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.     

Reliability and validity of the Coolidge Axis II Inventory: a new inventory for the assessment of personality disorders.

This group of studies describes the development of a 200 item, self-report, 4-point true-false inventory (Coolidge Axis II Inventory [CATI]) to assess personality disorders according to the criteria established in the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev. [DSM-III-R]; American Psychiatric Association, 1987). The 13 personality disorder scales of the CATI had a mean test-retest reliability of .90 and a median internal consistency (Cronbach's alpha) of .76. There was a 50% concordance rate with clinician's diagnosis for 24 personality disordered patients. The median concurrent validity (raw score sums) between the CATI and the Millon Clinical Multiaxial Inventory-II for the 13 personality disorder scales was .58. Preliminary studies also support the reliability and validity of Depression, Anxiety, and Brain Dysfunction scales.     

Job experiences over time, multiple roles, and women's mental health: a longitudinal study.

Are changes over time in the quality of a woman's job associated with changes in her psychological distress? Do family roles moderate these relationships? We addressed these questions using longitudinal data from a 2-year 3-wave study of a stratified random sample of 403 employed women who varied in occupation, race, partnership, and parental status. After estimating individual rates of change for each woman on each of the predictors and the outcome, we modeled the relationships between family role occupancy and change in job-role quality on the one hand, and change in psychological distress on the other. Among single women and women without children, as job-role quality declined, levels of psychological distress increased. Among partnered women and women with children, change in job-role quality was unrelated to change in psychological distress.     

Compartmentalization of positive and negative self-knowledge: keeping bad apples out of the bunch.

Three studies examined whether categorical organization of knowledge about the self explains variance in self-esteem and depression beyond that which is accounted for by sheer amount of positive or negative content. Compartmentalization is the tendency to organize positive and negative knowledge about the self into separate, uniformly valenced categories (self-aspects). As long as positive self-aspects are activated, access to negative information should be minimized. Compartmentalization was associated with high self-esteem and low depression scores for individuals whose positive self-aspects were important; when negative self-aspects were important, compartmentalization was correlated with low self-esteem and high depression scores. An analysis of self-aspect labels showed that individuals with compartmentalized organization define negative self-aspects in especially narrow terms. A possible relationship between compartmentalized organization and cognitive complexity is discussed.     

The effect of hypnotically elicited testimony on jurors' judgments of guilt and innocence.

Survey data from several countries indicate that many people believe that hypnosis may increase the accuracy of an eyewitness's memory; most experimental research, however, suggests that this belief is inaccurate. This study examined whether the belief could influence judgments of guilt and innocence in a simulated criminal trial. The results indicated that British undergraduates were more likely to find a male defendant guilty when told that the testimony against him had been elicited under hypnosis. Results concerning a nonhypnotic memory facilitation technique were found to be inconclusive, and the salience of hypnotically elicited testimony was ruled out as a contributory element.     

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.     

Choice with delayed and probabilistic reinforcers: effects of variability, time between trials, and conditioned reinforcers.

In a discrete-trials procedure with pigeons, a response on a green key led to a 4-s delay (during which green houselights were lit) and then a reinforcer might or might not be delivered. A response on a red key led to a delay of adjustable duration (during which red houselights were lit) and then a certain reinforcer. The delay was adjusted so as to estimate an indifference point--a duration for which the two alternatives were equally preferred. Once the green key was chosen, a subject had to continue to respond on the green key until a reinforcer was delivered. Each response on the green key, plus the 4-s delay that followed every response, was called one "link" of the green-key schedule. Subjects showed much greater preference for the green key when the number of links before reinforcement was variable (averaging four) than when it was fixed (always exactly four). These findings are consistent with the view that probabilistic reinforcers are analogous to reinforcers delivered after variable delays. When successive links were separated by 4-s or 8-s "interlink intervals" with white houselights, preference for the probabilistic alternative decreased somewhat for 2 subjects but was unaffected for the other 2 subjects. When the interlink intervals had the same green houselights that were present during the 4-s delays, preference for the green key decreased substantially for all subjects. These results provided mixed support for the view that preference for a probabilistic reinforcer is inversely related to the duration of conditioned reinforcers that precede the delivery of food.     

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.