Marshall B. Jones

The Familial Aggregation of the Lesser Variant in Biological and Nonbiological Relatives of PDD Probands: a Family History Study

OBJECTIVE To determine the risk of the lesser variant (or PDD-like traits) in the biological and nonbiological second- and third-degree relatives of PDD probands using a screening questionnaire and to investigate the extent to which the risk of the lesser variant differs according to various characteristics of the proband. METHOD The sample consists of a series of 34 nuclear families with 2 affected PDD children (multiplex, MPX), 44 families with a single PDD child (simplex, SPX), and 14 families who adopted a PDD child. Data on characteristics of the lesser variant in 1362 biological and 337 nonbiological second- and third-degree relatives were collected from parents by telephone interview and from several maternal and paternal relatives by questionnaire. RESULTS All components of the lesser variant were more common in biological relatives (BR) than nonbiological relatives (NBR), confirming the familial aggregation of the traits. Proband characteristics associated with an increased risk of the lesser variant in relatives were a higher level of functioning and coming from a MPX family. CONCLUSIONS These findings on the familial aggregation of the lesser variant suggest that the genes for PDD also confer susceptibility to the lesser variant and that PDD may be a genetically heterogeneous disorder.

Lack of cognitive impairment in first-degree relatives of children with pervasive developmental disorders

OBJECTIVE The objective of this study was to test the hypothesis that mild cognitive impairments aggregate in the unaffected first-degree relatives of probands with autism or pervasive developmental disorders (PDD). METHOD The unaffected siblings and parents of 52 PDD probands and 33 Down syndrome and low birth weight controls were administered a battery of psychometric tests. The tests included measures previously found to be depressed in siblings of autistic children as well as cognitive deficits seen in PDD subjects of normal IQ. In addition, the Vineland Adaptive Behavior Scales were administered to siblings to measure the social-communication impairments found in PDD. RESULTS Neither the siblings nor parents of the PDD probands demonstrated lower cognitive or adaptive behavior scores compared with controls. Developmental histories did not reveal greater rates of social, cognitive, or language delays, nor was there evidence to suggest that relatives of subgroups of PDD probands were different from each other. CONCLUSION These findings indicate that, apart from relatives with PDD, cognitive and social impairments do not aggregate in the families of PDD probands.

Overcoming Unreliability in Operational Measures: The Use of Surrogate Measure Systems

Improved assessment of operational performance is critical for studies of selection, training and human engineering as well as those examining the performance effects of environmental changes, chemicals or other stressors imposed by military duties. The present discussion focuses on what we consider to be the major problem with such enterprises – the lack of sensitivity of operational measures because of poor reliability. The well-documented impact of low field measure reliability includes the inability to demonstrate differences resulting from experimental treatments and the chronic underrepresentation of validity in predictive studies. This paper describes a general methodology for using specially-developed performance batteries as surrogates for real-world performances, in particular for determining whether such performance may be disrupted by environmental or chemical agents. The logical and metric rationale of surrogate measurement is presented, and the advantages and disadvantages are discussed and compared to alternative approaches (job samples, synthetic tasks, etc.).

Line-gap discrimination of the skin.

In three experiments, different influences on the ability to separate stimuli on the skin or detect gaps between them were investigated. The first study presented a new method of studying gap detection which eliminates methodological difficulties inherent in the classical two-point method, and it was shown that thresholds decrease with extended practice on a given skin area. The second study investigated the ability to detect point stimuli inserted within gaps and demonstrated that the perception of such stimuli is suppressed when they are centered in gaps that are discriminable. Also, it was shown that the two-gap threshold is nearly twice the single-gap threshold, and therefore distance between edges is more important than amount of unstimulated skin for gap discrimination. In the third study, the amount of stimulation on each side of tactile gaps was varied, and it was determined that this does not significantly affect gap detection.

A Video Test for Prediction of Tank Commander Performance

Two experiments were conducted to determine the utility of a microprocessor-based video test for the prediction of tank commander performance. A task analysis identified elements to serve as simulated job samples. Significant correlation coefficients were obtained between test performance and supervisory rankings, but were positive for two groups and negative for two groups. It was concluded that the predictive validity occurred by chance.

Isoperformance: Trading off Selection, Training, and Equipment Variations to Maintain the same Level of Systems Performance

This paper details an Air Force sponsored project known as Isoperformance. Isoperformance (iso meaning same) is a conceptual approach to human factors engineering. The focus of isoperformance is that the same level of performance can be attained by different combinations of personnel, training, and equipment. This goal is, once these combinations have been determined, a choice among them can be made in terms of maximum feasibility or minimum cost. The program takes into account human engineering, personnel, and training research. The specific focus of this paper will be the interactive computer program. Input to the isoperformance program, made by the user, includes the system, the task, a quantified definition of proficient performance as well as other specifications.

Criteria of Performance Tests for Fitness-for-Duty Assessment

Fitness for duty (FFD) tests can be used in workplace settings to identify performance impairment due to alcohol/drugs, fatigue, illness, etc. Accordingly, FFD tests must be both sensitive (able to detect impaired individuals), and more importantly, specific (very few false positives). However, high specificity for performance tests can be achieved only at the price of low sensitivity. A formula for the “sensitiveness” of FFD tests (the proportion of impaired persons detected by the test) is provided to permit comparison of performance and chemical tests based on the tests “sensitivity” and the rate at which persons are tested. An illustrative study is also provided to show that performance tests can meet the requirements of FFD testing. Results of four performance tests, which showed unequivocal deterioration when repeatedly administered to participants over a 24-hour testing period, are provided to demonstrate calculations of the sensitivity and specificity of the tests to fatigue effects.

Comparison of Two Batteries for Fitness-for-Duty Testing

Many businesses seek to deter impairment due to alcohol and other drugs (AODs) on the job and feel a need to detect impaired performance due to AODs directly, rather than by inference from chemical testing. Industry requirements for a performance test to be used in a fitness-for-duty program are that the test have very high specificity and sufficient sensitivity to detect many impaired workers much of the time. To determine if a newly developed computerized temporal acuity test battery had the requisite specificity and sensitivities comparable to those previously obtained with a computerized cognitive performance test battery, performance on the two test batteries was assessed before and after the administration of alcohol. Results indicated that the temporal factors tests did not exhibit sufficient specificity to satisfy industry requirements, however the cognitive tests exhibited high sensitivity and adequate specificity.

A Temporal Factors Battery for Studying Individual Differences in Perception

Individual differences in perception have drawn increased attention from training and task-performance communities. If perceptual tests are to be utilized to train, predict, or optimize performance, then they need to be studied and evaluated as differential measures. In this study, the reliability and individual differences for a perceptual test battery (seven tasks) were investigated. The participants (10 males, 11 females) completed five trials of the test battery within a ten day span. In general, the results of this study are positive. Six of the seven tasks showed sizable individual differences and four of the seven were reliable. The three tasks that showed unreliability have since been modified and need to be formally studied.

Isoperformance: A Methodology for Human Factors Engineering Design

The literature of applied psychology rarely, if ever, allows an unambiguous answer to a particular problem. Almost always there is a hiatus between what is known and what one wants to know. If the tasks are the same, personnel, performance measures, temporal relations or environmental conditions are different. Oftentimes nothing is quite the same as what has been studied in the literature. Inevitably, these gaps are closed by “expert judgment.” People who are experienced in the field extrapolate from what has been studied to the real-world case in hand. This inevitability is not, however, the end of the matter. Expert judgment can be utilized in many different ways and some ways are better than others. The principal issues are: precisely what are the experts to be asked, how is their consensus to be determined, and how is that consensus to be used relative to the real-world problem in hand. This discussion will describe one way of answering these questions. It is called “isoperformance.” The key feature of this approach is the design of an “ideal experiment.” This experiment then functions as a framework for both what is known in the literature and expert judgment.