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Biomedical subjects

J Zimmerman

Publications and source records attributed to J Zimmerman.

At least 181 records · Page 10Linked to original sources
PubMed1969

Differential effects of token reinforcement on instruction-following behavior in retarded students instructed as a group.

This study was addressed to the problem of applying behavior modification techniques on a group basis to a class of retarded students with "attentional deficits". Seven boys, age 8 to 15 yr, characterized as showing severe "attentional" problems or disruptive behavior in their respective classrooms, participated daily for 30-min sessions in a special class over a 1.5-month period. In each session, verbal instructions were given to the class as a whole. In control sessions, each appropriate instruction-following response by a child produced praise for that child. In experimental sessions, appropriate responses also produced tokens exchangeable for tangible reinforcers after the session. Token reinforcement differentially maintained instruction-following behavior in four children while one responded appropriately to most instructions and a second improved continuously during the study. While the data suggest that the present approach can be successfully applied to the alteration of instruction-following behavior in retarded children, its major contribution may be that of providing objective quantitative information about such behavior.

Journal Article↗
PubMed1967

Effects of conditioned reinforcement frequency in an intermittent free-feeding situation.

Key-pecking intermittently produced a set of brief exteroceptive stimulus changes under two-component multiple schedules of conditioned reinforcement. Throughout the study, free access to grain was concurrently provided on an intermittent basis via a variable-interval tape. Free food presentations scheduled by the tape were delivered if no peck had been emitted for 6 sec, and the brief stimulus changes produced by responding under the multiple schedules were those which accompanied food presentation. The second component of each multiple schedule was always associated with a 1-min, variable-interval schedule of conditioned reinforcement. The schedule associated with the first component was systematically varied and conditioned reinforcement was either absent (extinction) or programmed on a 1-, 3-, 6-, or 12-min variable-interval schedule. Under these conditions, rate of responding in the manipulated component decreased monotonically with a decrease in the frequency of conditioned reinforcement. In addition, contrast effects were often obtained in the constant, second component. These results are similar to those obtained with similar multiple schedules of primary reinforcement.

Animals↗
PubMed1966

The effects of a pre-time-out stimulus on matching-to-sample of humans.

In each of two experiments human subjects were intermittently reinforced with money on a fixed-ratio schedule for emitting correct matching responses. A pre-time-out stimulus which signaled removal of positive reinforcement was periodically superimposed. In the first experiment the superimposed pre-time-out stimulus was paired with a 1-min or 4-min response-independent time out. In the second experiment the pre-time-out stimulus was paired with a 1-min or 4-min time out contingent on the incorrect responses. The pre-time-out stimulus did not markedly influence performance when the time out was response independent. In contrast, the pre-time-out stimulus markedly suppressed incorrect responding when the time out was contingent on the incorrect responses. When duration of this time-out was increased from 1-min to 4-min, suppression of incorrect responding increased and correct responding was suppressed. Therefore, behavioral suppression by a pre-time-out stimulus was obtained only when the signaled aversive event-time out-was response produced. In this case, suppression was influenced by time-out duration.

Behavior↗
PubMed1966

Second-order avoidance behavior in monkeys.

Two monkeys were trained on a three-component multiple schedule using discrete trials. In one component (food), a response terminated a red stimulus and produced food and S(Delta). In the second component (avoidance), a response terminated a green stimulus and avoided shock. In the third component (optional), a response terminated a blue stimulus and produced S(Delta). The consequence of not responding in the blue stimulus, however, was the production of either a food or an avoidance trial. Manipulation of these consequences showed that when food trials were available only a small percent of the time after optional trials, the subjects tended not to respond in the blue, even though this led to an increase in the total number of avoidance trials per day. If only avoidance trials followed as a consequence of not responding in the optional component, the animals terminated the blue stimulus and avoided the avoidance trials. Throughout the experiment both subjects maintained consistently low shock rates (about 10 per day) and these were not affected by the various manipulations. The data suggest that a stimulus associated with avoidance can be a conditioned aversive stimulus and will maintain a more remote avoidance response under certain conditions.

Animals↗
PubMed1962

The alteration of behavior in a special classroom situation.

Unproductive classroom behavior was eliminated in two emotionally disturbed boys by removing social consequences of the behavior. Behavior which was more adequate and efficient with respect to social and scholastic adjustment was shaped and maintained with social reinforcers.

Journal Article↗
PubMedDate not supplied

Effect of weight loss in moderate obesity on plasma lipoprotein and apolipoprotein levels and on high density lipoprotein composition.

Plasma lipids, lipoprotein and apolipoprotein levels were determined in seven women and seven men with moderate obesity before, during 7 weeks of continuous weight loss (10.4% to 9.6% of body weight, 1000 kCal/day diet), and after 3 months at a stable, reduced weight. Plasma triglyceride levels decreased by 30.4% in men and by 39.4% in women (p less than 0.0001) after 1 week of caloric restriction and remained at this level throughout the study period. The plasma cholesterol decreased by 19.0% in men (p less than 0.001) and by 10.9% in women (p less than 0.01) in the period of active weight loss, but returned to prediet values after stabilization at a leaner body mass. Similar changes were observed in LDL cholesterol levels. No change in high density lipoprotein (HDL) cholesterol levels occurred during active weight reduction, but after 3 months at a reduced weight, a significant increase in HDL cholesterol was evident, and the ratio of HDL cholesterol to plasma cholesterol increased over prediet values (p less than 0.001), women). Separation of HDL subpopulations by zonal ultracentrifugation before and after weight reduction revealed that HDL2 increased slightly in men and decreased slightly in women. In both genders, HDL3 tended to decrease after weight reduction. Plasma levels of apolipoprotein A-I decreased during active weight loss, but this was significant only in women (p less than 0.05). After 3 months of reduced weight, plasma apo A-I increased to prediet levels. No significant changes in plasma apo A-II or apo E were noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Reconstruction of the cardiac valves with autologous tissue.

A rather long and extensive experience with tissue reconstruction in patients with mitral valve disease, and a much less extensive one with oartic lesions, has convinced us of the superiority of the presented techniques of reconstruction, and of the preferability of fascia lata over all other tissues so far tried for this purpose. Despite an early increment of shrinkage of the order of about 30% of each linear measurement, late studies of fascia lata removed from reconstructed valves after several years (over five) indicate no loss of cellularity and no measurable loss of tissue strength or flexibility. Late calcification was not observed in any of our baboons, although it appears to be a consistent development in dogs. It has been seen in only one patient (after four years) to date. It is now believed that we can offer prolonged clinical benefit approaching actural "cure" to many of the younger patients who otherwise would have no recourse but to prosthetic palliation. It is true that recently Willen, Dubiel and Johansson (50, 51), Gersbach and Wegmann (52), and Senning and Rothlin (53) have demonstrated that repetitive deposits of fibrin upon the surfaces of fascia lata implanted within the cardiovascular chambers lead to progressive encapsulation with organizing connective tissue (scar). At some time period following surgery, closer to 10 years than to 5, degeneration of the fascia takes place, presumably due to "strangulation" by the organized exudate which interrupts the "normal" mechanism of its nutrition which is based upon diffusion from the flowing blood. The recent contributions of Sullivan, Harken and Gorlin (54), Weily and Genton (55), and Harker and Slicter (56) to our understanding of the role of the platelets in initiating such fibrinous deposition now provide us with a way to prevent such late degeneration of valves made of fascia lata. The regular administration of platelet dispersing agents (aspirin, Persantin, or inderol) in ordinary therapeutic dosage would seem to be completely protective. Undoubtedly, anticoagulant therapy would be equally effective. However, the permanent maintenance of a proper level of "anti-coagulation" such as is usually deemed necessary following implantation of a prosthetic heart valve is a heavy psychological and biological burden for a patient to bear. Many such individuals live precariously between the risks of thromboembolism and the risks of hemorrhage. Thromboembolism really only represents a farther point along the spectrum of the readiness of fibrin accumulation following initial platelet aggregation and deposition. Since frank thromboembolism appears "never" to follow intracardiac implantation of fascia lata, it would seem that platelet dispersive therapy sould suffice in such cases.

Aortic Valve↗