EFFECTS OF AGE ON VISUAL NEURAL PROCESSING: IMPLICATIONS FOR MATURE DRIVERS
 
Herkes, K. and Conlon, L., Griffith University, Australia
 
An increasing number of mature persons are driving motor vehicles, and many of them are involved in road traffic accidents. Research has primarily focussed on driving behaviours and a variety of retinal diseases. More recently, research indicates that some neural visual processing functions may become less effective with age. This study was conducted to determine whether an age-related decline occurs in the magnocellular processing subsystem that is involved in processing visual stimuli. Driving a motor vehicle requires a high level of sensitivity to motion and the ability to rapidly process temporal stimuli. The magnocellular processing subsystem is responsive to both of these functions. Participants were 37 young and 36 mature drivers. Two experiments were performed to measure processing in the magnocellular and parvocellular processing subsystems. A measure of global motion processing and a temporal visual task to measure rapid sequential processing, were performed to investigate magnocellular processing. A measure of global form processing and a visual spatial counting task were performed to investigate parvocellular functioning. A statistically significant difference between mature and young drivers on performance of tasks measuring magnocellular performance was found, indicating an age-related decline in that subsystem. Tasks measuring parvocellular processing, indicated no age-related decline in that system. The results also gave support to the theory of loss of spatial memory, as a function of age. The findings, which are discussed in terms of age related neural loss within the magnocellular subsystem, have implications for mature drivers.