Depressed versus nondepressed young adult tobacco users: differences in coping style, weight concerns and exercise level.

Undergraduates age 18 to 24 years (n=656) completed questionnaires assessing tobacco use, depressive symptoms, coping responses, weight concerns, and exercise. The majority of participants were female (72%), White/non-Hispanic (95%), and in the 1st or 2nd year of college (80%). Current tobacco users (n=236) had a higher frequency of depression (40%) than never tobacco users (32%; p=.05). Tobacco users classified as depressed (Center for Epidemiological Studies Depression Scale [CES-D] score a 16) reported greater weight concerns and more frequent maladaptive coping in response to negative mood than tobacco users classified as nondepressed (CES-D score<16). Multivariate logistic regression analysis indicated that higher maladaptive coping and lower level of exercise were significantly associated with depression among tobacco users.     

Accumulator and random-walk models of psychophysical discrimination: a counter-evaluation

In a recent assessment of models of psychophysical discrimination, Heath criticises the accumulator model for its reliance on computer simulation and qualitative evidence, and contrasts it unfavourably with a modified random-walk model, which yields exact predictions, is susceptible to critical test, and is provided with simple parameter-estimation techniques. A counter-evaluation is presented, in which the approximations employed in the modified random-walk analysis are demonstrated to be seriously inaccurate, the resulting parameter estimates to be artefactually determined, and the proposed test not critical. It is pointed out that Heath's specific application of the model is not legitimate, his data treatment inappropriate, and his hypothesis concerning confidence inconsistent with experimental results. Evidence from adaptive performance changes is presented which shows that the necessary assumptions for quantitative analysis in terms of the modified random-walk model are not satisfied, and that the model can be reconciled with data at the qualitative level only by making it virtually indistinguishable from an accumulator process. A procedure for deriving exact predictions for an accumulator process is outlined.