian-light skills, traffic-light skills, and skills for two different stop-sign conditions. Before, during, and after training, subjects were tested on generalization probes on the model and under actual city traffic conditions. Results of a multiple-baseline design across both subjects and behaviors indicated that after receiving classroom training on the skills, each subject exhibited appropriate pedestrian skills under city traffic conditions. In addition, training in some skills appeared to facilitate performance in skills not yet trained.