Typical delay determines waiting time on periodic-food schedules: Static and dynamic tests

Pigeons and other animals soon learn to wait (pause) after food delivery on periodic-food schedules before resuming the food-rewarded response. Under most conditions the steady-state duration of the average waiting time, t, is a linear function of the typical interfood interval. We describe three experiments designed to explore the limits of this process. In all experiments, t was associated with one key color and the subsequent food delay, T, with another. In the first experiment, we compared the relation between t (waiting time) and T (food delay) under two conditions: when T was held constant, and when T was an inverse function of t. The pigeons could maximize the rate of food delivery under the first condition by setting t to a consistently short value; optimal behavior under the second condition required a linear relation with unit slope between t and T. Despite this difference in optimal policy, the pigeons in both cases showed the same linear relation, with slope less than one, between t and T. This result was confirmed in a second parametric experiment that added a third condition, in which T + t was held constant. Linear waiting appears to be an obligatory rule for pigeons. In a third experiment we arranged for a multiplicative relation between t and T (positive feedback), and produced either very short or very long waiting times as predicted by a quasi-dynamic model in which waiting time is strongly determined by the just-preceding food delay.     

Functional classes and equivalence relations

Three adult subjects were taught a set of two-choice simultaneous discriminations, with three positive and three negative stimuli; all possible combinations of positive and negative stimuli yielded nine different pairs. The discriminations were repeatedly reversed and rereversed, the former positive stimuli becoming negative and the former negative stimuli becoming positive. With all subjects, a reversal of the contingencies for one pair of stimuli became sufficient to change their responses to all of the other pairs. The reversals had produced functional stimulus classes. Then, all subjects showed conditional discriminations emerging between members of a functional class; given a sample from one class and comparisons from both classes, they selected the comparison that was in the same class as the sample. Next, 2 of the subjects showed that the within-class conditional relations possessed the symmetric and transitive properties of equivalence relations; after having been taught to relate new stimuli to existing class members, the subjects then matched other class members to the new stimuli. Subsequent tests of two-choice discriminations showed that the conditional discriminations had transferred functional class membership to the new stimuli. The 3rd subject, who did not show equivalence relations among functional class members, was also found to have lost the within-class conditional relations after the equivalence tests.     

Identifying the psychopath: The relation of Cleckley's criteria to the interpersonal domain

The relationship between interpersonal behaviour variables has been shown to be defined by a circular ordering, or circumplex, within the framework of a two-dimensional space. It is proposed that Cleckley's criteria of psychopathy represent one axis of this system, hostility vs warmth. It is also proposed that these criteria alone are not sufficient to identify a homogeneous group of deviant persons. Observer ratings of the behaviour of institutionalized mentally-disordered offenders were obtained for Cleckley's criteria and for behavioural dimensions of impulsive aggression and sociability. Cleckley's criteria were found to describe a unitary dimension whose relationship to other variables was consistent with the circumplex model. Cluster analysis of the ratings identified two distinct groups of high scorers on Cleckey's criteria, who were also significantly differentiated by self-report personality variables. Only one of these groups showed the combination of lack of warmth or affection and lack of behavioural control which several investigators consider necessary to define psychopathy. Relationships among individual rating items and some of the personality variables closely approximated the expected circular ordering. Reference to this interpersonal circumplex appears to reconcile some of the differences in current conceptualizations of psychopathic personality.     

Neuroticism,life stress and concern about eating,body weight and apperance in a non-clinical population

Studies with clinical populations have shown a high level of neuroticism amongst those with an eating disorder. It is unclear however whether the elevated neuroticism is a function of the disorder, or if it is an aetiological factor in the disorder's development. The present survey of a non-clinical female population revealed that those high in neuroticism gave higher—but not abnormally high—scores on a measure of concern about eating. The high-N group also reported a significantly greater number of undesirable life events; a greater familiarity with ‘diet literature’; increased dieting; but no difference in body weight from those in the middle and lower ranges on the N scale. On the basis of these findings it is suggested that neuroticism is an aetiological factor in disordered eating, at least with secondary if not primary disorders. It is propesed that neuroticism is one mediating psychological factor in a triadic relationship between personal environment contingencies, socio-cultural pressures for thinness and psychological variables. Suggestions are made for future investigation of the role of neuroticism in eating disturbance, with note of potential therapeutic application of such knowledge.     

Lay knowledge of eyewitness behaviour: A British survey

One of the recent concerns in the study of eyewitness memory is how well lay knowledge, i.e. ‘common sense’, matches the findings of empirical research. A number of American and Canadian studies, some using questionnaire methodology, have found limitations in lay knowledge of eyewitness behaviour. Further studies have extended this general finding beyond the lay public–who are prospective jurors–to legal professionals such as lawyers and policemen. The present study utilized the Knowledge of Eyewitness Behaviour Questionnaire (KEBQ), an inventory used in previous studies, to replicate the North American studies with a British sample of students, including law students, and the general public. The results showed a great similarity between the North American and British samples' knowledge of eyewitness behaviour. A significant number of correct responses were made to eight of the 14 KEBQ items, with a significant number of incorrect responses to the remainder. It was also found that law students were no more knowledgeable than other subjects; that knowledge did not vary with age; and that previous experience as an eyewitness was not related to knowledge of eyewitness behaviour. In responding to some of the criticisms of questionnaire studies it is argued that the evidence is mounting in favour of the need for a recognized system to make jurors aware of the factors known to influence eyewitness testimony.     

A Commodore 64-based interface system for the operant laboratory

A system of interfaces for the Commodore 64 (C-64) microcomputer for use in the operant laboratory is described. This system frees the experimenter from limitations on the number of I/O lines available on the user port of the C-64 and offers the control of operant chambers for a low cost. Subroutines in machine code to control the interfaces, offering millisecond timing of external events, are presented. A sample BASIC program demonstrates how the subroutines are called from BASIC to run a simple discrimination experiment.     

New Directions for Performance Appraisal: Some Findings and Observations

The changing emphasis on the aims of performance appraisal systems is discussed, with particular reference to the notion of appraisal as a motivating mechanism. The contention of the Total Quality school that the traditional focus on the assessment function of appraisal is counterproductive is supported, and some data are presented illustrating the doubtful value and accuracy of appraisal ratings, both for evaluating staff and as validation criteria for personality measures. Some implications of recent organizational changes for the development role of performance appraisal are reviewed, with particular reference to upward feedback and competency-based appraisal. Finally, the emerging shape of a new approach to meeting the purposes formerly served by appraisal systems is described.