Conditioning of a discriminative drug stimulus: Overshadowing and blocking like procedures

Interactions between a drug discriminative stimulus ( D , 17.5 mg/kg of pentobarbital vs. N , saline) and exteroceptive stimulus conditions (light vs. dark) were examined in a T-maze, shock-escape task using conditioning procedures pertaining to the phenomena of "overshadowing" and "blocking". From an operational point of view, in the "overshadowing" procedure the stimulus compound is introduced from the outset of the training, whereas in the "blocking" procedure the stimuli components are introduced sequentially. When the compound discriminations were established, dose-generalization tests with various doses of pentobarbital (range 5.6–17.5 mg/kg) as well as saline (1 ml/kg) were carried out under both elements (light and dark) of the exteroceptive stimulus dimension. Prior training with drug ( D vs. N ) neutralized the potential influence of the exteroceptive dimension (light vs. dark); conversely training with the exteroceptive stimuli prior to the drug training accentuated the control over behavior by the visual stimuli. Dose-generalization results intermediate to those described above were observed in the group trained to discriminate the stimulus compound ( D plus light vs. N plus dark) from the outset of training. It may therefore be concluded that exteroceptive stimuli can compete with interoceptive drug stimuli for associative strength in the procedure used. Thus, the formal similarities between drug discriminative stimuli and more conventionally studied exteroceptive, sensory signals are furthered by the data.     

Moral Responsibility and the Metaphysics of Free Will: Reply to van Inwagen

In The Philosophical Quarterly , 47 (1997), pp. 373–81, van Inwagen argues in a critical notice of my book The Metaphysics of Free Will that the impression that Frankfurt-type examples show that moral responsibility need not require alternative possibilities results from insufficient analytical precision. He suggests various precise principles which imply that moral responsibility requires alternative possibilities. In reply, I seek to defend the conclusion I have drawn from Frankfurt-type examples: moral responsibility need not require alternative possibilities. I contend that van Inwagen's principles — the principle of possible prevention and the no-matter-what principle — are invalid, and I suggest that their plausibility comes from thinking about a proper subset of the relevant cases.     

Body image and self-esteem in adolescent ballet dancers.

Body-image disturbances and low self-esteem have been implicated in the pathogenesis of eating disorders. This study investigated self-perception of body and personality among adolescent ballet dancers in a cross-sectional survey. Two questionnaires assessing "my body right now" and "my personality right now," using semantic differentials were completed by 90 ballet school students and 156 controls. Adolescent female dancers (ages 13 to 17 years) scored higher than age-matched controls and 11- to 12-yr. old peers on Undesirability and Sensitivity for personality and Unattractiveness for body. For both subscales of personality, differences were also found between male and female dancers; female ballet students scored higher. Within the control group a difference could be found only for Sensitivity on which girls scored higher than boys. Male dancers did not differ from controls except for a lower score on the Body mass measure. Adolescent female dancers showed a distinct answering profile for 7 of 16 semantic differentials in each questionnaire implicating less favorable body image and self-esteem. Interventions focused particularly on enhancing self-esteem may be useful in the prevention of psychopathology in adolescent ballet dancers.     

Statistical properties of the rWG(J) index of agreement

L. R. James, R. G. Demaree, and G. Wolf (1984) introduced rWG(J) to estimate interrater agreement for a group. This index is calculated by comparing an observed group variance with an expected random variance. As researchers have gained experience using this index, several questions have arisen. What are the consequences of replacing values beyond the unit interval by 0? What is the dependence of rWG(J) on the group size? The authors' simulations show that a positive bias is caused by the truncation, but for large population values of rWG(J) it is negligible. Also, in this case, the group size has no effect on the expected value of rWG(J). For inference on rWG(J), researchers can exploit the availability of computers to simulate data from the hypothesized distribution and then compare the simulation results for rWG(J) with the actual values. In addition, it is shown how the bootstrap method can be used for comparing the indices of 2 groups.     

Trends in attempted suicide in Denmark, 1976-1980

The object of the present study was to estimate proportions and changes in the incidence of suicide attempts in Denmark. Case sheets concerning all admissions in 1976-1979 (total 6,650) at the Department of Psychiatry, Odense University Hospital (the catchment area of which provides a representative sample of the Danish population), were examined with a view to establishing the reasons for admission. Rates of suicide attempts by age and sex in 1976-1979 were calculated, and estimated rates of the suicide attempts in 1980 added. Trend analysis showed an increase in the mean rates from 1976 to 1979 of 48%, followed by a decrease in 1980 of 13%. There were high increases among the adolescents, but the increase was above all due to the fact that more and more men attempted suicide; the study suggests as a new phenomenon more male than female suicide attempters. We stress the fact that incidences calculated on the basis of hospital admissions only underestimate the real proportions of self-destructive behavior.     

Initial results with bright light (phototherapy) in affective psychoses

The biological foundations of light-treatment and their relation to neurophysiological and biochemical mechanisms were discussed. We developed an apparatus for treatment and report of first experiences in affective psychosis. In addition to a decrease of depressivity and anxiety we found an unequivocal tendency to normalization of sleep-behaviour. The farther clinical and paraclinical investigations has to show the position of this method of treatment in the total conception of a biological therapy.