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PubMed2006

Infrequent, but not frequent, reinforcers produce more variable responding and deficient sustained attention in young children with attention-deficit/hyperactivity disorder (ADHD).

BACKGROUND: The underlying behavioral/psychological processes of attention-deficit/hyperactivity disorder are unclear. Motivational factors, related to dopamine dysfunction, may play an important role in the development of the behavioral symptoms. Particularly, infrequent, but not frequent, reinforcers have been suggested to be associated with altered responding and deviant behavior in children with ADHD. The present study was designed to analyze the influence of reinforcement frequency on operationalized measures of hyperactivity, impulsiveness, sustained attention, and response variability. METHODS: Fifty-six boys, half of whom were diagnosed with ADHD, completed a computerized task presented as a game with two squares on the screen. One square was associated with reinforcement. The task required responses by the computer mouse under contingencies alternating between variable interval schedules of short (mean 2 s) and long (mean 20 s) durations. Reinforcers were cartoon pictures and small trinkets. RESULTS: Overall, there was no difference between children with ADHD and comparison children when reinforcers were given frequently. Statistically significant differences on measures of sustained attention and variability, but not hyperactivity and impulsiveness, were found during infrequent reinforcement only. Age effects interacted with group effects on sustained attention, showing that group differences were found in the young children only. Surprisingly, older comparison children showed increased response variability and no learning. CONCLUSIONS: When reinforcers are infrequent, children with ADHD show deficient sustained attention and increased variability in responding. Computer experience may have interfered with measures of hyperactivity and impulsiveness. The unexpectedly poor performance of the older comparison children may have been due to inefficient reinforcers or to verbally governed behavior overruling reinforcer effects. Reinforcer characteristics and experimental procedures are important factors influencing findings in studies investigating motivational factors. The study provides some support for the dynamic developmental theory of ADHD predicting relationships between neurobiological deficits, altered reinforcement mechanisms, and treatment recommendations.

Age Factors↗
PubMedDate not supplied

[Instrumental and classical reflexes with water reinforcement].

Thirsty dogs were learned to regulate the supply of water by flexing the paw. The movement was effective only during an acoustic stimulation, either immediately at its beginning, or 10 to 20 sec. after its isolated action. The acoustic signal produced both flexion of the paw (instrumental reflex) and rhythmic swallowing movements which preceded the moment when water was fed into the mouth (classical conditioned reflex). The effect of prolongation of the isolated acoustic stimulation was manifested with extinction of the classical conditioned reflex and activation of the instrumental one.

Animals↗
PubMed2006

Amygdala response to facial expressions reflects emotional learning.

The functional role of the human amygdala in the evaluation of emotional facial expressions is unclear. Previous animal and human research shows that the amygdala participates in processing positive and negative reinforcement as well as in learning predictive associations between stimuli and subsequent reinforcement. Thus, amygdala response to facial expressions could reflect the processing of primary reinforcement or emotional learning. Here, using functional magnetic resonance imaging, we tested the hypothesis that amygdala response to facial expressions is driven by emotional association learning. We show that the amygdala is more responsive to learning object-emotion associations from happy and fearful facial expressions than it is to the presentation of happy and fearful facial expressions alone. The results provide evidence that the amygdala uses social signals to rapidly and flexibly learn threatening and rewarding associations that ultimately serve to enhance survival.

Adult↗
PubMed1965

TEMPORAL ALTERNATION IN THE WHITE RAT.

Four white rats were reinforced after 15 then 45 then 15 then 135 (or 5) responses to a bar under a single exteroceptive stimulus condition. Three came to make long pauses before the longest ratio in the schedule but not before any of the others. Four other rats were reinforced after alternate response chains each made on two bars. The first chain was FR5FR5 for all subjects, the second FR5FR40 for two, and FR40FR5 and FR20FR5 for one subject each. Subjects reinforced on schedule mix (chain FR5FR5 chain FR5FR40) both paused longer after the first than after the second chain relatively early in training. Later, the subject reinforced on mix (chain FR5FR5 chain FR40FR5) also paused longer after the first chain, but pauses of the fourth subject were equally short after both chains. When the ratios in the second chain were reversed the two subjects now reinforced on mix (chain FR5FR5 chain FR40FR5) paused much longer after the first chain, but the other two paused only slightly longer after the first than after the second chain.

Discrimination Learning↗
PubMed1965

SEQUENTIAL RESPONSE EFFECTS IN THE WHITE RAT DURING CONDITIONING AND EXTINCTION ON A DRL SCHEDULE.

Sequential IRT data were obtained for three rats on a DRL 60-sec reinforcement schedule. It was found that first-order sequential dependencies exist under this schedule, including the partial dependence of the length of any given IRT on the length of the preceding IRT. The sequential analysis also served to extend the finding in the literature, based on frequency distributions, that the likelihood of a reinforced IRT is greater after a reinforced IRT than a non-reinforced IRT. Rapid extinction and reconditioning were obtained.

Extinction, Psychological↗
PubMed1965

OBSERVABLE CHANGES OF HYPOTHESES UNDER POSITIVE REINFORCEMENT.

In mathematical models of concept learning it has consistently been assumed that positive reinforcement cannot lead to a change of the hypothesis determining the overt response. When hypotheses are experimentally identified and recorded along with positive and negative reinforcements of stimulus-response pairs, it can be shown that hypotheses may change after a positive reinforcement. Positive reinforcement has an information content for subjects that has not yet been adequately recognized in concept formation studies.

Humans↗
PubMed1980

Motivational role of social reinforcement in dog-man relations.

Lesions of dorsomedial amygdala (DMA) or lateral hypothalamus (LH) produced prominent impairment of the alimentary behavior in dogs. Besides, various behavioral responses, including social, were depressed. To evaluate whether these changes were either specific for alimentary disturbances or dependent on changes in the general reward system, another type of reward, i.e. social contact with experimenter as a reinforcement for several motor responses was introduced. Damage of amygdalo-hypothalamic system, which produced a syndrome of depression, also impaired socially reinforced responses. This impairment lasted much longer then decrease of food intake. Therefore it was assumed that DMA and LH damage produced impairment not limited to alimentary mechanisms, but involving various aspects of positive motivational system and in particular including the social behavior during man-dog relations. Taking into account various theories of reinforcement in instrumental learning the authors are inclined towards a hedonistic theory of reward.

Amygdala↗
PubMed1963

A comparison of several procedures for eliminating behavior.

The pecking response of pigeons was reinforced when a minimum period of time had elapsed since the last response (DRL schedule of food-reinforcement). Punishment, satiation, extinction, and stimulus change were employed separately to reduce responding. When the effects of the four procedures were compared, punishment was found capable of producing a more immediate, complete and long lasting response reduction than the others. Punishment had its maximum effect on the responses that were least relevant to reinforcement. The punishment reduced the frequency of the short inter-response times to a greater extent than did either extinction or satiation. In this way, punishment actually increased the efficiency of the DRL responding.

Animals↗
PubMed2003

Isotropic sequence order learning.

In this article, we present an isotropic unsupervised algorithm for temporal sequence learning. No special reward signal is used such that all inputs are completely isotropic. All input signals are bandpass filtered before converging onto a linear output neuron. All synaptic weights change according to the correlation of bandpass-filtered inputs with the derivative of the output. We investigate the algorithm in an open- and a closed-loop condition, the latter being defined by embedding the learning system into a behavioral feedback loop. In the open-loop condition, we find that the linear structure of the algorithm allows analytically calculating the shape of the weight change, which is strictly heterosynaptic and follows the shape of the weight change curves found in spike-time-dependent plasticity. Furthermore, we show that synaptic weights stabilize automatically when no more temporal differences exist between the inputs without additional normalizing measures. In the second part of this study, the algorithm is is placed in an environment that leads to closed sensor-motor loop. To this end, a robot is programmed with a prewired retraction reflex reaction in response to collisions. Through isotropic sequence order (ISO) learning, the robot achieves collision avoidance by learning the correlation between his early range-finder signals and the later occurring collision signal. Synaptic weights stabilize at the end of learning as theoretically predicted. Finally, we discuss the relation of ISO learning with other drive reinforcement models and with the commonly used temporal difference learning algorithm. This study is followed up by a mathematical analysis of the closed-loop situation in the companion article in this issue, "ISO Learning Approximates a Solution to the Inverse-Controller Problem in an Unsupervised Behavioral Paradigm" (pp. 865-884).

Algorithms↗
PubMedDate not supplied

The relationship between reinforcement and memory: parallels in the rewarding and mnemonic effects of the neuropeptide substance P.

A theory of reinforcement is presented which accounts for the backward action of a reinforcer on operant behavior in terms of its effect on memory traces left by the operant. Several possible ways in which a reinforcer could strengthen the probability of recurrence of an operant are discussed. Predictions from the model regarding general memory-promoting effects of reinforcers presented posttrial in various learning paradigms are outlined. The theory also predicts a parallelism in reinforcing and memory-promoting effects of stimuli, including drugs. The second part of the chapter outlines experiments investigating memory modulating and reinforcing effects of the neuropeptide substance P. In general, injection of SP is positively reinforcing when injected into parts of the brain where it has been shown to facilitate learning. Peripheral injection of SP is also reinforcing at the dose known to promote passive avoidance learning when presented posttrial.

Amino Acid Sequence↗
PubMedDate not supplied

[The concept of reinforcement in research on simple nervous systems].

Analysis of applicability of the reinforcement concept to the learning studies in invertebrate systems is performed basing on literature and own data. It is suggested that reinforcement can be regarded not as an independent phenomenon, but as a state of the nervous system which precedes a long-term changes of behavior. Such consideration of reinforcement allows to use this concept in studies of plasticity and learning in simple nervous systems, investigate neurochemical mechanisms of reinforcement.

Animals↗
PubMed2001

Computer assisted learning. A review.

Since 1980 the amount of medical information has doubled approximately every second year. This implies that oral health students as well as professionals need to manage the flow of information rationally, in order to learn how to undertake evidence-based decision-making for diagnosis and treatment in a given patient situation. Current research indicates that computer connected databases and computer assisted learning (CAL) may enhance learning and provide the clinician with information for decision-making when treating patients. Multimedia for CAL, which combines audio and visual data in an interactive form, has proved to be an effective tool in education. CAL may supplement and reinforce more traditional learning and create opportunities to illustrate clinical situations in an interactive way. CAL has the potential to help students develop skills and knowledge. Students, staff and professionals consider CAL stimulating and motivating. Students easily adapt to CAL although their current computer literacy is still low. New authoring tools make it easier for faculties to develop their own CAL software. In the future we will see more sophisticated software with virtual patients who can communicate and interact with the student in a very realistic way. The software will even "step out" from the screen and help the student with clinical procedures. However, at present CAL should not replace traditional education, but rather be used more as a supplement and for self-directed studies.

Attitude↗
PubMed1962

Effects on deprivation and reinforcement-magnitude of response variability.

Animals were trained to displace any one of five response keys in order to put themselves in a stimulus condition in which reinforcement could be obtained by depressing a response lever. Decreased deprivation and magnitude of reinforcement were found to increase the variability of the distribution of key responses. The relevance of these findings to other experiments in which deprivation, reinforcement magnitude, and intermittent reinforcement were studied is discussed.

Animals↗