A Relationship between Tolerance of Blur and Personality

It is assumed that most people are bothered by blur. However, some may tolerate higher levels of blur than others, such as those with reduced vision1 and, perhaps, older individuals2 (Kline DW, et al. IOVS 2006;47:ARVO E-Abstract 1203). A common clinical observation is that patients exhibit various levels of tolerance of degraded image quality induced by vision corrective devices. We investigated whether these individual differences in tolerance of blur are related to personality. In the late 1940s it was noted that personality factors may be implicated when large individual differences in the results of psychophysical measurements are observed.3,4 Responses were seen to reflect the interplay between perception and individual cognitive and motivational characteristics. More generally, it was believed that individual differences in personality characteristics could influence perceptions of the social and physical environment.5–7 Contemporary personality research has demonstrated that personality traits exhibit both behavioral and perceptual properties. For example, across several studies, hostile individuals not only exhibited anger and aggressive behavior, but they also perceived ambiguous situations and random individuals much more negatively than did less hostile individuals.8,9 Despite the long-held theoretical supposition that personality and perception are meaningfully related, there is a paucity of research on the relationship between personality and visual perception. Over 40 years ago, it was proposed that personality traits correlate with refractive errors.10 Since then, several research groups have investigated this association with inconclusive results.11–16 Other possible relationships between personality and vision that have been investigated include choice of refractive correction,17–21 keratoconus,22–25 strabismus,26 binocular rivalry,27 eye movements,28–30 and visual stress.31 However, we know of no studies of the association of personality and the perception, or tolerance, of blur. Individuals with presbyopia who wear progressive-addition lenses report limits of clear and comfortable vision beyond those expected from blur-detection thresholds,32 suggesting tolerance of the induced blur. Recently, Atchison et al.33 and Ciuffreda et al.34 proposed new operational definitions of perception of blur, ranging from least (just-noticeable33 or detectable34 blur, which is equivalent to depth of focus35,36) to unacceptable (just-objectionable33 or bothersome34 blur). These measures of unacceptable blur may be more relevant to the evaluation of visual function than are blur-detection thresholds (depth of focus). The linear relationship between blur thresholds and letter sizes33,34 suggests that these judgments were based on the legibility of the letters. The comparable results of the two studies show that such blur tolerance measures can be made reliably in different samples. Neither of those studies reported individual differences in blur tolerance, which would be expected if there is a relationship between personality and blur tolerance. In our study, we measured blur tolerance as the difference between the just-noticeable and the just-objectionable levels of blur. Blurred vision is a suboptimal condition for humans and may be a sign of maladaptive functioning if allowed to persist. We hypothesized that psychologically high-functioning people do not tolerate blur well, whereas low-functioning people may tolerate blur to their detriment because they lack the psychological resources to positively change their environments.