Accommodation to polychromatic stimuli

A fundamental question in vision research is how the visual system creates and maintains a clear retinal image of the world. Understanding the oculomotor mechanisms involved in focusing the retinal image (termed accommodation) can yield insights into how clinical measurements of visual clarity translate to daily life, how to improve visual technologies like augmented reality, and how refractive errors such as myopia develop. It is known that accommodation mechanisms are sensitive to longitudinal chromatic aberration (LCA), which is the inability of the lens in the eye to bring all wavelengths of visible light into focus at once. This means that in polychromatic imagery, some wavelengths will always be out of focus. It is commonly assumed that the visual system prioritizes bringing middle wavelengths into focus on the retina, as it is known to do when light entering the eye is white and broadband. But it is unclear whether this holds true for natural, polychromatic light spectra, or what the mechanisms governing accommodation to such spectra are. The research in this Pathway to Independence proposal aims to quantitatively model the mechanisms supporting visual accommodation to complex natural imagery. During the mentored phase, the candidate proposes to probe color-sensitive accommodation mechanisms by measuring and modeling human accommodative responses to visual stimuli generated from a variety of skewed light spectra, particularly spectra with disproportionate energy at long or short wavelengths. During the independent phase, the candidate proposes to build principled statistical models relating accommodative behavior to the joint statistics of spectral power and depth in natural scenes. The candidate will then expand the scope of the research to study how spatial and color variations in natural scenes interact to impact accommodation. He will build models of accommodative mechanisms that account for the impact of these variations. Understanding how these mechanisms operate under natural conditions will improve our scientific understanding of vision and can support improved procedures for assessing and achieving visual clarity.