The time course and significance of cannabis withdrawal

Withdrawal symptoms following cessation of heavy cannabis (marijuana) use have been reported, yet their time course and clinical importance have not been established. A 50-day outpatient study assessed 18 marijuana users during a 5-day smoking-as-usual phase followed by a 45-day abstinence phase. Parallel assessment of 12 ex-users was obtained. A withdrawal pattern was observed for aggression, anger, anxiety, decreased appetite, decreased body weight, irritability, restlessness, shakiness, sleep problems, and stomach pain. Onset typically occurred between Days 1-3, peak effects between Days 2-6, and most effects lasted 4-14 days. The magnitude and time course of these effects appeared comparable to tobacco and other withdrawal syndromes. These effects likely contribute to the development of dependence and difficulty stopping use. Criteria for cannabis withdrawal are proposed.     

Latent growth curve analyses of accelerating decline in cognitive abilities in late adulthood

Latent growth models were applied to data from the Swedish Adoption/Twin Study of Aging to discover if the rate of change in cognitive performance increased from middle age to later adulthood. The sample included 590 participants aged 44 to 88 years at first measurement. Data were gathered at 2 follow-up occasions at intervals of 3 years. Cognitive ability was assessed through 11 tests that tapped crystallized, fluid, memory, and spatial abilities and perceptual speed. Results indicated stability for measures of crystallized ability, linear age changes for many cognitive abilities, and a significant acceleration in linear decline after age 65 for measures with a large speed component. Gender differences were found only in mean level, not in rate of decline.     

Functional analysis and treatment of verbal perseverations displayed by an adult with autism

The function of perseverative speech for an adult man who had been diagnosed with autism and mental retardation was examined. Results showed that verbal perseverations were maintained by social attention. An intervention consisting of differential reinforcement of appropriate verbal responses and extinction of perseverative verbal responding was effective in decreasing verbal perseverations.     

Functional analysis and treatment of self-injurious behavior in young children a summary of 30 cases

The assessment and treatment of self-injurious behavior (SIB) has received much attention in the literature; however, few studies have focused on early intervention for this behavior. In the current study, functional analyses with developmentally appropriate modifications were conducted in an outpatient clinic with 30 children (aged 10 months to 4 years 11 months) to assess SIB and problem behavior in its early stages. The reported mean age of SIB onset was 17 months, and head banging was the most prevalent topography. Functional analyses identified sources of reinforcement for SIB in 62.1% of cases; with the inclusion of all forms of problem behavior, sources of reinforcement were identified for 87.5% of cases. Function-based treatments were developed for 24 cases, with functional communication training prescribed most often (70.8% of cases). Implications of these findings for the development of early intervention programs for SIB are discussed.     

A field study of frame-of-reference effects on personality test validity

As part of a test validation study at a major U.S.-based airline, the authors tested the effects of providing an "at work" frame-of-reference on the validity of the NEO Five-Factor Inventory among a sample of customer service supervisors (N = 206). Frame-of-reference moderated the validity of the Extraversion and Openness to Experience subscales after controlling for cognitive ability. In addition, the frame-of-reference personality test showed incremental validity over cognitive ability (deltaR2 = .16), but the standard personality test did not (deltaR2 = .05). The authors' discussion focuses on implications for personality theory and research and on implications for increasing the validity of personality tests in organizational settings.     

Sequential evaluation of behavioral treatments and methylphenidate dosage for children with attention deficit hyperactivity disorder

We used a sequential approach to evaluate the relative and combined effects of different types of behavioral treatments, as well as dosage of methylphenidate (MPH), on the disruptive behavior of 3 students who had been diagnosed with attention deficit hyperactivity disorder. Results showed that individualized behavioral treatments produced decreases in disruptive behavior equivalent to MPH for all 3 participants and demonstrated the need to evaluate behavioral treatments and medication dosage on an individual basis.     

Drivers' compliance with speed limits: an application of the theory of planned behavior

The theory of planned behavior (TPB; I. Ajzen, 1985) was applied to drivers' compliance with speed limits. Questionnaire data were collected for 598 drivers at 2 time points separated by 3 months. TPB variables, demographic information, and self-reported prior behavior were measured at Time 1, and self-reported subsequent behavior was measured at Time 2. In line with the TPB, attitude, subjective norm, and perceived control were positively associated with behavioral intention, and intention and perceived control were positively associated with subsequent behavior. TPB variables mediated the effects of age and gender on behavior. Prior behavior was found to moderate the perceived control-intention and perceived control-subsequent behavior relationships. Practical implications of the findings for road safety and possible avenues for further research are discussed.     

Conscientiousness, autonomy fit, and development: a longitudinal study

The authors examined employee development and its relationship with Conscientiousness and person-environment fit (in terms of needs and supplies of autonomy). They hypothesized that Conscientiousness would be positively associated with development but only when employees felt that the autonomy supplied by the organization did not fit their needs. In other words, whereas Conscientiousness could supply the dispositional resources for development, misfit was needed to create the need for development. The results supported the authors' predictions. Conscientiousness was positively related to development but only when employees were misfits with respect to autonomy. Employee involvement in development activities was then linked to subsequent fit.     

Transactive memory in organizational groups: the effects of content, consensus, specialization, and accuracy on group performance

Previous research on transactive memory has found a positive relationship between transactive memory system development and group performance in single project laboratory and ad hoc groups. Closely related research on shared mental models and expertise recognition supports these findings. In this study, the author examined the relationship between transactive memory systems and performance in mature, continuing groups. A group's transactive memory system, measured as a combination of knowledge stock, knowledge specialization, transactive memory consensus, and transactive memory accuracy, is positively related to group goal performance, external group evaluations, and internal group evaluations. The positive relationship with group performance was found to hold for both task and external relationship transactive memory systems.     

An examination of the value of the generation effect for learning new material

The generation effect involves an improvement in memory when learners must complete or modify materials. Several researchers have suggested that this effect involves enhanced access to learners' existing memory representations; therefore, the effect should be less effective with meaningless, low meaningful, or unfamiliar material. In the present study, the authors conducted 4 experiments in which legal nonwords were used, and they found no generation effect. In another 2 experiments in which familiar clichés were contrasted with new sentences and with unfamiliar sentences from textbooks, the results showed a greatly reduced generation effect for the new, unfamiliar material. Those findings suggest that memory strategies that depend on the generation effect will have limited effectiveness when they are applied to new or unfamiliar material.