Reginald E. Quilter

Sustained attention in adulthood: a unique, large-sample, longitudinal and multicohort analysis using the Mackworth Clock-Test.

A cross-sectional sample of men (n = 177) tested in 1962-1964, and men (n = 188) and women (n = 113) tested in 1980-1984, and a longitudinal sample (n = 53) of men tested in 1962-1964 and 1980-1984, were used to investigate age differences and 18-year age changes on a 62-min sensory vigilance task that made virtually no demand on memory, the Mackworth Clock-Test. Age differences and changes in the vigilance decrement were also examined. No age differences or changes were obtained for detection accuracy. Target response time showed significant age-related 18-year longitudinal changes and one significant cross-sectional age difference; the overall age effect was of a U-shaped function with a minimum at middle age. Age differences and changes were obtained in a measure of arousal: skin potential response latency; the overall age effect was also consistent with a U-shaped function. There was little consistent evidence of a differential effect of age on the vigilance decrement. Outcomes contradictory to Surwillo and Quilter (1964) and Quilter, Giambra, and Benson (1983) are reconciled through additional statistical analyses.

A two-term exponential functional description of the time course of sustained attention

A consensus of critical reviews of single-process theories of vigilance or sustained attention has supported the view that the vigilance decrement must be the result of two or more coacting or interacting processes or systems. One theoretical position, as well as the ubiquity of exponential functions in characterizing the time course of biological processes, led to the hypothesis that the time course of sustained attention could be best modeled by the function A[e-T1-time 11(1 + eT2*time)]. An experimental test (n = 613) using 23 points showed that this function accounted for 96.7% of the variance of detection accuracy and was 1.2 times better than a previously proposed single-term model. All parameter estimates were highly statistically significant. Fits to data from three other studies also supported the two-term exponential model. The model fitted target response time less well, accounting for 75.6% of the variance.

The relationship of age and extraversion to arousal and performance on a sustained attention task: a cross-sectional investigation using the Mackworth Clock-Test

Abstract H. J. Eysenck has postulated—and received some empirical support for—an inverse relationship between extraversion and arousal level. Age and extraversion have been found to be negatively correlated. These two outcomes led to the conclusion that arousal level must be increasing with age. This conclusion, however, runs counter to evidence which indicates a lowered arousal with old age. In an attempt to resolve this apparent conundrum a sample of 134 men from 32 to 91 years of age participated in the Mackworth Clock-Test of vigilance during which their arousal level was measured by electrodermal activity. One measure of arousal was unrelated to extraversion both within and across young, middle, and old age groups. For the second measure of arousal as age increased a decrease in arousal level was observed and the relationship of extraversion and arousal was found to be a function of age: inverse for young, none for middle-aged, direct for old. In addition no relation was found between vigilance performance and extraversion.

A simple method for preparing silver-silver chloride electrodes for recording of skin-potential.

Although stable, high-impedance, D.C. amplifiers in the 0.1 my. range have made recording of the Tarchanoff effect available to most laboratories, electrodes continue to pose a problem. In order to measure accurately electrical potentials of the skin, the bias potential of the electrodes must be negligible at the level of amplification used and stable (relatively free from drift) over the period of time the electrodes are attached to a subject. While the Ag-AgC1 electrode has usually been preferred over all others, numerous different types and variations have been used.

Performance on a sustained attention task as a function of strategy: A cross-sectional investigation using the Mackworth clock-test

In an attempt to ascertain strategies used during a Mackworth clock-test vigilance task, we had 128 men, 18 to 89 years old, answer a series of open-ended questions immediately following the task. Each of the posttask response protocols was assigned to one of six strategies by two judges. Age was not related to the strategy used, but strategy was found to be significantly related to target detection accuracy. Strategies based upon active mental involvement in the vigilance task produced the greatest level of target detection, whereas a strategy based only upon self- arousal manipulation through limited physical movement produced the poorest target detection. Strategy had no effect on the time course of performance.

A simple, inexpensive, constant-flow pump for delivering liquid reinforcers

A liquid reinforcer, controlled by a solenoid valve venting to atmospheric pressure, eliminates the chance of interrupted flow due to a clogged valve. The device maintains a constant flow at adjustable rates, and is inexpensive and easy to construct.