Age-related differences in performance and stimulus processing in dual task situation

Competition for limited processing resources is most critical in dual-tasks which incorporate cognitive and motor demands. Performance is usually diminished with increasing age in such tasks. This decline is relevant for activities in real life like driving. In the present study we aim to examine if there are age-related differences in stimulus processing in a dual-task and if these differences have an impact on performance of a driving-like tracking task. Young and older participants performed a dual-task consisting of a tracking task and a visual attention task. Alongside, the EEG was recorded for calculating the P300 (P3) of the event-related potential as a reflection of controlled stimulus processing. In the visual attention task older vs. young participants showed more misses and false alarms. For young participants the P3 shows an expected pattern of higher amplitudes for relevant compared to irrelevant stimuli. This was not found for the older participants. A general age-related decline in tracking performance was relatively more pronounced if a secondary motor response was required in the visual attention task and also after irrelevant stimuli. The results suggest that older compared to young participants had greater difficulties to differentiate between relevant and irrelevant stimuli in a dual-task situation as they probably apply comparable attentional resources to all stimuli. This may also explain the higher error rates. These results have important implications for the understanding of age-related stimulus processing in dual and multi task situations in real life as for instance driving.

► Differentiating between relevant and irrelevant stimuli was impaired with age.
► After correct target identification older people's further stimulus processing was as effectively as in young people.
► Older people's tracking performance was impaired after 13 additional motor response.