Abstract
Purpose: :
There is increasing concern with the frequent use of mobile phones whilst driving. Passengers are able to see the challenges the driver faces, however the person at the other end of the mobile phone cannot, and may demand high level cognitive interaction of the driver at inappropriate times. This study examined the changes in spatial sensitivity of the retina accompanying the imposition of an auditory cognitive memory task.
Methods: :
The visual fields of 33 subjects aged 18 to 24 with normal scores on the Scan C auditory figure-ground test were examined using the Medmont Monocular Driving Visual Field threshold test following the three zone method. After a baseline visual field test, another four identical format field tests were carried out following a Latin Square design either with (i) no distractions (ii) with instrumental music (iii) with a structured conversation requiring answers to questions involving spatial memory or arithmetic (iv) with music and conversation. An ANOVA was carried out to examine the effect of auditory distraction on the number of fixation losses, false positives, false negatives, relative defects, absolute defects and time taken.
Results: :
Significant (p<0.01) increases in the number fixation losses, false positives, false negatives, relative defects, absolute defects and time taken were found only for the two conditions involving auditory-cognitive tasks. Analysis of the location of the field defects revealed that there was no preference for one quadrant over another, although analysis based on annular placement in the visual field showed greatest resistance to field erosions in the 10-30° region followed by the periphery, the central 10° and finally the 30-50° region. Success in answering the questions posed did not influence the outcome of the visual field test.
Conclusions: :
Involvement in auditory-driven cognitive load impacts visual attention, accuracy and response time and may be explained by Pashler’s Bottleneck Theory of Working Memory, where ultimately attention to the cognitive task is given precedence over performance on the visual field test. Current calls to limit mobile phone conversations that require important decision-making would appear to have sound basis in science.
Keywords: visual fields • perception • memory