TEMPORAL CONTROL ON INTERVAL SCHEDULES: WHAT DETERMINES THE POSTREINFORCEMENT PAUSE?

On fixed-interval or response-initiated delay schedules of reinforcement, the average pause following food presentation is proportional to the interfood interval. Moreover, when a number of intervals of different durations occur in a programmed cyclic series, postreinforcement pauses track the changes in interval value. What controls the duration of postreinforcement pauses under these conditions? Staddon, Wynne, and Higa (1991), in their linear waiting model, propose control by the preceding interfood interval. Another possibility is that delay to reinforcement, signaled by a key peck and/or stimulus change, determines the subsequent pause. The experiments reported here examined the role of these two possible time markers by studying the performance of pigeons under a chained cyclic fixed-interval procedure. The data support the linear waiting model, but suggest that more than the immediately preceding interfood interval plays a role in temporal control.     

Frege on the psychological significance of definitions

Conclusion In contemporary work, the distinction between the proposition expressed by a sentence and its psychological significance is usually motivated by a familiar kind of counterfactual argument; and the discussion of these issues usually centers around the role of external factors in determining the meaning of our words. My primary goal in this paper has been to show that a similar, though not identical, distinction between two aspects of meaning can be developed entirely on the basis of considerations internal to language users — their cognitive limitations. To make this point, I have focused on symbols introduced through stipulative definitions. In a language containing such symbols, certain expressions and their definitional reductions will seem to differ in psychological significance for creatures with limited intellects, and so in any aspect of meaning that is supposed to correlate with psychological significance; but it seems also that there is some important aspect of meaning that they share.I have argued that a distinction in meaning like this — between sense and psychological significance — should be drawn even in the kind of languages of most concern to Frege, and that his failure to do so led to tensions in his thought. Of course, this observation only touches on the many issues involved in interpreting Frege's theory of definition more generally. I have not tried to describe here, for example, the ways in which the weak interpretation of fruitfulness might interact with the more robust interpretation mentioned earlier; I have only mentioned Frege's view on explicative definitions and the paradox of analysis, and failed even to mention either his treatment of contextual definition, or his peculiar objections to conditional definitions. I do want to emphasize, however, that the distinction drawn here is not simply a matter of Frege scholarship, but that it has some contemporary relevance as well. As we have seen, Frege's semantic goals often coincide with our own; and a number of contemporary writers are explicitly concerned, like Frege, to construct a semantic theory that is able to account for differences in meaning among logically equivalent expressions. Any such theorist should recognize a distinction like that drawn here between sense and psychological significance, and should avoid subjecting an account of one notion to constraints appropriate only for the other.     

An alternating least squares method for the weighted approximation of a symmetric matrix

Bailey and Gower examined the least squares approximationC to a symmetric matrixB, when the squared discrepancies for diagonal elements receive specific nonunit weights. They focussed on mathematical properties of the optimalC, in constrained and unconstrained cases, rather than on how to obtainC for any givenB. In the present paper a computational solution is given for the case whereC is constrained to be positive semidefinite and of a fixed rankr or less. The solution is based on weakly constrained linear regression analysis.The authors are obliged to John C. Gower for stimulating this research.     

Schedule-induced defecation by rats during ratio and interval schedules of food reinforcement.

Lever pressing in rats was maintained by continuous and intermittent schedules of food while defecation was monitored. In Experiment 1, reinforcement densities were matched across variable-ratio and variable-interval schedules for three pairs of rats. Defecation occurred in all 3 rats on the variable-ratio schedule and in all 3 rats on the yoked variable-interval schedule. In Experiment 2, fixed-ratio and fixed-interval schedules with similar reinforcement densities maintained lever pressing. Defecation occurred in 3 of 4 rats on the fixed-ratio schedule and in 4 of 4 rats on the fixed-interval schedule. Almost no defecation occurred during continuous reinforcement in either experiment. These results demonstrate that defecation may occur during both ratio and interval schedules and that the inter-reinforcement interval is more important than the behavioral requirements of the schedule in generating schedule-induced defecation.     

A generalized family of coefficients of relational agreement for numerical scales

A family of coefficients of relational agreement for numerical scales is proposed. The theory is a generalization to multiple judges of the Zegers and ten Berge theory of association coefficients for two variables and is based on the premise that the choice of a coefficient depends on the scale type of the variables, defined by the class of admissible transformations. Coefficients of relational agreement that denote agreement with respect to empirically meaningful relationships are derived for absolute, ratio, interval, and additive scales. The proposed theory is compared to intraclass correlation, and it is shown that the coefficient of additivity is identical to one measure of intraclass correlation.The author thanks the Editor and anonymous reviewers for helpful suggestions.     

Health behavior, knowledge and attitudes among Swedish university students

A range of health behaviors was related to beliefs concerning health practices and health knowledge. A questionnaire dealing with health-related practices, health beliefs and knowledge of health risk factors was answered by 166 male and 179 female students aged 18–30 years at Stockholm University. Female students reported engaging in better health behavior than males. Beliefs about the importance of health behaviors were closely related to their frequency of occurrence. There was only a weak relationship between health behaviors and knowledge of specific health matters. It is concluded that health attitudes rather than health knowledge determine health behavior.     

An Evaluation of the Effectiveness of Self-Efficacy as a Predictor of Trainees' Counselling Skills Performance

The value of self-efficacy as a predictor of counselling skills performance in a graduate counselling class was evaluated with 31 trainee counsellors. Three measurements of self-efficacy were taken: before, midway through, and at the end of a microcounselling skills training programme which was taught over six weekly three-hour sessions. Although there was a wide distribution of self-efficacy reports, none of the estimates of grade were significantly positively associated with counselling skills. Implications for counsellor educators are discussed.     

Psychological well-being and homemaker vs. retiree identity among older women

Social roles have been a central focus in both sociological and developmental theories of adjustment in late life. Research on roles and well-being, however, has focused on earlier adulthood or on comparisons of tenuous roles (such as retiree) with institutional roles (such as employee), especially among men. The few studies comparing older women in the tenuous roles of homemaker and retiree all compare single-role women, and show contradictory results. One possibility is that multiple role identities are linked to greater well-being in older women, as they are among younger women. In this paper the life satisfaction, depression, and self-esteem of older women who consider themselves retired only, homemakers only, or both are compared. The sample includes 864 Black (N=242) and White (N=622) women ages 60 and over from a 1986 national survey. Retired women and homemakers did not differ in well-being; women who called themselves both had higher self-esteem and lower depression than single-role women. In analyses exploring what tenuous role content (daily activities) might explain group differences in well-being, do-it-yourself activities and volunteer activities were significant. Age, education, health, and marital status were also important factors. Recommendations include adopting a multiple role perspective with older women and encouraging their participation in instrumental, informal role activities to maximize well-being.Northwestern University     

The stability of individual differences in gender typing: Implications for understanding gender segregation

The stability of individual differences has important implications for understanding the origins of gender-typed behaviors. For example, if some children have a stronger preference for same-sex playmates (gender segregation) than do others, then exploring characteristics that may differentiate these children from their peers (e.g., preference for gender-typed toys or teacher proximity) should prove fruitful. Otherwise, research might be focused more appropriately on group-level processes or situational factors rather than individual differences. In the current study, 57 2 1/2- to 3-year-olds from middle-class Canadian homes were observed repeatedly during free play at their preschools. Four aspects of gender typing (gender segregation, use of masculine and feminine gender-typed toys, teacher proximity) were measured so that the stability of individual differences and relations among the measures could be assessed. Stable individual differences were found for all four measures among boys, and for two of the measures (feminine toy play, teacher proximity) among girls. In addition, boys who played most frequently with masculine toys rarely were observed in proximity to the teacher. However, there was no relation between gender segregation and the other indices of gender typing.