Methodological and theoretical implications of intraindividual variability in perceptual-motor performance.

As an individual differences variable, lability (within-person variability) has often been neglected even though it has been shown to predict key outcomes such as mortality. We examine intraindividual variability in perceptual-motor performance and relate it to chronological age in a sample of adults. The magnitude of between-session variability was found to average between 25% and 50% of the between-person variability and was equivalent in magnitude to the variation that was apparent across an age range of 12 to 27 years in cross-sectional comparisons. Age is related to the magnitude of intraindividual variability, which in turn is negatively related to performance on other cognitive tasks. Various implications of the findings are discussed.