Reaction Time Performance in Healthy Adults as an Effect of Age and Hand Preference Using the CRTT

Background: The Computerized Revised Token Test (CRTT) is a standardized assessment of language processing abilities. The test requires perceptual, motor, and cognitive skills that may impact patient performance. A battery of reaction time tasks (CRTT-RT) was developed to assess these skills on a more basic, nonlinguistic level in order to assess a patient’s perceptual-motor-cognitive skills’ contribution to their CRTT language performance. Normative data on the CRTT-RT Battery do not currently exist across age and for right and left hands. The purpose of this study was to investigate the effect of age and hand preference on the simple and choice reaction time (RT) tasks included in the CRTT-RT Battery. Procedures: Sixty-four healthy, normal adults completed the CRTT-RT tasks and the CRTT-R-WF version of the CRTT with both their right and left hands. Participants included 32 younger adults (20-32 years; 16 male, 16 female) and 32 older adults (65-78 years; 16 male, 16 female). For this study, the CRTT-RT data were analyzed to evaluate the effects of age and hand preference on speed and accuracy of responses. Results: Statistically significant main effects were determined for both age and hand preference on all RT tasks combined. Age effects were additionally observed on individual RT tasks, where the older group performed slower (increased RT) than the younger group. Hand preference effects were observed on 4 of the 6 RT tasks, those that required motor movement control and response mapping, with the left hand performing significantly slower. A significant interaction between age and hand was observed for CRTT-RT Task 3 (Movement), where the older group demonstrated an over-additive slowing with the left hand. Accuracy of responses on the choice RT tasks demonstrated non-substantive differences between age and hand. Conclusions: Slowing in reaction time performance on the CRTT-RT Battery is evident with increased age as well as non-preferred hand use with a computer mouse. Theories of generalized slowing with age, increased task complexity, cognitive load, and automaticity are explored as potential explanations for the obtained results.