On the joint effect of endogenous spatial attention and defocus blur on acuity: attentional limit to the resolving power of the eye

Defocus blur and spatial attention both act on our ability to see clearly over time. However, it is currently unknown how these two factors interact because studies on acuity resolution only focused on the separate effects of attention and defocus blurs. In this study, resolution acuity was measured along the diagonal 135{degrees}/315{degrees} with horizontal, at 8{degrees} eccentricity for clear and blur Landolt C images under various manipulations of covert endogenous attention. We observe that attention not just improves the resolution of clear stimuli, but also modulates the resolution of defocused stimuli for compensating the loss of resolution caused by retinal blur. Our results show, however, that as the degree of attention decreases, the differences between clear and blurred images largely diminish, thus limiting the benefit of an image quality enhancement. It also appeared that attention tends to enhance the resolution of clear images more than blurred targets, suggesting potential variations in the gain of vision correction with the level of attention. This demonstrates that the interaction between spatial attention and focus plays a role in the way we see things. In view of these findings, the development of adaptive (neuro-optical) interventions, which adjust the eyes focus to attention, may hold promise. Significance statementVisual technologies are now attaining a degree of extreme sophistication and diversity, which allows more comprehensive, but often complex manipulations of the optical image formed onto the back of the eye. It is therefore an enigma how those fine and immersive manipulations of the sensory environment are integrated in the brain. In this study, we show that the resolving power of the eye can depend complexly on the interaction between spatial attention and focus. This discovery suggests that perception might be advantageously guided by technologies tailoring optical focus to individual attentional patterns. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=116 SRC="FIGDIR/small/266700v2_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@de73b7org.highwire.dtl.DTLVardef@7ef3d3org.highwire.dtl.DTLVardef@b9a80dorg.highwire.dtl.DTLVardef@c8201e_HPS_FORMAT_FIGEXP M_FIG C_FIG Proposed neuro-optical mechanism of transformation of stimulus by spatial attention and blur.