This meta-analysis tested the Dodo bird conjecture, which states that when psychotherapies intended to be therapeutic are compared, the true differences among all such treatments are 0. Based on comparisons between treatments culled from 6 journals, it was found that the effect sizes were homogeneously distributed about 0, as was expected under the Dodo bird conjecture, and that under the most liberal assumptions, the upper bound of the true effect was about .20. Moreover, the effect sizes (a) were not related positively to publication date, indicating that improving research methods were not detecting effects, and (b) were not related to the similarity of the treatments, indicating that more dissimilar treatments did not produce larger effects, as would be expected if the Dodo bird conjecture was false. The evidence from these analyses supports the conjecture that the efficacy of bona fide treatments are roughly equivalent.

Subjects viewed unambiguous versions of both stationary and rotating Necker cube illusions for varying durations prior to the presentation of the standard ambiguous figure. In each case, the subjects were more likely to report the ambiguous figure to be (1) in the same configuration as that ofthe preceding prime following briefpreexposure periods and (2) in the opposite configuration from that of the preceding prime following long preexposure periods. In addition, the number of reversals of the figure during the test period was also strongly related to the duration of the preexposure period, with progressively fewer reversals reported following longer preexposure periods. The results are interpreted as revealing the concurrent roles of "set" effects in the brief preexposure conditions and neural fatigue effects in the long preexposure conditions. Furthermore, the ability of the proposed two-process model to integrate the myriad of empirical effects in the reversible-figure literature is emphasized.

Psychological consequences of exercise deprivation in habitual exercisers. The purpose of this investigation was to evaluate the influence of 3 d of exercise deprivation on selected psychological variables. Ten volunteers (4 female and 6 male) who regularly exercised 6-7 d.wk-1 for at least 45 min at a time participated in a 5-d study. Participants completed their regular workout on the first day of the study, refrained from physical activity for the next 3 d, and then resumed their regular exercise on the 5th d of the study. Participants reported to the lab on Monday following their regular workout and completed a series of questionnaires, and these same questionnaires were completed at the same time of day on the next 4 d. The dependent variables consisted of state and trait anxiety (STAI), and tension, depression, anger, vigor, fatigue, confusion, and overall mood (POMS). Increases in total mood disturbance, state anxiety, tension, depression, and confusion across days were significant (P < 0.05), and vigor decreased. The pattern of increasing mood disturbance with exercise deprivation was followed by mood improvement to baseline levels when exercise was resumed. We concluded that a brief period of exercise deprivation in habitual exercisers results in mood disturbance within 24-48 h.

On the basis of a meta-analysis of comparisons of bona fide psychotherapies, B. E. Wampold et al. (1997) concluded that the available evidence supported the notion that all psychotherapies are nearly equal in terms of efficacy. K. I. Howard, M. S. Krause, S. M. Saunders, and S. M. Kopta (1997) and P. Crits-Christoph (1997) raised 4 general issues with this conclusion: (a) counterexamples, (b) untested alternative hypotheses, (c) methodological problems, and (d) adequacy of randomized clinical trials. Each of these issues is discussed, and it is asserted that empirically there is no basis to alter the conclusions reached in B. E. Wampold et al.'s (1997) meta-analysis.

The authors investigated the preferences of Social (S) and Investigative (I) people for performing S and I tasks with either S or I people or alone. Participants, 38 upper division undergraduates in Social majors and 15 upper division undergraduates in Investigative majors, were administered a paired-comparison inventory in which the stimuli to be compared were task (S or I) and people (S, I, or alone) combinations. As expected, S participants preferred to work with S people, particularly on S tasks, although they preferred (slightly) to perform an I task with S people rather than an S task with I people. I participants most preferred to perform I tasks with I people and least preferred to perform an I task with S people, confirming the conjecture that I people avoid S environments that require emotional interactions, in spite of the tasks that might be performed in the environment.Editor's Note. Lenore Harmon served as the action editor for this article.-BEW