Influence of life event stress on physical illness: substantive effects or methodological flaws?

This study tests the hypothesis that the reported relationship between life event stress and physical illness is primarily a function of criterion and other content contamination in the stress measure. In particular, conventional life event measures include events related to physical health, which overlap with the criterion; events related to neuroticism, which influences the criterion; and events that are vague or subjective and could be affected by individual differences in psychological distress, response sets, and retrospective bias. In this study 386 adult males and females completed standard measures of life events and physical illness. Illness was significantly related to event subscales containing, respectively, health-related events, neuroticism-related events, and subjective events, but not to an "uncontaminated" event subscale. These results support the hypothesis of contamination and suggest that alternative approaches to the conceptualization and measurement of stress may need to be developed.     

Automated transduction of sheltered workshop behaviors

This study describes techniques for attaching transducers directly to the tools in a sheltered workshop. The resulting automatic recordings of tool usage correlate fairly highly with independent measures of work products completed.     

The square search test in connection with acoustic evoked brain stem potentials

A random sample of 15 patients suffering from multiple sclerosis without acute episodes and at least partially able to work, shows to a high degree of statistical certainty that reduction in amplitude of acoustically evoked brain stem potentials (BAEP) is closely linked with beta-weighted performance value of the square search test (QSP).     

Measures of observer agreement when binomial data are collected in free operant situations

This paper examines a model and defines reasonable assumptions underlying different measures of observer agreement for categorical data collected in free operant situations. It is assumed that two or more observers classify operant behaviors of subjects into occurrences and nonoccurrences by recognition by validated response classes (categories) such that the rates of false positives and observer biases are acceptably low. Thus errors are mostly omissions, i.e., failing to observe events that occur. Four alternative cases are derived, together with formulas for calculating significance tests, variances, and standard errors, three of which do not depend on knowledge of the proportion of time points at which the event does not occur.We wish to acknowledge NICHD Grant HD-10570, The Neuropharmacology of Developmental Disorders, George Breese, Ph.D., and C. T. Gualtieri, M.D., Principal Investigators; NIEHS Grant ES-01104; USPHS Grant HD-03110; and MCH Project 916 to the Division for Disorders of Development and Learning.     

Reinforcement of eye movement with concurrent schedules

Human macrosaccadic eye movements to two areas of a four-dial display were conditioned by concurrent variable-interval schedules of signals. Reinforcers (signals) were delivered to the two right-hand dials on one schedule and to the two left-hand dials on another, independent schedule. The use of a changeover delay between crossover eye movements and reinforcement had the effect of changing the pattern of scanning from fixating four dials in succession or in a Z-shaped pattern to scanning vertically the dials on either side with fewer crossovers. In the presence of a changeover delay, subjects matched relative eye-movement rates and relative reinforcement rates on each schedule. Rate of crossover eye movements, with a changeover delay in effect, was also inversely related to the difference in reinforcements arranged by the concurrent schedules. The results suggest that for stimuli whose critical components are arranged spatially, conditioned eye movements play an important part in selective stimulus control.     

A perception-action strategy for hummingbirds

Many human and animal tasks are thought to be controlled with the tau informational variable. It is widely accepted that controlling the rate of change of tau (tau) during decelerative tasks, such as when braking or landing, is one common perceptual control strategy. However, many tasks require accelerating before decelerating to a goal, such as reaching. An advancement of tau theory shows how a single action formula may be used to control the full action unit from initiation to peak velocity, and to rest at the goal, with the same perceptual tau information as before and accounting for the same decelerative kinematics as before. Here, we test the theory against data from high-speed video of a hummingbird flying to its flower feeder. We find that the theory accounts for 97% of the variance in the data, and thus supports it.