Free and focused attention in young and aged listeners using randomized dichotic digits test

Background and Aim: Aging is associated with reduced cognitive abilities including attention and memory. There is some evidence that shows randomized dichotic digits test (RDDT) has enough difficulty to show the ear asymmetry in dichotic listening. This study aimed to compare the effect of free and focused attention on dichotic listening ability of young and elderly listeners. Methods: The cross-sectional comparative study was performed on fifty right-handed young (18-25 years old) and fifty right-handed aged (60-80 years old) with equal gender ratio. Recognition performance of right and left ears were compared in free and focused attention conditions. Results: In the free attention condition, mean percent correct of right and left ears of aged group (83.1 and 61.5 respectively) was significantly lower than the scores of the young group (92.8 and 84.3 respectively with p < 0.001). In focused attention to right, there was no statistically significant difference between mean of performance of the two age groups (p=0.407); however, aged group obtained significantly lower mean score in focused attention to left ear (p < 0.05). Conclusion: Random presentation of one-, two- and three-pair of dichotic digits resulted in diminished performance of both ear of aged group in free attention and left ear performance in focused attention conditions. Lower score of aged group in randomized dichotic digits test can be better explained by combinatory (structural and attentional) model of dichotic listening.