Lewis A. Bizo

The failure of Weber's law in time perception and production

Webers law--constancy of the coefficient of variation--is an apparently ubiquitous feature of time perception, and forms the foundation of several theories of timing. We sought evidence for Webers law in temporal production and categorization experiments. The production task required pigeons to switch between keys within a specified temporal window. The categorization task required them to classify a stimulus duration as either short or long. Weber fractions did not descend to a horizontal asymptote, but were U-shaped: they decreased as a function of target duration, and increased again at intermediate and long durations. This pattern conforms neither to Webers law, nor to its generalized form (Getty, D.J., 1975. Discrimination of short temporal intervals: a comparison of two models. Percept. Psychophys. 18, 1-8). A model of counter failure accommodated the U-shaped pattern.

The educational impact of team‐skills training: Preparing students to work in groups

BACKGROUND Despite a vast literature on collaborative learning (CL), there is little research on preparing students to work collaboratively. AIMS This two-phase evaluation investigated whether team-skills training could enhance the performance of collaborative groups through the introduction of a team development programme to a group-based undergraduate key-skills unit. SAMPLE Phase 1 compared two consecutive cohorts of second-year students, Cohort 1 (N = 94) who received no preparation, and Cohort 2 (N = 113) who received team-skills training. Phase 2 added Cohort 3 (N = 88), who also received team-skills training, to extend the analysis. METHOD In Phase 1, students in both Cohorts 1 and 2 worked on a series of curriculum based key-skill tasks across two semesters. Students worked in one group in Semester 1 and were then formed into new groups for Semester 2. Effects of the training were measured by student group marks and key-skill ratings. RESULTS Marks and key-skill ratings were significantly higher for the trained cohort in Semester 1 (p < .01). However, in Semester 2 performance reduced for the trained cohort in comparison to Semester 1. To explore this further, Phase 2 of the study evaluated Cohort 3, where after training, collaborative groups remained intact throughout the academic year. Results for Cohort 3 showed no attenuation of performance effects in Semester 2. CONCLUSIONS Phase 1 results support the use of team-skills training to enhance CL group performance. The findings for Phase 2 suggest that these benefits may be lost if training groups are disrupted.

Chapter 3 Time's causes

Publisher Summary This chapter interprets Aristotles four causes, which he called material, final, efficient, and formal as questions about what (description/ definition and substrate), why (function), how (mechanism), and like (analogs and models). These four causes organize the analysis of time and timing. Time is not a fourth dimension—although it may be measured on one. It is not itself a cause—even though effects unfold in time. Time was not discovered; it was invented. The conceptions of time that have been invented by physicists have been adopted by society at large, so that there is a good correlation between the physicists time— SI time—and that on our clocks—Big Ben Time. Both times are measured on cyclic interval scales. An animal is only said to be timing while it is involved in activities that in the past have been reinforced for improving temporal judgments.

Modeling the effects of fluoxetine on food-reinforced behavior

We propose a novel method to dissociate incentive motivation from memory and motor processes in instrumental performance. Components of a multiple fixed-ratio schedule of food reinforcement were adjusted to envelop the range of response requirements that maintained lever pressing by rats. We sought to manipulate motivation for food rewards with acute administrations of various doses (0–10 mg/kg) of fluoxetine, a 5-HT reuptake inhibitor that reduces food intake. A quantitative model of fixed-ratio performance derived from Killeens (1994) Mathematical Principles of Reinforcement (MPR) provided an adequate account of data from individual rats. Decreases in response rate resulting from fluoxetine were reflected in changes in estimates of activation, indexed by MPR parameter a; estimates of working memory capacity and lever pressing duration were not systematically affected. These results support the use of MPR parameter a to index incentive motivation using multiple fixed-ratio schedules that are adjusted to individual performance.

Understanding adherence to physiotherapy: findings from an experimental simulation and an observational clinical study

This article reports two studies assessing the influence of self-efficacy, outcome expectancies and aversive feedback on different aspects of adherence. Study 1 employed a computer simulation of physiotherapy to test experimentally the effects of aversive feedback (i.e., loud noise) experienced during simulated therapy on adherence behaviour in a student population. Study 2 examined whether similar effects of aversive feedback (i.e., pain) experienced during physiotherapy in a clinical setting would be observed in a longitudinal questionnaire study of predictors of adherence. In both studies, self-efficacy and outcome expectancies were assessed at baseline and after experience of the task (performing simulated or actual physiotherapy). Study 1 found that self-efficacy and outcome expectancies predicted persistence with simulated physiotherapy (i.e., completing the experimental session), whereas aversive feedback influenced adherence during sessions (i.e., correct response rate). Study 2 found that self-efficacy and outcome expectancies predicted persistence with actual physiotherapy (i.e., completing the prescribed number of sessions). Aversive feedback and outcome expectancies influenced adherence during sessions. We conclude that different factors predict different aspects of adherence behaviour. It is therefore important to measure both persistence over time and adherence during sessions, and to investigate the predictors of each dimension of adherence.

Temporal generalization and peak shift in humans

Three experiments investigated temporal generalization in humans. In Experiment 1, a peak shift effect was produced when participants were given intradimensional discrimination training. In Experiment 2, after training with a standard S1 and generalization testing with an asymmetrical series of durations, generalization gradients moved toward the prevailing adaptation level. In Experiment 3, generalization gradients showed a central tendency shift and moved away from the S1 and toward the mean of the test series (of 11 stimulus durations) after participants received training with S1 and S2 durations that in one condition were the 2nd and 4th and in another condition were the 4th and 2nd stimuli in the series, respectively. The results were inconsistent with an absolute account of peak shift but were consistent with an adaptation level account of peak shift.

Mediation of timing accuracy by operant behavior

We attempted to demonstrate that timing performance on a temporal discrimination would be enhanced if rats were required to fill a duration with behavior than when they were not required to respond. Six rats were trained to discriminate between a 3- and 9-s stimulus in a symbolic-matching-to-sample task. In two conditions, a tone was used to signal the sample, and in the other two conditions, a light was used to signal the sample. In two conditions, the rats were required to respond on a lever mounted on the rear wall of the experimental chamber before making their discriminative response to one of the two levers mounted on the front wall of the experimental chamber. In the other two conditions, the rear lever was not presented during sample presentation, and no response was required. Consistent with our predictions, timing performance was significantly better when a lever-response was required during sample presentation than when no response was required.

Human variable ratio performance

Abstract The generality of the mathematical principles of reinforcement (MPR) was tested with humans. In Experiment 1A, participants’ mouse clicks were reinforced according to a series of variable-ratio (VR) values. In one condition, a situated task was used (searching for treasure on a map presented via a PC monitor); in the other, abstract version of the task, participants clicked on a white screen. Under the “map” condition, response rates increased with increasing ratio value before decreasing with further ratio increases; under the “no-map” condition, response rates decreased linearly from a peak at the smallest ratio. In Experiment 1B, the pattern of responding was confirmed under the “map” conditions using a different set of ratio values. In Experiment 2, reinforcer magnitude was manipulated using the “map” context. Response rates did not differ significantly when large rather than small cash reinforcers were delivered according to a VR 30 but were significantly higher when large rather than small cash reinforcers were delivered according to a VR 120. Together these experiments offer qualified support for extending MPR to the behavior of human participants.

Domestic hen chicks’ conditioned place preferences for sound

Food and sounds (white noise, a food call and the sound of other chicks) were used in an attempt to establish conditioned place preferences with domestic hen chicks. Thirty-two chicks were randomly allocated to one of the 4 groups, and exposed to a 3-compartment apparatus to establish a baseline of their movements across 4 15-min sessions. They were then confined to one compartment and provided with free access to food or exposed to one sound for 15 min and then they were confined to the alternate compartment with no food or sound for 15 min. This process was repeated 3 times. Post-conditioning test sessions showed a conditioned place preference towards the area associated with food and away from the area associated with white noise. After conditioning, chicks showed no preference for spending time in the side associated with the food call or the sounds of other chicks; however, they entered a compartment first more often when it was associated with the food call and less often when it was associated with chick-sounds. Overall, these results showed that it was possible to use the conditioned place preference procedure to assess the effects of sounds and that the procedure has potential use for assessing other environmental stimuli.

Use of an ESP Cover Story Facilitates Reinforcement without Awareness.

Participants were exposed to 3 conditions in a between-groups design. Participants were told the experiment was about extrasensory perception and were asked to select the word from a pair of words that they thought the experimenter was thinking about. In 1 condition selections of the word with a double letter were reinforced with positive verbal feedback, and in another condition selections of nondouble letters were reinforced. The word selections of a control group were reinforced according to a random and predetermined order. By the end of the experimental session, participants who were reinforced for selecting a particular type of word, double letter or nondouble letter, selected that word significantly more than the alternative that was not associated with reinforcement and those participants in the control group selected the double-letter and nondouble-Ietter words equally often. In a postexperimental questionnaire none of the participants reported an awareness of the contingency. The present experiment replicates and extends previous work and confirms that participants’ behavior can be modified by reinforcement without the participants’ conscious awareness of the contingency.