Impaired motor-skill learning, slowed reaction time, and elevated cerebrospinal-fluid quinolinic acid in a subgroup of HIV-infected individuals.

29 Ss infected with HIV were evaluated on a motor-skill learning task known to be sensitive to basal ganglia lesions. Reaction time (RT) and CSF concentrations of an endogenous neurotoxin, quinolinic acid, were also measured. In comparison with 15 HIV– controls, 7 of the HIV+ Ss (24%) showed minimal motor-skill learning. These HIV+ Ss were also slower and had higher concentrations of CSF quinolinic acid than did HIV+ Ss who performed normally on the motor skill task. Motor-skill learning and RT were significantly correlated with CSF quinolinic acid but not with peripheral markers of immune system status (e.g., CD4 cell counts). These findings suggest that the basal ganglia may be a prominent locus of pathology in a subgroup of HIV-infected individuals and that quinolinic acid may play an important role in the pathogenesis of HIV-related neuronal dysfunction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Caregiving in virgin mice (Mus musculus): Effects of biparental care and exposure to a second litter during preweaning development.

Examined the effects of early family unit conditions on later parenting behavior in laboratory mice (Mus musculus) and challenged previous studies that claim to show enhancing effects of biparental care on offspring parental responsiveness by raising mice with a male parent either present (MPP) or absent (MPA) during preweaning development. The results of these studies are confounded because MPP mice also have a 2nd litter present (SLP) and MPA mice do not (SLA). Thus, the findings may have been due to the presence of a 2nd litter and not to the presence of the male parent. In this experiment, the author shows that when offspring raised in different family units are tested as virgins with stimulus pups, more SLP mice are parental than SLA mice, and fewer SLP mice bite newborn pups than do SLA mice. Thus, results of previous studies are due to 2nd litter exposure and not biparental care. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

“Everyone knows their Miranda rights”: Implicit assumptions and countervailing evidence.

In its landmark decision in Miranda v. Arizona (1966), the Supreme Court of the United States buttressed the Constitutional privilege against self-incrimination by requiring as a procedural safeguard that various aspects of this privilege be clearly communicated to custodial suspects. Members of the public often believe that their continually media-fueled familiarity with Miranda warnings results in an adequate understanding of Miranda rights—a frequently erroneous assumption that may diminish counsel's motivation to investigate Miranda waivers and may influence court rulings on the validity of such waivers. The current investigation examined Miranda rights misconceptions held by two groups of pretrial defendants: those arrested more recently (i.e., less than 2 weeks ago) and those arrested less recently (i.e., 4 weeks ago or more). The misconceptions of these groups were then contrasted with those of undergraduate students representing a more educated and comparatively unstressed segment of American society. Results revealed a host of widely-held misconceptions, including a fundamental misunderstanding of the function of the “right to remain silent” as a legal protection. Moreover, many misconceptions appeared unrelated to intelligence, education, or prior contacts with the criminal justice system. The implications of these findings are discussed with respect to the validity of Miranda waivers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The backpropagation algorithm on grid and hypercube architectures

In this paper, we first describe a model for mapping the backpropagation artificial neural net learning algorithm onto a massively parallel computer architecture with a 2D-grid communications network. We then show how this model can be sped up by hypercube inter-processor connections that provide logarithmic time segmented parallel prefix operations. This approach can serve as a general model for implementing algorithms for layered neural nets on any massively parallel computers that have 2D-grid or hypercube communication networks.

We have implemented this model on the Connection Machine CM-2 — a general purpose, massively parallel computer with a hypercube topology. Initial tests show that this implementation offers about 180 million interconnections per second (IPS) for feed-forward computation and 40 million weight updates per second (WUPS) for learning. We use our model to evaluate this implementation: what machine-specific features have helped improve the performance and where further improvements can be made.     

The social cognitive development of abused children.

Previous research on the impact of parental abuse on child development has typically been skewed to the more seriously injured or most socially disadvantaged families. The few studies attending to psychological consequences of abuse have further been limited by a failure to control for potentially confounding intellectual or demographic factors and have been too general in approach to provide effective guidelines for differential diagnosis, treatment, or theory building. The present study compared the social cognitive styles of 17 abused children and 16 controls (mean age 7 yrs 6 mo) and found differences in perceived locus of control of social events and social role comprehensions. Similar trends emerged in perspective-taking skills and social sensitivity. These alternative social cognitions could not be attributed to IQ or class disparities between groups. Implications for treatment and as a theoretical model for understanding the intergenerational nature of abuse are discussed. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strategic self-presentation in supervision.

A counselor trainee with a defensive self-presentational style is one who takes credit for the client's improvement or blames the client for deterioration. Conversely, a trainee with a counterdefensive style attributes improvement to the client or accepts personal responsibility for deterioration. 80 experienced (1–25 yrs) supervisors heard a tape of a simulated supervisory session in which a female trainee summarized her ongoing treatment of a moderately depressed client. Ss heard the trainee (a) describe how, recently, the client's depression had either lifted (improvement condition) or worsened (deterioration condition); and (b) attribute this change either to her own efforts or to the client. Ss then completed several measures, including an abbreviated version of the Counselor Rating Form. The counterdefensive trainee was judged to be somewhat more socially skilled than the defensive trainee, but the defensive trainee was rated as significantly more self-confident. Regardless of the trainee's explanation, however, when the client's depression lifted, the trainee was viewed as significantly more competent, self-confident, expert, and attractive than she was when the client's depression worsened. Ss assigned more responsibility to the client for improvement than for deterioration, but this pattern was reversed for the trainee and supervisor. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Models of Particle Dry Deposition to a Lake Surface and Some Effects of Surface Microlayers

A review of the theoretical and empirical information that has been used in modeling dry deposition over water reveals uncertainty up to the order of magnitude level for particles in the important 0.5 to 5 μm range of diameter. Much of this is attributable to uncertainty in identifying the mechanisms controlling this transport. The results do indicate that dry deposition velocities are a function of particle size as well as windspeed, surface roughness, reference height, stability, and possibly relative humidity. Surface microlayers may affect roughness, but they are unlikely to exert significant control over deposition rates except on a very local level. Estimates of potential lake-derived concentrations in air indicate that bubble ejection may prove important in evaluating net atmospheric loading rates for some metallic species and perhaps organic substances as well.