Differential reinforcement and resistance to change of divided-attention performance

Behavioral momentum theory provides a framework for understanding how conditions of reinforcement influence instrumental response strength under conditions of disruption (i.e., resistance to change). The present experiment examined resistance to change of divided-attention performance when different overall probabilities of reinforcement were arranged across two components of a multiple schedule. Pigeons responded in a delayed-matching-to-sample procedure with compound samples (color + line orientation) and element comparisons (two colors or two line orientations). Reinforcement ratios of 1:9, 1:1, and 9:1 for accurate matches on the two types of comparison trials were examined across conditions using reinforcement probabilities (color/lines) of .9/.1, .5/.5, and .1/.9 in the rich component and .18/.02, .1/.1, and .02/.18 in the lean component. Relative accuracy with color and line comparisons was an orderly function of relative reinforcement, but this relation did not depend on the overall rate of reinforcement between components. The resistance to change of divided-attention performance was greater for both trial types in the rich component with presession feeding and extinction, but not with decreases in sample duration. These findings suggest promise for the applicability of quantitative models of operant behavior to divided-attention performance, but they highlight the need to further explore conditions impacting the resistance to change of attending.     

Human causality judgments and response rates on DRL and DRH schedules of reinforcement

The effect of various relationships between a response (an investment made in the context of a game) and an outcome (a return on the investment) on judgments of the causal effectiveness of the response was examined. In Experiment 1, response rates and causal judgments were higher for a differential-reinforcement-of-high-rate (DRH) schedule relative to a variable-ratio (VR) schedule with the same probability of outcome following a response. Response rates were also higher for a DRH than for a variable-interval schedule matched for reinforcement rate. In Experiment 2, response rates and causal judgments were lower for a differential-reinforcement-of-low-rate schedule relative to a VR schedule with the same probability of outcome following a response. These results corroborate the view that schedules are a determinant of both response rates and causal judgments, and that few current theories of causal judgment explicitly predict this pattern of results.     

The implications of low growth rates for higher education

The implications of low growth rates for higher education in the United States are discussed. Though some individual institutions may face financial difficulties, the problems associated with lower growth rates are likely to be organizational and educational rather than economic. Typical and possible responses to problems created by the transition from fast to slow growth are analysed, and the article ends with a discussion of important questions raised by the response to lower growth rates: the tendency towards more centralization has dangers for the diversity which is the best way of maintaining the flexibility needed to cope with an uncertain future.     

Simultaneous contrast in goldfish

Two groups of goldfish were trained to strike an illuminated target for food reward. The experimental group was reinforced with 10 worms for response to one color and with 1 worm for response to a different color. The control group was reinforced with 1 worm for response to each color. The experimental group gave clear evidence of discrimination of reward magnitude and also of simultaneous negative contrast. These results bear on the relation of the mechanisms of simultaneous and successive contrast.     

Analysis of autoshaping in goldfish

Stimulus-reinforcer and response-reinforcer control of target-striking in goldfish were studied in a series of discrete-trials experiments. Evidence of control by adventitious response-reinforcer contiguity was provided by the first experiment, which showed less response in animals given omission training than in yoked animals with the same stimulus-reinforcer experience. In the next three experiments, evidence of control by stimulus-reinforcer contiguity apart from response-reinforcer contiguity was sought in within-subjects comparisons of omission and extinction. Only the last of these experiments, in which the CS duration was short and the ITI long, showed greater response in omission. A subsidiary finding is that autoshaped goldfish respond very little, either to the CS target or to the feeder, when target and feeder are spatially discontiguous.     

Simultaneous contrast in the goldfish

In this, as in two prior experiments, goldfish trained with small reward for response to one color and large reward for response to another color performed less well for the small reward than control animals trained with small reward for response to both colors. The results obtained in the present experiment (with liquid food as reward) cannot be explained in terms of postingestive inhibition (evidence from the prior experiments withTubifex worms as reward being inconsistent on this point) or in terms of within-sessions decrement in drive. The results bear on the phyletic generality of simultaneous contrast and on the relation of simultaneous to successive contrast, a phenomenon that has thus far failed to appear in goldfish.     

Analysis of alternation patterning in goldfish

In Experiment 1, goldfish trained with alternation of reward (R) and nonreward (N) for responding to a single color gave clear evidence of patterning (more rapid responding on R than on N trials). In Experiment 2, patterning was found for each of two colors alternately rewarded and nonrewarded in the sequence blue R, yellow R, blue N, yellow N, …. Changes in performance with subsequent changes in the sequence of the two colors suggested that the patterning was based on carryover rather than on associative memory of R and N.     

Further experiments on probability learning in goldfish

The performance of goldfish in 70:30 and 50:50 visual and spatial problems was studied again under conditions like those employed in recent reversal experiments which provided the first unambiguous evidence of progressive improvement in goldfish. Random matching was found in the visual problems but not in the spatial problems, spatial choices proving rather insensitive to reinforcement ratio. The relation of random matching to the various other outcomes of such experiments is considered.     

Signal properties of reinforcement and reinforcement omission on a multiple fixed-ratio schedule

A series of experiments used food-deprived pigeons to examine several parameters of reinforcement omission in an attempt to control changes of keypeck response measures on a subsequent schedule. In Experiments 1 and 2, the pigeons were tested with a multiple fixed-ratio schedule on which reinforcement was occasionally omitted at the completion of the first component. The duration of the delay occurring in lieu of reinforcement was systematically varied. In Experiment 3, the stimulus that signaled the second component of the schedule was altered to appear either more or less similar to the stimulus that signaled the first component. Two principal results are reported: (1) Response latency decreased and, to a much lesser extent, terminal response rate increased as the delay occurring in lieu of reinforcement decreased; and (2) both latency decrease and response-rate increase were enhanced by a second component stimulus which was similar to the first. The results are evaluated in terms of Amsel’s frustration theory and an analysis by Staddon which suggests that reinforcement inhibits responding. The data appear to support Staddon’s argument that rate increases and latency decreases following reinforcement omission are largely a function of an attenuation of the inhibitory influence of reinforcement, an effect that is enhanced by stimulus generalization. Accordingly, it is proposed that an animal’s response to reinforcement omission is determined by a stimulus complex that minimally includes the omission event and component cues.     

Adjunctive behavior in multiple schedules of reinforcement

A recent theory of timing (Killeen & Fetterman, 1988) suggests that adjunctive behaviors may act as discriminative cues for the passage of time and that the rate of transition between those behaviors is affected by the rate of reinforcement within the experimental context. Is the rate of transition between behaviors correlated with the rate of reinforcement? What is the context in which rate of reinforcement is calibrated? If rate of transition is correlated with reinforcement frequency, does this correlation change with extended training? Four pigeons were trained on multiple fixed-time schedules of reinforcement, with one component always FT 15 sec, the other either FT 15 sec, FT 45 sec, or FT 5 sec. Behavior was coded into one of 12 categories. Response distributions in the constant component shifted when rate of reinforcement was varied in the other component and eventually shifted back toward their original location.     

Choice and percentage reinforcement in pigeons

Pigeons responded on a two-key concurrent chains choice procedure with the same level of percentage reinforcement on each key. During the initial links, a choice response on either key occasionally produced a conditioned reinforcer—which on one key was associated with a 15-sec, and on the other key with a 30-sec, interreinforcement interval—or an extinction stimulus. In Part 1, the initial links were equal. With successive decreases in the probability of a reinforcer, choice shifted from preference for the 15-sec terminal link toward indifference. In Part 2, the initial links were unequal and were arranged so that the shorter initial link preceded the 30-sec terminal link. At a high probability of a reinforcer, the pigeons again preferred the 15-sec terminal link. However, at a low probability, the pigeons reversed and preferred the alternate key. It was concluded that the conditioned reinforcers tended to become functionally equivalent at a low probability of a reinforcer, despite the nominally different interreinforcement intervals, with the result that choice was then modulated by the relative size of the initial links. The data are inconsistent with the view that choice and the strength of conditioned reinforcers are isomorphic with the reduction in delay to reward correlated with terminal link stimuli.     

Conjunctive schedules of reinforcement IV: Effects on the pattern of responding of changes in requirement at reinforcement

The effects of different schedule requirements at reinforcement on patterns of responding by pigeons were assessed under conjunctive schedules with comparable response-number requirements, Under one conjunctive schedule (conjunctive fixed-interval fixed-ratio schedule), a response was reinforced after a 6-min interval had elapsedand a specific minimum number of responses had been emitted, Under a second conjunctive schedule, a response was reinforced after the 6-min fixed interval and upon completion of a tandem schedule requirement (conjunctive fixed-interval tandem schedule), This schedule retained the same required minimum number of responses as the first conjunctive schedule, but responses were never reinforced according to a fixed-ratio schedule; the tandem schedule was comprised of a fixed-ratio and a small (.1 to 10.0 sec) fixed-interval schedule, Under the conjunctive fixed-interval fixed-ratio schedule, responding was characterized by an initial pause, an abrupt transition to a high response rate, and a second transition to a lower rate that prevailed or slightly increased up to reinforcement, Under the conjunctive fixed-interval tandem schedule, pauses were extended, response rates were lower, and the initial high rate of responding was generally absent, The above effects depended upon the size of the fixed interval of the tandem schedule, The distinct pattern of responding generated by conjunctive fixed-interval fixed-ratio schedules depends upon occasional reinforcement of fixed-ratio responding and not merely on the addition of a minimum number of required responses.     

The adjustment of goldfish to reduction in magnitude of reward in massed trials

For a group of goldfish trained in a runway under conditions of highly massed practice, reduction in magnitude of reward produced a gradual decline in performance to the level of a small-reward control group but no suggestion of negative successive contrast. These results are consistent with the suggestion that reward plays a somewhat different role in the learning of fish and rats. They also serve to extend the range of conditions under which the stimulus aftereffects of reward come to control the instrumental behavior of fish.     

多媒体教室扩声系统探讨

目前,多媒体教室已经成为高校教育教学的主要场所,扩声系统是多媒体教室设备的重要组成部分,但是在多媒体教室密集的教学楼或区域紧凑的教室群,现有技术的有线话筒已经不能满足应用需求。文章首先介绍了多媒体教室扩声系统的发展历程,包括有线(移频)话筒、红外线无线话筒等过渡性技术,其次,详细阐述了四种无线扩声技术的特点,并做了总结对比,通过技术比较表明,蓝牙无线话筒是目前多媒体教室无线话筒的技术发展趋势。     

关于进一步加强高职院校学风建设的探讨

学风建设关系到高职院校的兴衰,进一步加强学风建设是实现高职院校培养目标的根本保证,是学生成人成才的需要,是高职院校自身发展的内在要求。加强高职院校学风建设应从思想政治教育工作、师资队伍建设、政策制度和考风考纪等方面着手。     

Partial reinforcement and resistance to extinction in honeybees

Previous experiments have shown the partial reinforcement effect in honeybees under conditions which permit an interpretation in terms of sensory carryover. In the five experiments reported here, the effect was sought under conditions which would require an interpretation in terms of associative reinstatement. Since it is not feasible to train honeybees in widely spaced trials, several different interpolated-trials procedures were employed which had in common the feature that nonrewarded response to a stimulus never was followed by rewarded response to the same stimulus. Implications of the negative results for the interpretation of the overlearning-extinction effect and successive negative contrast in honeybees are considered.     

Intradimensional vs. extradimensional transfer in the discriminative learning of goldfish and pigeons

Evidence of better intradimensional than extradimensional transfer was sought in naive goldfish trained under free-operant single-stimulus conditions (Experiment I), sophisticated pigeons trained under free-operant single-stimulus conditions (Experiment II), sophisticated pigeons trained under discrete-trials choice conditions (Experiment III), and naive pigeons trained under discrete-trials choice conditions (Experiment IV). The results provide no support for attention theory.     

Discriminative stimuli that follow the absence of reinforcement are preferred by pigeons over those that follow reinforcement

Clement, Feltus, Kaiser, and Zentall (2000) found that when pigeons have to work to obtain a discriminative stimulus that is followed by reinforcement, they prefer a discriminative stimulus that requires greater effort over one that requires less effort. The authors suggested that such a preference results from the greater change in hedonic value that occurs between the more aversive event and the onset of the stimulus that signals reinforcement, a contrast effect. It was hypothesized that any stimulus that follows a relatively more aversive event would be preferred over a stimulus that follows a relatively less aversive event. In the present experiment, the authors tested the counterintuitive prediction of that theory, that pigeons should prefer a discriminative stimulus that follows the absence of reinforcement over a discriminative stimulus that follows reinforcement. Results supported the theory.     

Remembering: The role of extraneous reinforcement

In two experiments, pigeons' responding on an extraneous task was explicitly reinforced during delayed matching-to-sample trials. In Experiment 1, red or green sample stimuli were followed by retention intervals of 0.2, 1, 4, or 12 sec, during which pecks to a white center key were reinforced with 2.5-sec access to wheat according to extinction, variable-interval 30-sec, and variable-interval 15-sec schedules in different conditions. A proportion of .2, .5, .7, or .9 of subsequent red or green choice responses that matched the sample were reinforced with 3-sec access to wheat. The result was that increasing center key reinforcement, or reducing reinforcer probability, lowered overall accuracy. Initial discriminability fell, but with no change in the rate of forgetting. In Experiment 2, initial discriminability was affected by extraneous reinforcers that were contingent on center key pecking, but not by noncontingent reinforcers. A plausible conclusion is that initial discriminability decreases when reinforcers strengthen competing behaviors.