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M.L. Lawson, S.G. Crewther, B. Junghans, D.P. Crewther; The Role of Accommodation in Shifting Between Global and Local Attention . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4098.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The capacity to process either the overall form of an image (global attention) or to focus on the component parts of the scene (local attention) has been extensively studied using psychophysical and neuroimaging techniques. Shifts in attention accompanying a change from local to global information processing are faster than those from global to local. Such an effect may be related to the physiological time required to focus on smaller, more local information and subsequent need to accommodate. Thus, the aim of the current experiment was to examine whether accommodation plays a role in the shifting of attention between global and local visual information. Method:10 adult participants aged 19-27 (M=20.7) viewed sequences of complex global local letter figures and were asked to identify either the global or local aspect of a red target letter, and subsequently detect the presence or absence of a probe letter (X) presented at the opposite attentional level. Refraction was measured at the time of target and probe presentation using a Canon R1 auto-refractor. Results: Change in refraction across the two measurements (target – probe) for conditions requiring a shift from global to local (GL) and in the reverse direction (LG) was calculated. A significant change in refraction of –0.127 D was observed only in the GL condition. Conclusion: The presence of a physiological shift in accommodation in GL conditions may well explain previous evidence describing longer reaction times in GL conditions compared with LG conditions. Further research is required to examine whether this change is an active mechanism, or a consequence of the shifting in accommodation needed to handle changes in stimulus size between global and local information in the same scene. The impact of processes such as convergence need to be examined to further clarify the role of accommodation in shifting attention.
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