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PubMed1991

Dopamine and conditioned reinforcement. I. Differential effects of amphetamine microinjections into striatal subregions.

In the conditioned reinforcement paradigm, animals learn a new instrumental response reinforced solely by conditioned reward (a stimulus that has previously been associated with primary reward). It has been shown that psychostimulants potentiate responding for conditioned reward and there is evidence that the nucleus accumbens is involved in this effect. The present experiments extend this work and examine the roles of various striatal subregions in the enhancement of responding for conditioned reward. In the conditioning phase, hungry rats were trained to associate a light/click stimulus with food delivery, with no levers present in the operant chamber. In the test phase, two levers were present and responding on one provided conditioned reward (presentation of the compound stimulus but no food). During this phase, microinjections of d-amphetamine (0, 0.2, 2.0, 20.0 micrograms/0.5 microliters) were made into seven striatal subregions in separate groups of rats. Injection of amphetamine into the nucleus accumbens elicited a dose-dependent, selective increase in responding for CR. Injections into posterior regions of the striatum had no effect. Significant and selective increases in CR responding were noted after injections into two regions neighboring the nucleus accumbens, the anterior dorsal and the ventromedial striatum, although the magnitude of these effects was considerably less than that following accumbens injections. Injections into ventrolateral regions increased responding in some rats, but this effect was very variable and not selective for the CR lever. These results are interpreted as evidence for functional heterogeneity of the striatum with regard to enhancement of conditioned reinforcement. The findings are discussed in relation to the theory that increased dopaminergic activity in the nucleus accumbens results in amplification of the response to a previously learned reward-related signal.

Animals↗
PubMed1963

Amplitude-induction gradient of a small-scale (covert) operant.

An invisibly small thumb-contraction was conditioned under secondary positive reinforcement (money) in four adult human subjects without their observation of the response. Electromyo-graphic detection enabled the experimenter to reinforce the response by advancing on the subject's illuminated scoreboard the count of nickels earned. A light-beam galvanometer recorded on photosensitive paper not only those instances of the response which were of the size pre-selected for reinforcement but also those too small or too large to qualify. From the developed record cumulative response curves were constructed for each of the variously sized subclasses of the operant. Histograms, too, were plotted showing response-frequency by subclass for each 10-min interval of the experimental session. Before conditioning, response frequency was radically skewed toward the large-amplitude end of the distribution. The effect of conditioning was to normalize the distribution, with the middle-sized subclass (the one reinforced) becoming modal. This entailed reduced frequency of responses in subclasses smaller than the one reinforced. In extinction the original skew was strikingly restored in three of the four cases.

Adult↗
PubMed1979

Reinforcement contingencies as discriminative stimuli: II. Effects of changes in stimulus probability.

Three pigeons were trained on a matching procedure involving a sample component and a choice component. Responding in the sample component, according to either a differential-reinforcement-of-low-rate schedule on some trials or a differential-reinforcement-of-other-behavior schedule on other trials, produced access to the choice component in which each of two keys was illuminated with a unique color. The correct choice response was defined by the contingency that was met to produce the choice. The food hopper operated for 1.5 seconds following an appropriate sample response and for 3 seconds following a correct choice response. A signal-detection analysis showed that variations in the probability of presentation of the different contingencies systematically affected response bias but not sensitivity to the contingencies as stimuli. Substitution of a blackout for food at the end of the sample component did not differentially affect performance, but elimination of the delay between sample and choice components generally increased the sensitivity measure. The findings suggest a role for reinforcement contingency discrimination in schedule-controlled responding.

Animals↗
PubMed1984

Optimization versus response-strength accounts of behavior.

Pigeons were run in both single-key and concurrent-key experiments in which, over most of the range of response rates, an increase in response rate gave rise to a continuous decrease in reinforcement rate. In spite of the fact that a low response rate would have produced a high reinforcement rate, all birds responded at relatively high rates, thus keeping reinforcement rates substantially below the maximum possible. In the concurrent-key experiment, in addition to responding at relatively high rates, the birds' ratios of responses approximately matched the corresponding ratios of obtained reinforcers. The results are inconsistent with most theories of optimal performance, which assume that organisms behave in ways that either maximize reinforcement value or minimize deviations from a free-behavior point. On the other hand, the results are consistent with the assumption that reinforcement strengthens the tendency to respond.

Animals↗
PubMed1998

The birth of the blended curriculum.

BACKGROUND AND OBJECTIVES: In the struggle to survive economically, our family practice residency program developed a new curriculum that incorporated elements of both the conventional rotational model and the newer longitudinal mode. We also created unique elements: immersion weeks, subspecialty clinics, and Tuesday specials. Immersions weeks provide focused exposures to specialty areas. The resident brings learned skills back to the family practice clinic (FPC). Subspecialty clinics in the FPC bring specialists to the residents and to the residents' patients for reinforcement of learned skills. Tuesday specials provide longitudinal experiences in geriatric, community, and occupational medicine. The blended curriculum has been a success with both Residency Assistance Program consultants and the Residency Review Committee reviewer. It has also increased residents' availability to see patients in the FPC and increased FPC income.

Curriculum↗
PubMed1987

Choice between reliable and unreliable outcomes: mixed percentage-reinforcement in concurrent chains.

Pigeons' choices between alternatives that provided different percentages of reinforcement in mixed schedules were studied using the concurrent-chains procedure. In Experiment 1, the alternatives were terminal-link schedules that were equal in delay and magnitude of reinforcement, but that provided different percentages of reinforcement, with one schedule providing, reinforcement twice as reliably as the other. All pigeons preferred the more reliable schedule, and their level of preference was not systematically affected by variation in the absolute percentage values, or in the magnitude of reinforcement. In Experiment 2, preference for a schedule providing 100% reinforcement over one providing 33% reinforcement increased systematically with increases in the duration of the terminal links. In contrast, preference decreased systematically with increases in the duration of the initial links. Experiment 3 examined choice with equal percentages of reinforcement but unequal delays to reinforcement. Preference for the shorter delay to reinforcement was not systematically affected by variation in the absolute percentage of reinforcement. The overall pattern of results supported predictions based on an extension of the delay-reduction hypothesis to choice procedures involving mixed schedules of percentage reinforcement.

Animals↗
PubMed2001

Speed contingencies, number of stimulus presentations, and the nodality effect in equivalence class formation.

Two experiments compared performances on conditional discrimination tasks using single-participant designs with and without speed contingencies. Experiment 1 was a systematic replication of Spencer and Chase (1996). Experiment 2 presented equal numbers of training and testing trials. In each experiment, 2 female undergraduates participated. Each formed three five-member and three seven-member equivalence classes in Experiments 1 and 2, respectively. Response speed was an inverse function of nodal number and relational type in Experiment 1, but only of relational type (i.e., baseline, symmetry, transitivity, and equivalence) in Experiment 2, with and without the speed contingency. Accuracy tended to peak without the speed contingency in both experiments. Adding the speed contingency increased response speeds in both experiments, more so in Experiment 2 with a lower limited hold for I participant. The results of Experiment 2 cast doubt on previous reports of the nodality effect and on the notion of "relatedness" among class members, and they support a reinforcement-contingency, rather than a structural, account of equivalence class formation.

Adult↗
PubMed1995

An interactive histology image-barcode manual for a videodisc image library.

UNLABELLED: Cell Biology and HISTOLOGY (alias Microanatomy, alias Microscopic Anatomy) is a required course for first-year medical and dental students in most health science centers. The traditional approach used in teaching this discipline is to present photomicrographic images of structures to students in lecture using 35 mm slides of fields seen through the microscope. The students then spend many hours viewing and studying specimens of tissues using a light microscope in a laboratory setting. Students in traditional courses of histology spend an inordinate amount of time learning the component structures by attempting to find and identify them in tissue sections using a microscope, where the structure being sought is surrounded by a multitude of other structures with which they are also not familiar. With the recent availability of videodisc stored image libraries of histological samples, it is now possible to study histological principles without the use of the microscope as the primary learning tool. A videodisc entitled " HISTOLOGY: A Photographic Atlas" by S. Downing (published by Image Premastering Services Limited, Minneapolis, MN, 1991) has been incorporated into our histology course. Fifteen videodisc player stations are provided for 150 students. Images are retrieved by students using a bar code scanner attached to a videodisc player (Pioneer CLD-2400). Using this kind of image library, students can now learn basic histological structure, such as cell and tissue types, without the use of a microscope or as a tool for facilitating microscopy. The use of a videodisc library of randomly accessible images simplifies learning the basic components which all organs are composed of by presenting the learner with clear-cut examples to avoid confusion with other structures. However, videodisc players and TV monitors are still not appropriately priced for every student to own. This presents a problem in that the same images studied in class are not available to study and review outside of class. There is a need for resources for additional study outside of the institutional setting, for students to have and interact with to reinforce the learning experience in the teaching laboratory. A hard copy manual was created and is being used in our course; it incorporates photos captured from the videodisc. The images displayed in the manual are chosen to give the student one example of each histological component. Additional labeling is added to the images, and each image is accompanied by a bar code that may be used at a videodisc player with a bar code reader to retrieve the same color image from the disc displayed in larger format on a TV monitor. Each topic in the manual is accompanied by learning objectives and a statement of clinical relevance. Following the presentation of the images in each section of the manual, the students are encouraged to practice by viewing multiple examples of each structural component presented in the lesson. They can do this by using the bar-coded catalog supplied with each disc. The presentation of each topic concludes with a quiz composed of questions about images that the student can retrieve from the videodisc using barcodes in the text of the manual. Some of the images on the quiz are printed in miniature in the manual to provide the student with an opportunity for personal review at home when hardware to obtain and display images from a video disc is not available. This manual provides an answer to the dilemma faced by the learner when access to hardware is not available; reinforcement is therefore facilitated outside the teaching laboratory. This allows learning to continue outside of the classroom, using the same materials. (abstract truncated)

Computer-Assisted Instruction↗
PubMedDate not supplied

Nutriquest: a fun way to reinforce nutrition knowledge.

Gaming is an educational strategy that facilitates and reinforces student learning in a stimulating and dynamic format. The authors describe the creation and use of a nutrition review board game. The game, NUTRIQUEST, was used to reinforce the theoretical concepts of nutrition and the principles of dietary management.

Education, Nursing↗