Development of peripheral vision tests for driver assessment

Abstract

In the interests of identifying older drivers at higher risk of crashing, with a view to restricting their driving, fitness to drive tests require development and validation. One particular test that makes claim for inclusion in any battery of fitness to drive tests is the Useful Field of View test (UFOV)1. UFOV subtests appear to depend heavily on speed of visual processing, and on indexing crowding in peripheral vision. However, UFOV is a proprietary instrument and other custom software is available for measuring speed of visual processing and crowding in peripheral vision. Sixty participants aged over 60 completed UFOV. They also completed inspection time (IT), a measure of speed of visual processing, and crowding across the visual field (CAVF), a measure indexing effects of strength of crowding in peripheral vision. Thus, the current study compared performance on UFOV, inspection time (IT) and crowding across the visual field (CAVF). The main outcomes here were that the IT and CAVF measures had high test-retest reliability over a period of about one week and did not exhibit statistically significant practice effects. By way of contrast, although UFOV measures were also highly reliable, two of three UFOV measures, Divided Attention and Selective Attention, showed practice effects; the third measure, Processing Speed, showed severe range restriction in the current sample of healthy older adults. Correlations between CAVF, IT and UFOV Selective Attention were very high. These outcomes suggests that IT and CAVF together may well prove appropriate and useful as part of an assessment of fitness to drive. This suggestion needs to be validated by research investigating whether these tests predict crash risk in the same way that UFOV does.In the interests of identifying older drivers at higher risk of crashing, with a view to restricting their driving, fitness to drive tests require development and validation. One particular test that makes claim for inclusion in any battery of fitness to drive tests is the Useful Field of View test (UFOV)1. UFOV subtests appear to depend heavily on speed of visual processing, and on indexing crowding in peripheral vision. However, UFOV is a proprietary instrument and other custom software is available for measuring speed of visual processing and crowding in peripheral vision. Sixty participants aged over 60 completed UFOV. They also completed inspection time (IT), a measure of speed of visual processing, and crowding across the visual field (CAVF), a measure indexing effects of strength of crowding in peripheral vision. Thus, the current study compared performance on UFOV, inspection time (IT) and crowding across the visual field (CAVF). The main outcomes here were that the IT and CAVF measures had high test-retest reliability over a period of about one week and did not exhibit statistically significant practice effects. By way of contrast, although UFOV measures were also highly reliable, two of three UFOV measures, Divided Attention and Selective Attention, showed practice effects; the third measure, Processing Speed, showed severe range restriction in the current sample of healthy older adults. Correlations between CAVF, IT and UFOV Selective Attention were very high. These outcomes suggests that IT and CAVF together may well prove appropriate and useful as part of an assessment of fitness to drive. This suggestion needs to be validated by research investigating whether these tests predict crash risk in the same way that UFOV does.