Marijuana's effects on human cognitive functions, psychomotor functions, and personality

Marijuana is complex chemically and not yet fully understood, but it is not a narcotic. Like alcohol, marijuana acts as both stimulant and depressant, but it lingers in body organs longer than alcohol. Smoking marijuana can injure mucosal tissue and may have more carcinogenic potential than tobacco. Research has indicated that marijuana intoxication definitely hinders attention, long-term memory storage, and psychomotor skills involved in driving a car or flying a plane. Expectations and past experience with marijuana have often influenced results more than pharmacological aspects have. Marijuana has triggered psychotic episodes in those more vulnerable. Psychological and some instances of physiological dependence on marijuana have been demonstrated. As a psychoactive drug, marijuana surely alters mental functioning. Although it is possible that chronic use of marijuana produces irreversible damage to mind or brain areas, this has not been determined by research.     

Attentional deficits in head-injured children: An information processing analysis

Attentional problems of closed head-injured (CHI) children were examined using an information processing (IP) approach. Based on Sternberg's (1969) additive factor method (AFM), the study examined attentional processes in terms of four stages and their corresponding task variables. A visual-spatial choice reaction-time task was undertaken with two groups of CHI children (severe and mild to moderate) and corresponding matched control groups. Results indicated that for this task both the CHI and the normal children exhibited a similar mode of linear, sequential information processing. It was found that the severe group was impaired not only in terms of slowed motor execution but also in terms of response selection. This group showed no impairment on the feature extraction, stimulus identification, and motor adjustment stages of processing. No evidence of impairment on any of the stages was found for the mild group. The utility of the AFM and implications of these findings are discussed with reference to CHI children and to neuropsychological assessment and rehabilitation.     

Measuring the stop point of rapid smoking

A method and an apparatus are described for measuring the point at which subjects elect to stop smoking when cigarette smoke is delivered more rapidly than in typical smoking. The device allows either the subject or the experimenter to control the volume of smoke and the interval between puffs. The device delivers reliable quantities of particulate matter from cigarette smoke. Subjects retested a week apart exhibited consistent stopping points.     

Object Recognition Difficulty in Visual Apperceptive Agnosia

Two patients with visual apperceptive agnosia were examined on tasks assessing the appreciation of visual material. Elementary visual functioning was relatively preserved, but they had profound difficulty recognizing and naming line drawings. More detailed evaluation revealed accurate recognition of regular geometric shapes and colors, but performance deteriorated when the shapes were made more complex visually, when multiple-choice arrays contained larger numbers of simple targets and foils, and when a mental manipulation such as a rotation was required. The recognition of letters and words was similarly compromised. Naming, recognition, and anomaly judgments of colored pictures and real objects were more accurate than similar decisions involving black-and-white line drawings. Visual imagery for shapes, letters, and objects appeared to be more accurate than visual perception of the same materials. We hypothesize that object recognition difficulty in visual apperceptive agnosia is due to two related factors: the impaired appreciation of the visual perceptual features that constitute objects, and a limitation in the cognitive resources that are available for processing demanding material within the visual modality.     

Counselor Competency in the Courtroom

This article outlines general courtroom procedures and offers systematic practical advice for the counselor testifying as an expert witness. Major topics include the counselor role in court, preparing for testimony, answering questions, and dealing with the cross-examination.     

Interactive effects of item content and ethnic group membership on performance on the McCarthy scales

The study investigated cultural bias in the 46 verbal items of the McCarthy Scales of Children's Abilities (MSCA). The verbal items of the MSCA were administered to 59 Anglo and 59 Mexican-American subjects matched for age and sex. The responses of two groups of subjects on these items were analyzed by log-linear technique using the likelihood ratio chi-square statistic. The analysis of the data revealed that the majority of the verbal items of the MSCA are free from cultural bias. Only three items of the MSCA V-scale reflected systematic cultural bias. Two of these items are from the Word Knowledge II Subtest and the third one is from the Opposite Analogies Subtest. Suggestions for the use of the MSCA with children from minority cultures are made.     

An analysis of interference in recognition memory

A stimulus-sampling model of recognition memory is presented that predicts both proactive and retroactive interference. To test the predictions of the model, a recognition memory experiment was carried out using a standard proactive-retroactive design with a forced-choice task. Both accuracy and latency were measured. The data showed, as predicted, equal proactive and retroactive effects on accuracy, providing solid support for the model. The interference effects are interpreted in terms of the model as arising from an increase in indirect marking, the marking of shared stimulus elements in words other than the study word. The model has two parameters representing the rate of indirect marking for high-frequency and low-frequency words and two parameters reflecting the efficiency of direct marking. The latency results completely paralleled the accuracy findings, showing proactive and retroactive effects. A possible extension of the model to handle latencies is considered.