PubMed Health⌕ Search

Biomedical subjects

H E Ross

Publications and source records attributed to H E Ross.

At least 19 recordsLinked to original sources
PubMed1992

Orientation anisotropy: some caveats in interpreting group differences and developmental changes.

We tested 220 children aged 7-12 yr and 20 university students for visual contrast sensitivity at spatial frequencies of 1.2-21.9 c/deg for vertical, horizontal and oblique sinusoidal gratings. Males had higher mean sensitivity then females and adults had higher mean sensitivity than children. Sensitivity was greater for cardinal than oblique orientations, and this oblique effect increased with spatial frequency and mean sensitivity, and with age in children. Developmental growth of oblique anisotropy can be explained by growth in contrast sensitivity. Different sizes of oblique effect were found between groups living in different locations, but variations were mainly linked to differences in age and contrast sensitivity. Genetic or environmental interpretations of group differences should be treated with caution. Other anisotropies occurred (horizontal was better than vertical and right than left obliques), but these differences were small and irregular and may represent response biases rather than neurological effects.

Adolescent↗
PubMed1990

Diagnostic validity of the MAST and the alcohol dependence scale in the assessment of DSM-III alcohol disorders.

The comparative validity of the Michigan Alcoholism Screening Test (MAST) and the Alcohol Dependence Scale (ADS) in screening for current DSM-III alcohol abuse/dependence disorders is evaluated. These scales were administered to 501 patients presenting for treatment of alcohol or drug problems. DSM-III alcohol disorders are diagnosed using the Diagnostic Interview Schedule. Receiver Operating Characteristic (ROC) analysis is used to determine optimum threshold scores for the MAST and ADS and to compare the screening ability of the two instruments. Optimum cut points for the MAST and the ADS are 12/13 and 8/9, respectively. The overall accuracy of classification for both instruments using these threshold scores is 88%. The areas under the ROC curves are .91 and .90 (SD = .02) and there are no significant differences between the MAST and the ADS in their ability to screen for alcohol abuse or dependence in this population. The MAST and the ADS correlate highly with each other (.79). The results reported in our study should be applicable to the revised DSM-III since a field trial found a high level of agreement on alcohol disorders between the diagnostic systems. Categorical versus dimensional approaches to the assessment of alcoholism are discussed.

Adult↗
PubMed1989

Diagnostic validity of the drug abuse screening test in the assessment of DSM-III drug disorders.

Diagnostic validity of the DAST was assessed using a clinical sample of 501 drug/alcohol patients. Various DAST cut-points were validated against DSM-III drug abuse/dependence criteria, as assessed by the Diagnostic Interview Schedule. The DAST attained 85% overall accuracy in classifying patients according to DSM-III diagnosis. This accuracy was maintained between DAST score cut-points of 5/6 through 9/10. Receiver Operating Characteristic analysis indicated that 5/6 was the optimum threshold score. The DAST was also correlated with demographic variables, psychiatric history, and drug use. The results showed very good concurrent and discriminant validity. This study concluded that fairly accurate estimation of DSM-III drug criteria could be made using a brief self-administered questionnaire (DAST). However, caution must be expressed when generalizing these findings to other contexts (e.g. the justice system) where subjects may have stronger motivation to under-report drug involvement.

Adult↗
PubMed1989

Alcohol and drug abuse in treated alcoholics: a comparison of men and women.

A survey of 229 male patients and 198 female patients who met lifetime DSM-III criteria for alcohol abuse or dependence was carried out in Toronto, Canada. The patients were evaluated with the National Institute of Mental Health Diagnostic Interview Schedule and other substance abuse rating scales. The prevalence of individual alcohol and drug symptoms, the patterns of abuse, and the prevalence of drug disorders were compared in the two sexes. The study patients were younger than previous treatment samples and were more likely to have other drug disorders. While the overall prevalence of drug disorders was similar in male and female alcoholics, women were more likely to abuse sedatives and minor tranquilizers while men were more prone to the abuse of cannabis and tobacco. Men continue to be more likely to have social and occupational problems resulting from alcohol abuse, to start abusing alcohol earlier in their lives, to have been abusing for longer, and to report higher quantity and frequency of alcohol consumption. With one or two exceptions, the sexes do not differ on other indicators of pathologic use, withdrawal or tolerance, medical sequelae or treatment history. While men have significantly more alcohol problems than women, as measured by the DIS and the MAST, these differences disappear when length of alcohol abuse history, antisocial personality disorder and employment status are controlled for. Similarly, when these variables are controlled for, women exhibit more symptoms of alcohol dependence as measured by the ADS. Women alcoholics come into treatment earlier in their alcoholic careers.

Adult↗
PubMed1989

Psychiatric screening of alcohol and drug patients: the validity of the GHQ-60.

The 60-item General Health Questionnaire (GHQ) and the National Institute of Mental Health Diagnostic Interview Schedule (DIS) were administered to 501 patients presenting for assessment or treatment of alcohol or drug problems at the Addiction Research Foundation, Toronto, Canada. The GHQ proved to be a useful, if limited, instrument for routine screening for psychiatric disorders other than substance abuse in this population. The sensitivity or "utility" of the test at the optimum threshold score was considerably lower in this sample than in medical or community samples. Receiver Operating Characteristic (ROC) analysis suggests a need for an upward revision of the cut-off score to 23/24 inpatients with alcohol or drug problems. At this threshold, sensitivity was 69%, specificity 75%, positive predictive value 77%, negative predictive value 66%, and overall misclassification rate 29%. A definition of "caseness" was used that included all DIS Axis I disorders with the exception of substance use and "cognitive impairment." Sensitivity of the GHQ was highest for the affective disorders (79%). False negatives accounted for the bulk (61%) of the misclassification rate. At the threshold score of 23/24, positive predictive values were greater for the unemployed and for patients with either no current substance use disorder or with both alcohol and drug disorders.

Adult↗
PubMed1988

The prevalence of psychiatric disorders in patients with alcohol and other drug problems.

A survey evaluated the lifetime and current prevalence of mental disorders in 501 patients seeking assistance with alcohol and other drug problems at an addiction research and treatment facility. Information was gathered using the National Institute of Mental Health Diagnostic Interview Schedule (DIS) and computer diagnoses were generated according to DSM-III criteria. Four fifths (78%) of the sample had a DIS lifetime psychiatric disorder in addition to substance use, and two thirds (65%) had a current DIS mental disorder. Excluding the unreliably diagnosed generalized anxiety disorder, the most common lifetime disorders were antisocial personality disorder, phobias, psychosexual dysfunctions, major depression, and dysthymia. Patients who abused both alcohol and other drugs were the most psychiatrically impaired. Patients with DIS psychiatric disorders had more severe alcohol and other drug problems. Barbiturate/sedative/hypnotic, amphetamine, and alcohol abusers were the most likely to have a DIS mental disorder.

Adult↗
PubMed1987

Sex, handedness and weight discrimination.

Manual asymmetries in weight discrimination were investigated by testing 50 subjects with their left hand and 52 with their right hand, the groups being approximately balanced for sex and hand preference. Performance was better for the left-tested group, and for strongly handed males tested with the dominant hand. Female performance was unrelated to handedness. There was no overall superiority due to sex, males being superior with the dominant hand and females with the nondominant hand. The results are interpreted in terms of spatial hemisphere involvement, hand dominance, and the greater hemispheric specialization of males.

Adult↗
PubMed1987

The nature of sensorimotor adaptation to altered G-levels: evidence from mass discrimination.

Mass discrimination is impaired under zero G compared to 1 G. This is partly due to loss of weight information (a reduction in z-axis pressure stimulation), and probably also to incomplete adaptation to the reduced G-level. Maladaptation to an increased G-level postflight causes objects to feel too heavy and weight discrimination to be impaired. Video tapes of hand movements while shaking test objects were made before, during, and after the D-1 Spacelab mission. Movements were faster inflight than preflight, slowed down postflight and returned to baseline by about the third day. Corresponding changes in movement amplitude also occurred. Errors of weight or mass perception during the maladaptation phase may be due to both inadequate monitoring of command signals and to inappropriate scaling of afferent signals. High-acceleration shaking was found to improve mass discrimination but impair weight discrimination.

Adaptation, Physiological↗
PubMed1986

Mass-discrimination in weightlessness and readaptation to earth's gravity.

Five members of the first Spacelab mission (STS-9) were tested on several occasions for weight-discrimination before and after the flight, and for mass-discrimination under microgravity in flight. Thresholds for mass-discrimination were higher than for preflight weight-discrimination by a factor of about 1.8, and there was no clear evidence of improvement throughout the ten day mission. Too few tests were conducted to monitor the improvement during the first two days of flight, when adaptation to weightlessness may have occurred. Subjects reported perceptual aftereffects of body heaviness for two or three days after the flight. Their weight-discrimination thresholds were raised during this period, when they were re-adapting to normal gravity. Incomplete adaptation to altered arm weight can only partly explain the raised threshold for mass-discrimination in microgravity. Differences in the sensory information available with and without gravity are discussed.

Adaptation, Physiological↗
PubMed1983

Optic-flow and cognitive factors in time-to-collision estimates.

Time-to-collision (Tc) estimates were obtained from twenty-four subjects who viewed film clips for varying lengths of time. The film clips showed the view from a moving car travelling towards a stationary target car, but ended 100 m before reaching the target. Viewing time varied from 2 to 6 s, approach velocity from 40 to 100 km h-1, and Tc from 3.6 to 9.0s. It was hypothesised that, if time were needed to calculate Tc, the accuracy of Tc estimates would increase with viewing time up to some maximum. However, the results showed no effect of viewing time, and this was taken to indicate that estimates were based upon information directly available from the changing optic array at the eye of the observer. A significant velocity effect was found, accuracy increasing with velocity. Since velocity was inversely correlated with Tc, this probably implies that accuracy decreases with increasing Tc. Sex differences were found, with males giving higher and more accurate estimates than females. The relevance of these findings to the nature of Tc information is discussed.

Adolescent↗