Abstract
Visual perception and imagery are known to use the same resources in the visual cortex (Kosslyn et al., 1995). The finding that the size of V1 predicts the amount of illusion (Schwarzkopf et al., 2010), which is part of visual perception, led us to postulate that the size of visual cortex is related to the vividness of visual imagery. In this study, the size of visual cortex was indirectly measured by vernier acuity and the size of the blind spot. Note that vernier acuity indicates the degree of cortical magnification (Duncan & Boynton, 2003) and the size of the blind spot reflects the size of optic nerve (Jonas et al., 1991). Vividness of imagery was measured by the vividness of visual imagery questionnaire (VVIQ; Marks, 1973). Results showed that the two indirect measurements were significantly correlated (r=.273, p=.019), and that VVIQ scores were also significantly correlated with vernier acuity (r=.295, p=.011) and also with the size of the blind spot (r=.384, p=.001). These correlations indicate that vivid imagers (having lower VVIQ scores) are related to smaller size of visual cortex, suggested by the indirect measures. VVIQ-defined vivid imagers can be characterized by their faster generations of visual imagery as reported by D'Angiulli and Reeves (2002). To test this hypothesis, we measured the time taken to generate the image of each question in VVIQ for 39 out of 83 participants. Results showed that as generated images became more vivid, the time taken to generate them was shorter (r=.445, p=.005). This positive relationship was further supported by the significant result that the number of participants who showed positive correlations between the two variables was more than that of those who did not (x²(1)=39, p<.001). In sum, vivid imagery was correlated with faster imagery, which might have been enabled by smaller visual cortex.
Meeting abstract presented at VSS 2014