Speed of processing versus dual-tasking in ageing using a motor free paradigm

A common assumption is that the ability to dual-task declines as age increases, however this is largely based on research using reaction time tasks. Relatively recent research which uses titration to account for single-task ability has found that, when individual differences in ability are controlled for, there is no age-related dual-task deficit. Unlike reaction time research which relies on key presses, this study used a psychomotor speed variable (the Visual Inspection Task) to measure processing speed independently of motor-responses. This means that any age-related declines in physical dexterity or cognitive processing could not affect the overall outcome of the experiment. A Delayed Digit Span task was also carried out singularly and then the two tasks were performed together. We found that percentage accuracy decreased in both single and dual tasks as age increased, a finding that does not replicate previous research. Most importantly, we found no significant difference between age groups in dual-task cost and we also found that as age increased visual inspection speeds decreased. These findings provide support for both the titration technique and the use of psychomotor speed variables instead of reaction times. This study also shows that relatively small changes in methodology can cause substantial differences in experimental outcomes