Effects Of Reinforcement Rate Research Articles

Investigation of machinability properties of aluminium matrix hybrid composites

In this study, machinability properties of aluminium matrix boron carbide (B 4 C) and carbon nanofiber (CNF) reinforced hybrid composite material produced by powder metallurgy in drilling were investigated. In the study, the samples produced with hot pressing technique having 6 different volume rates were used. The drilling operations were performed using drills with 3 point angles (90°–118°–135°) at 30–45-67.5 m/min cutting speed and 0.1–0.15–0.225 mm/rev feed rate. As a result of the experiments, the thrust force, moment, and surface roughness were measured and the delamination factor forming at hole exits was calculated. In addition, the effect of reinforcement rate on the machinability was also investigated. In all drill types, it was determined that as the feed rate increased, the thrust force increased and as the reinforcement rate increased, moment values also increased. Surface roughness values increased with the increased feed rate but decreased as the cutting speed increased. As the drill point angle increased, the surface roughness value decreased but the hole exit damage increased. • Low volume rate carbon nanofiber reinforcement had a positive effect on machinability properties. • As the drill point angle increased, the surface roughness value decreased but the hole exit damage increased. • Surface roughness decreased with the increase in the amount of reinforcement. • The two most effective parameters in hole exit damage are the point angle and feed rate.

Delay of reinforcement versus rate of reinforcement in Pavlovian conditioning.

Conditioned stimulus (CS) duration is a determinant of conditioned responding, with increases in duration leading to reductions in response rates. The CS duration effect has been proposed to reflect sensitivity to the reinforcement rate across cumulative exposure to the CS, suggesting that the delay of reinforcement from the onset of the cue is not crucial. Here, we compared the effects of delay and rate of reinforcement on Pavlovian appetitive conditioning in mice. In Experiment 1, the influence of reinforcement delay on the timing of responding was removed by making the duration of cues variable across trials. Mice trained with variable duration cues were sensitive to differences in the rate of reinforcement to a similar extent as mice trained with fixed duration cues. Experiments 2 and 3 tested the independent effects of delay and reinforcement rate. In Experiment 2, food was presented at either the termination of the CS or during the CS. In Experiment 3, food occurred during the CS for all cues. The latter experiment demonstrated an effect of delay, but not reinforcement rate. Experiment 4 ruled out the possibility that the lack of effect of reinforcement rate in Experiment 3 was due to mice failing to learn about the nonreinforced CS exposure after the presentation of food within a trial. These results demonstrate that although the CS duration effect is not simply a consequence of timing of conditioned responses, it is dependent on the delay of reinforcement. The results provide a challenge to current associative and nonassociative, time-accumulation models of learning.

RELATIVE REINFORCER RATES AND MAGNITUDES DO NOT CONTROL CONCURRENT CHOICE INDEPENDENTLY

One assumption of the matching approach to choice is that different independent variables control choice independently of each other. We tested this assumption for reinforcer rate and magnitude in an extensive parametric experiment. Five pigeons responded for food reinforcement on switching-key concurrent variable-interval variable-interval schedules. Across conditions, the ratios of reinforcer rates and of reinforcer magnitudes on the two alternatives were both manipulated. Control by each independent variable, as measured by generalized-matching sensitivity, changed significantly with the ratio of the other independent variable. Analyses taking the model-comparison approach, which weighs improvement in goodness-of-fit against increasing number of free parameters, were inconclusive. These analyses compared a model assuming constant sensitivity to magnitude across all reinforcer-rate ratios with two alternative models. One of those alternatives allowed sensitivity to magnitude to vary freely across reinforcer-rate ratios, and was less efficient than the common-sensitivity model for all pigeons, according to the Schwarz-Bayes information criterion. The second alternative model constrained sensitivity to magnitude to be equal for pairs of reinforcer-rate ratios that deviated from unity by proportionately equal amounts but in opposite directions. This model was more efficient than the common-magnitude-sensitivity model for 2 of the pigeons, but not for the other 3. An analysis of variance, carried out independently of the generalized-matching analysis, also showed a significant interaction between the effects of reinforcer rate and reinforcer magnitude on choice. On balance, these results suggest that the assumption of independence inherent in the matching approach cannot be maintained. Relative reinforcer rates and magnitudes do not control choice independently.

The matching law and effects of reinforcer rate and magnitude on choice in transition

Four pigeons responded in a concurrent-schedule procedure in which reinforcer rates and magnitudes changed unpredictably across sessions according to independent random series. Programmed relative reinforcement rates and magnitudes were always either 2:1 or 1:2. Pigeons' response allocation tended to stabilize within sessions and multiple regression analyses showed that it was determined by rates and magnitudes from the current session. Sensitivity coefficients were positive and statistically significant for current-session reinforcement and magnitude ratios. Although there were individual differences in sensitivity to rate and magnitude, their interaction was not significant across subjects. Rate and magnitude both controlled responding in single sessions and individual interreinforcer intervals. Analyses of responding within sessions showed that preference was more extreme when the richer rate and larger magnitude were associated with the same alternative than when they were associated with different alternatives. Overall, results support the concatenated generalized matching law's assumptions of additivity and independence as applied to choice in transition.

Demonstrations and Applications of the Matching Law in Education

Within educational settings, at any given moment students may choose to engage in assigned academic tasks or other in non-educational activities. The matching law describes and predicts choice behavior. Researchers have used the principles of the matching law to investigate the effects of reinforcement rate, quality, and immediacy as well as response effort on student choice behavior. Results have produced a knowledge base that may allow educators to increase the probability of students choosing to engage in assigned tasks. In the current paper, matching theory and research is reviewed along with descriptions of strategies and procedures that can be used to alter students' behavior within classroom environments. Directions for future applied and application research are provided.

Delivering Different Reinforcers in Each Half of the Session: Effect of Reinforcement Rate

Previous research (Weatherly, Stout, Rue, & Melville, 2000) has shown that rats’ rates of lever pressing for low-concentration liquid-sucrose reinforcement in the first half of an experimental session are higher when food pellets, rather than the same sucrose reinforcers, are delivered in the second half of the session (i.e., induction). The present study investigated whether this effect was sensitive to changes in the rate of reinforcement in the first or second half of the session. Rats responded in 50-min sessions, with 1 % (Experiment 1) or 5% (Experiment 2) liquid-sucrose reinforcers delivered during the first half of the session. In different conditions, food pellets or the same sucrose served as the reinforcer in the second half of the session. Rate of reinforcement in either the first or second half of the session was varied across conditions. Results showed that induction was present in both experiments, although it was most reliable when subjects responded for 1 % sucrose. They also suggest that rate of sucrose reinforcement is not a determining factor of when induction will be observed. By doing so, the present results increase the generality of the present induction effect.

The Influence of the Pace of Teacher Attention on Preschool Children's Engagement

Children in group-care settings often require reinforcement in the form of teacher attention in order to stay engaged in learning tasks. Three children enrolled in a half-day integrated preschool who were having difficulty staying engaged with group or independent learning activities participated in the study. The effects on engagement time of equal amounts of teacher attention, given at a rapid pace or at a slow pace, were compared. Rapid attention produced higher engagement time than slow attention or no attention for all dtree children. The results suggest that rapid-paced teacher attention may be effective in helping young children stay engaged in activities. The results are discussed in terms of basic research on behavioral momentum, which describes the effects of reinforcement rate on task persistence.

Behavioral contrast in pigeons and rats: A comparative analysis

The effects of reinforcement rate on behavioral contrast were examined in pigeons and rats. Each species was exposed to a series of 12 multiple variable-interval schedules, divided into four 3-schedule series. Each series consisted of a standard contrast manipulation, and baseline schedules provided a different rate of reinforcement in each of the series. The functions relating reinforcement rate to the magnitude of contrast were different across species. Rats showed a U-shaped function, with reliable contrast occurring only at high reinforcement rates. Pigeons showed an inverted U-shaped function, with contrast occurring on all schedules except the schedule providing the lowest rate of reinforcement. Pigeons discriminated between schedule components better than rats did, although differences in discrimination were probably not responsible for the differences in contrast. The results suggest that behavioral contrast in rats may be a different phenomenon from behavioral contrast in pigeons. The results cannot be explained by current theories, which view contrast as the product of a single general process.

EFFECTS OF REINFORCEMENT RATE AND REINFORCER MAGNITUDE ON CHOICE BEHAVIOR OF HUMANS1

Two experiments with human subjects investigated the effects of rate of reinforcement and reinforcer magnitude upon choice. In Experiment 1, each of five subjects responded on four concurrent variable-interval schedules. In contrast to previous studies using non-human organisms, relative response rate did not closely match relative rate of reinforcement. Discrepancies ranged from 0.03 to 0.43 (mean equal to 0.19). Similar discrepancies were found between relative amount of time spent responding on each schedule and the corresponding relative rates of reinforcement. In Experiment 2, in which reinforcer magnitude was varied for each of five subjects, similar discrepancies ranging from 0.05 to 0.50 (mean equal to 0.21), were found between relative response rate and relative proportion of reinforcers received. In both experiments, changeover rates were lower on the long-interval concurrent schedules than on the short-interval ones. The results suggest that simple application of previous generalizations regarding the effects of reinforcement rate and reinforcer magnitude on choice for variable-interval schedules does not accurately describe human behavior in a simple laboratory situation.