Synapses,Schizophrenia, and Civilization: What Made Homo Sapient?

Progress in technology has allowed dynamic research on the development of the human brain that has revolutionized concepts. Particularly, the notions of plasticity, neuronal selection, and the effects of afferent stimuli have entered into thinking about brain development. Here I focus on development from the age of four years to early adulthood, during which a 30 percent reduction in some brain synapses occurs that is out of proportion to changes in neuronal numbers. This corresponds temporally with changes in normal child behavior from the loose‐associative, almost schizoid, thinking and art of the four‐year‐old to the more trained, or disciplined, or acculturated—and restrained—personality of the young adult. I propose that the synaptic changes can best be thought of as a winnowing process likely subject to environmental influences. Acquisition of language and the ability to link linguistic cognition to the plastic development of the brain provide a potentially powerful means of explaining the evolutionally explosive development of human cognition and culture. Schizophrenia, a disease that can be envisioned as representing a derangement of synaptic maturation, may provide an entry into the search for genes controlling the processes mediating the unprecedented development of Homo sapiens over the past 40,000 to 70,000 years. The recently completed mapping of the genome of the chimpanzee provides a new frame of reference that may speed the search.     

Are high school students accurate or clueless in estimating substance use among peers?

The purpose of this study was to assess adolescents' estimations of the prevalence of alcohol and other drug use and to examine the consistency between these estimations and reported use. A survey was administered to 223 students in three northwestern U.S. high schools. Results showed that students in each of the three high schools grossly overestimated the prevalence of substance use when compared to self-reports of use. Still, students were not entirely clueless about the relative normativeness of substance use when comparing estimates and rates of use among the three schools. The school with the highest estimated prevalence of a particular substance use behavior generally also had the highest self-reported use of that same substance. These findings imply the need for high school personnel to provide students with accurate information about the actual prevalence of substance use within each school.     

Mental and physical practice schedules in acquisition and retention of novel timing skills

Research has indicated that random physical practice of a motor skill enhances effects of long-term learning more than blocked practice. Moreover, the use of mental rehearsal coupled with physical practice has been shown to accelerate motor skill acquisition in many different contexts and is better than no practice at all. Others have found that some mental rehearsal strategies are better than others for maximizing performance. This study examined how combinations of mental and physical practice schedules affected the learning of a coincidence timing task. 30 college students were randomly assigned to one of four treatment groups involving combinations of imagery and physical practice. Three tasks were utilized, each involving a particular speed (slow, medium, fast) on the Bassin Anticipation Timer. Conclusions were based on a three-way analysis of variance, using type of mental practice, type of physical practice, and sex as between-group factors, conducted separately for acquisition and retention trials. Type of physical practice was significantly related to performance. On the acquisition trials, random practice was associated with larger mean errors than blocked practice; however, the reverse was true for retention trials. There was no significant effect of type of mental practice in either the acquisition or retention phase. Sex was significantly related to performance for the retention trials only, where the 15 men made smaller errors than the 15 women.     

Analysis of precurrent skills in solving mathematics story problems

We conducted an analysis of precurrent skills (responses that increase the effectiveness of a subsequent or "current" behavior in obtaining a reinforcer) to facilitate the solution of arithmetic word (story) problems. Two students with developmental disabilities were taught four precurrent responses (identifying the initial value, change value, operation, and resulting value) in a sequential manner. Results of a multiple baseline design across behaviors showed that the teaching procedures were effective in increasing correct performance of each of the precurrent behaviors with untaught problems during probes and that once the precurrent behaviors were established, the number of correct problem solutions increased.     

Improving staff nutritional practices in community-based group homes: evaluation, training, and management.

We evaluated the effectiveness of a staff training and management package on nutritional practices in two community-based group homes serving adults with developmental disabilities. Food storage, menu development, and meal preparation were trained in a multiple baseline format, followed by supervisor feedback. All staff behaviors increased after training and were maintained for up to 1 year. Biological indices reflected collateral improvements in the health of consumers, and surveys of staff and parents established social validity.     

Anxiety reactivity and anxiety perseveration represent dissociable dimensions of trait anxiety

Trait anxiety is an individual-difference variable reflecting variation in state-anxiety elevations resulting from exposure to a stressor. It is usually measured using questionnaire instruments, such as the Spielberger State-Trait Anxiety Inventory (STAI-T). The present research conceptually distinguishes, and independently assesses, two hypothetical dimensions of anxiety vulnerability which, it is argued, could plausibly make independent contributions to variance in trait-anxiety scores. These dimensions are anxiety reactivity, the probability of experiencing an anxiety reaction to a stressor, and anxiety perseveration, the persistence of anxiety symptoms once elicited. Participants were asked three questions about each STAI-T item. The traditional STAI-T question assessed how much of the time this symptom was experienced; the anxiety-reactivity question assessed the probability of experiencing the symptom in response to a stressor; and the anxiety-perseveration question assessed how long the symptom persisted, if elicited. Regression analysis determined that anxiety reactivity and anxiety perseveration scores both accounted for independent variance in trait-anxiety scores. It is argued that models of anxiety vulnerability should seek to differentiate both the causes and the consequences of elevated anxiety reactivity and increased anxiety perseveration. (PsycINFO Database Record (c) 2012 APA, all rights reserved).