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R. L. Woods, C. R. Colvin, F. A. Vera-Díaz, E. Peli; Personality and Tolerance of Blur. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1431.
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To determine if tolerance to dioptric spherical defocus is related to measures of personality. Clinical observations suggest that there is individual variability in tolerance to blur, and some populations (e.g. older people) may be more tolerant.
A computer-controlled Badal optometer was used to measure "just-noticeable blur" (depth of focus) and "objectionable blur" responses to positive lens defocus with 3.5mm, 4.5mm and natural pupils. Blur tolerance was defined as the difference between the just-noticeable and objectionable blur responses while viewing three 20/50 high-contrast letters. A personality battery consisting of the NEO-PI-R and the California Adult Q-sort (general measures of personality) and Perfectionism, Neuroticism, Highly Sensitive Person, Ego-Resiliency, Need for Structure, and Negative Emotionality scales (hypothesis driven measures) was administered using MediaLab software. One hundred normally-sighted subjects (median 21, range 18 to 46 years; median refractive error 0DS, range -5.87 to +2.75 DS) completed both aspects of the study.
Within-subject blur tolerance measures with the three pupil sizes were highly correlated (r = 0.88 to 0.92), implying good repeatability. There was a wide range of individual blur tolerance. The personality questionnaires exhibited acceptable reliability (Cronbach’s alpha = 0.67 to 0.91). Two perfectionism scales were significantly correlated with blur tolerance. The 15 questionnaire items most highly correlated with blur tolerance were factor analyzed and yielded two conceptually meaningful factors (both alphas = 0.76). The "low self confidence" and "disorganization" factors were positively correlated with blur tolerance (r = 0.38 and 0.36, respectively), and their composite correlated with blur tolerance (r = 0.46). In the personality literature, correlations of this magnitude are considered high.
These results provide initial evidence for a relationship between personality and blur tolerance. It appears that people who lack self-confidence may require strong evidence of blur before they have visual symptoms. Furthermore, disorganized people may tolerate blur because it is simply another manifestation of their untidy personal environments. Tolerance of blur may be related to perception of image quality. If so, personality may influence refractive error correction and other choices made when presented with degraded images.
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