Effects of Pointing Rate and Availability of Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation

While looking through laterally displacing prisms, subjects pointed 60 times straight ahead of their nose at a rate of one complete movement every 2 or 3 s, with visual feedback available early in the pointing movement or delayed until the end of the movement. Sagittal pointing was paced such that movement speed covaried with pointing rate. Aftereffect measures (obtained after every 10 pointing trials) showed that when the limb became visible early in a pointing movement, proprioceptive adaptation was greater than visual, but when visual feedback was delayed until the end of the movement, the reverse was true. This effect occurred only with the 3-s pointing rate, however. With the 2-s pointing rate, adaptation was predominately proprioceptive in nature, regardless of feedback availability. Independent of the availability of visual feedback, visual adaptation developed more quickly with 3-s pointing, whereas proprioceptive adaptation developed more rapidly with 2-s pointing. These results are discussed in terms of a model of perceptual-motor organization in which the direction of coordinative (guidance) linkage between eye-head (visual) and hand-head (proprioceptive) systems (and consequently the locus of discordance registration and adaptive recalibration) is determined jointly by pointing rate and feedback availability. An additional effect of pointing rate is to determine the rate of discordant inputs. Maximal adaptive recalibration occurs when the input (pointing) rate matches the time constant of the adaptive encoder in the guided system.     

Factors and Taxa, Traits and Types, Differences of Degree and Differences in Kind

ABSTRACT A taxon is a nonarbitrary class whose existence is conjectured as an empirical question, not a mere semantic convenience. Numerous taxa are known to exist in nature and society (chemical elements, biological species, organic diseases, geological strata, kinds of stars, elementary particles, races, cultures, Mendelizing mental deficiencies, major psychoses, vocations, ideologies, religions). What personality types, if any, occur in the nonpathological population remains to be researched by sophisticated methods, and cannot be settled by fiat or "dimensional" preference. The intuitive concept of taxonicity is to be explicated by a combination of formal-numerical and causal criteria. Taxometric methods should include consistency tests that provide Popperian risk of strong discorroboration. In social science, latent class methods are probably more useful than cluster algorithms.     

Predicting Zimbabwean women's ability to tell their partners to use condoms.

The effectiveness of AIDS education may depend on the development of models that predict and explain HIV prevention behavior. In this study, the aim was to test Fishbein and Ajzen's theory of reasoned action model in predicting women's capacity to tell their partner to use condoms. The basic theory pertains to the relationship of 1) attitude toward behavior and 2) the subjective norms to behavior; further refinements reflect factors such as 3) perceived behavioral control or self-efficacy, 4) and perceived barriers. A sample was drawn of 123 female first-year teacher trainees in Harare, Zimbabwe, in late 1990; a self-administered questionnaire was distributed and returned. 72% of the respondents were sexually experienced. The mean age of the entire sample was 24 years. The results of the multiple linear regression indicated that the model was able to predict were F(2,74)=32.81, p.0001. 47% of the variance was explained by this Fishbein model. Attitude toward behavior was significantly associated with the intention to tell one's partner to use condoms (beta = .60, p .05). Subjective norms were not significant (beta = .15, p .05). Perceived behavioral control and perceived barriers were also not significantly associated with the intention to tell one's partner to use condoms. A caveat was that the subjective norm was measured by only one item, and an improved conceptualization and measurement of this construct might have changed the relationship. The suggestion is that health educators should address women's underlying beliefs and attitudes about the benefits of telling their partners to use condoms. Future prospective studies will better delineate the relationship between attitude and behavior.     

Maximizing versus matching on concurrent variable-interval schedules

Maximization and matching predictions were examined for a time-based analogue of the concurrent variable-interval variable-ratio schedule. One alternative was a variable interval whose time base operated relatively independent of the schedule chosen, and the other was a discontinuous variable interval for which timing progressed only when selected. Pigeons switched between schedules by pecking a changeover key. The maximization hypothesis predicts that subjects will show a bias toward the discontinuous variable interval and undermatching; however the obtained results conformed closely to the predictions of the matching law. Finally, a quantitative comparison was made of the bias and sensitivity estimates obtained in published concurrent variable-interval variable-ratio analogue studies. Results indicated that only the ratio-based analogue of the concurrent variable interval variable ratio studied by Green, Rachlin, and Hanson (1983) produced significant bias toward the variable-ratio alternative and undermatching, as predicted by reinforcement maximization.     

Stimulus effects on concurrent performance in transition

Six experimentally naive pigeons were exposed to concurrent variable-interval variable-interval schedules in a three-key procedure in which food reinforcement followed pecks on the side keys and pecks on the center key served as changeover responses. In Phase 1, 3 birds were exposed to 20 combinations of five variable-interval values, with each variable-interval value consistently associated with a different color on the side keys. Another 3 pigeons were exposed to the same 20 conditions, but with a more standard procedure that used a nondifferential discriminative stimulus on the two side keys throughout all conditions. In Phase 2, the differential and nondifferential stimulus conditions were reversed for each pigeon. Each condition lasted for one 5-hr session and one subsequent 1-hr session. In the last 14 conditions of each phase, the presence of differential discriminative stimuli decreased the time necessary for differential responding to develop and increased the sensitivity of behavior to reinforcement distribution in the 1st hr of training; during the last hours of training in each condition, however, the effects of the differential discriminative stimuli could not be distinguished from the effects of reinforcement distribution per se. These results show the importance of studying transitions in behavior as well as final performance. They may also be relevant to discrepancies in the results of previous experiments that have used nonhuman and human subjects.     

Alcoholic subtypes and the MacAndrew Alcoholism Scale.

Forty-five alcoholics in treatment (29 males and 16 females) who reported substantial alcohol dependence but scored in the nonalcoholic range on the MacAndrew Alcoholism Scale (MAC) were matched with 45 alcoholics who reported a similar degree of alcohol dependence and obtained alcoholic-range scores on the MAC. Results reveal that high MAC alcoholics were characterized by gregariousness, social drinking, belligerence and aggression while drinking, and a high degree of alcohol-related legal problems. Low MAC alcoholics appeared to be a different or less distinctive type of alcoholic; although they were less outgoing and preferred not to drink with others, they experienced a wide range of serious alcohol-related consequences. Low MAC alcoholics were not more likely to have a history of nonsubstance use psychiatric diagnosis and treatment. Cloninger, Bohman, and Sigvardsson's (1981) alcoholic typology was related to MAC scores: There was a greater likelihood that high-MAC alcoholics were Type II and low MAC alcoholics Type I.     

Statistical power and the Rorschach: 1975-1991

The Rorschach Inkblot Test has been the source of long-standing controversies as to its nature and its psychometric properties. Consistent with behavioral science research in general, the concept of statistical power has been entirely ignored by Rorschach researchers. The concept of power is introduced and discussed, and a power survey of the Rorschach literature published between 1975 and 1991 in the Journal of Personality Assessment, Journal of Consulting and Clinical Psychology, Journal of Abnormal Psychology, Journal of Clinical Psychology, Journal of Personality, Psychological Bulletin, American Journal of Psychiatry, and Journal of Personality and Social Psychology was undertaken. Power was calculated for 2,300 statistical tests in 158 journal articles. Power to detect small, medium, and large effect sizes was .13, .56, and .85, respectively. Similar to the findings in other power surveys conducted on behavioral science research, we concluded that Rorschach research is underpowered to detect the differences under investigation. This undoubtedly contributes to the inconsistency of research findings which has been a source of controversy and criticism over the decades. It appears that research conducted according to the Comprehensive System for the Rorschach is more powerful. Recommendations are offered for improving power and strengthening the design sensitivity of Rorschach research, including increasing sample sizes, use of parametric statistics, reduction of error variance, more accurate reporting of findings, and editorial policies reflecting concern about the magnitude of relationships beyond an exclusive focus on levels of statistical significance.     

Hillel's maxim: Framework for psychological health

Mental health practitioners continually struggle to find a simple framework for describing the characteristics of the psychologically healthy individual. Hillel's often quoted saying provides relevant insight into the healthy personality and a convenient framework against which to examine psychological health.