The Effect of Refractive Blur in the Vividness of Mental Imagery

BackgroundVisual mental imagery or "seeing with the minds eye" is an everyday phenomenon. Visual mental imagery and visual perception share common neural-networks. Hence deficits that affect the visual perception may also affect visual mental imagery. AimWe aimed to study the effect of refractive blur on the vividness of mental imagery. MethodsSubjects were recruited from volunteers and divided into two groups; individuals with refractive errors-Ametropes(AM), and individuals without refractive errors - Emmetropes(EM). After filling in the Verbalizer-Visualizer-Questionnaire (VVQ), the subjects were asked to perform a mental imagery task with and without refractive blur. The participants were asked to generate a mental image of a specific object initially with eyes closed, eyes open and then with refractive blur in random order, and then judge the vividness of the mental image on a Likert scale ranging from 1 (low vividness) to 5 (good vividness). The EM participants had to wear a + 2D spectacles to produce refractive blur. ResultsA total of 162 participants were recruited to the study. Of these 73 were EM and 89 were AM. Of the AM, 30 had additional astigmatism. The mean VVQ score was 64.9(11.2). The mean refractive error was 1.8(1.3)D. Following the mental imagery task, at baseline with eyes closed, 138 (85.5%)subjects had vivid mental imagery close to visual perception(Likert scale:5). With the opening of the eyes, the vividness dropped by at least 1 point in the Likert scale in 139(85.8%). With the introduction of refractive blur, 153(94.4%) subjects had a drop in the vividness of the image by at least 1 point and 22(13.6%) subjects by at least 2 points. ConclusionIntroduction of refractory blur results in the reduction of the vividness of mental imagery.