Win-shift and win-stay learning in the short-beaked echidna (<Emphasis Type="Italic">Tachyglossus aculeatus</Emphasis>)

Numerous previous investigators have explained species differences in spatial memory performance in terms of differences in foraging ecology. In three experiments we attempted to extend these findings by examining the extent to which the spatial memory performance of echidnas (or "spiny anteaters") can be understood in terms of the spatio-temporal distribution of their prey (ants and termites). This is a species and a foraging situation that have not been examined in this way before. Echidnas were better able to learn to avoid a previously rewarding location (to "win-shift") than to learn to return to a previously rewarding location (to "win-stay"), at short retention intervals, but were unable to learn either of these strategies at retention intervals of 90 min. The short retention interval results support the ecological hypothesis, but the long retention interval results do not. Electronic Publication     

The anatomy of loneliness

Loneliness is a potent but little understood risk factor for broad-based morbidity and mortality. We review five social neurobehavioral mechanisms that may account for this association. The evidence suggests that different mechanisms explain short-term and long-term effects, and that the long-term effects operate through multiple pathways. Implications for the design of interventions are discussed.     

Social integration and social support in a life crisis: Effects of macrosocial change in east Germany

This process evaluation study examined what variables moderate and mediate treatment effects on days in stable housing and client satisfaction for homeless mentally ill clients. In general, demographic characteristics did not moderate either outcome variable. Housing contacts, entitlement contacts, mental health contacts, and supportive services were significant mediators of the treatment effect on days in stable housing. Program contacts, mental health contacts, and supportive services were significant mediators of client satisfaction. The authors thank the National Institute of Mental Health for their financial support (MH43248, MH42357) for this project, Dorothy Gano for word processing and editorial assistance, and Gitry Heydebrand, Melissa Dannelet, Betty Tempelhoff, Ruth Smith, and Laeeq Ahmad for assisting in the interviews of clients. We are also appreciative of the cooperation given to us by the staffs of Malcolm Bliss Mental Health Center, St. Patrick's Center, the Community Advocacy and Support Alliance Program, and the St. Louisemergency shelters. Finally, we thank all of the participants in this study; we hope that their homelessness has now ended. (The conclusions presented in this paper are the sole responsibility of the authors and do not necessarily reflect official National Institute for Mental Health policy.)     

Long-term associative learning predicts verbal short-term memory performance

Studies using tests such as digit span and nonword repetition have implicated short-term memory across a range of developmental domains. Such tests ostensibly assess specialized processes for the short-term manipulation and maintenance of information that are often argued to enable long-term learning. However, there is considerable evidence for an influence of long-term linguistic learning on performance in short-term memory tasks that brings into question the role of a specialized short-term memory system separate from long-term knowledge. Using natural language corpora, we show experimentally and computationally that performance on three widely used measures of short-term memory (digit span, nonword repetition, and sentence recall) can be predicted from simple associative learning operating on the linguistic environment to which a typical child may have been exposed. The findings support the broad view that short-term verbal memory performance reflects the application of long-term language knowledge to the experimental setting.     

A critique of Dennett

This essay is intended to be a systematic exposition and critique of Daniel Dennett's general views. It is divided into three main sections. In section 1 we raise the question of the nature of a plausible scientific psychology, and suggest that the question of whether folk psychology will serve as an adequate scientific psychology is of special relevance in a discussion of Dennett. We then characterize folk psychology briefly. We suggest that Dennett's views have undergone at least one major change, and proceed to discuss both his earlier and his later views.In section 2 we suggest that Dennett is correctly perceived as an instrumentalist in his earlier works. We think that Dennett later abandons this position because of general worries about instrumentalism and, more importantly, because Dennett became convinced that an instrumentalist conception of folk psychology will not enable us to vindicate the notions of personhood, moral agency, and responsibility. This left Dennett with a dilemma. On the one hand, he does not think that beliefs, etc., will turn out to be genuine scientific posits. On the other hand, he thinks that moral agency would be impossible if we could not treat beliefs, etc. as causally efficacious in some suitable sense.In section 3 we discuss Dennett's resolution of this dilemma. The key to his current view, we suggest, is the illata-abstracta distinction. Dennett holds that both illata and abstracta are real and have causal powers, even though only illata are genuine scientific posits. He suggests that beliefs etc. are abstracta, and are the subject matter of what he calls intentional system theory. The subject matter of another theory, what Dennett calls subpersonal cognitive psychology, are illata, which are subpersonal intentional states. The important point is that this distinction lets Dennett have it both ways: (i) Since beliefs are mere abstracta, we need not commit ourselves to the thesis that beliefs will turn out to be posits of an adequate scientific psychology. (ii) Since beliefs have causal power, we are assured of moral and rational agency. We shall argue that Dennett's current view is untenable. If we are right in our arguments, then Dennett's program to produce a scientifically plausible psychology, one that will turn out to vindicate folk psychology (in some suitable sense), is a failure. It fails in the following important ways: (i) What Dennett sketches — intentional system theory cum subpersonal cognitive psychology — is not a plausible scientific psychology. (ii) As a consequence, Dennett also fails to provide a satisfactory foundation for moral and rational agency.     

Equating the brightness of brief visual stimuli of unequal durations

The brightness of brief displays whose durations do not exceed a critical period of integration is known to covary with stimulus duration (Bloch’s law). There are cases in which the interdependence of duration and brightness introduces an unwanted confounding that must be avoided. Three methods for equating the brightness of brief stimuli displayed under computer control are described and evaluated, and an example of the outcome obtained with the most efficient procedure is reported.     

The Effect of Mental Practice and Goal Setting as a Transfer of Training Intervention on Supervisors' Self-efficacy and Communication Skills: An Exploratory Study

Mental practice, where goal setting was either implicit or explicit, was investigated in a pulp and paper mill as a post-training intervention with regard to self-efficacy and the transfer of newly taught communication skills to the work setting. Six months after the supervisors had been trained, a 2×2 ANCOVA showed that self-efficacy was significantly higher for the supervisors who engaged in either mental practice or in mental practice combined with goal setting than for those in the goal setting only or control conditions. Self-efficacy correlated significantly with goal commitment and communication skills on the job. Hierarchical regression analysis indicated that the supervisor's imagery skills moderated the effect of mental practice on self-efficacy. Both the supervisors in the mental practice and in the goal setting and mental practice conditions were observed by peers to have improved their communication behaviour on the job. No change in communication behaviour was observed on the part of supervisors who set goals but did not engage in mental practice or were assigned to the control group.