Focus cues refer to the visual and depth cues that our eyes and brain use to perceive the relative distance and depth of objects in our environment. These cues include binocular cues (such as retinal disparity and convergence), monocular cues (such as size, texture gradient, and linear perspective), and accommodation cues (changes in the lens shape of the eye). Understanding how focus cues work together to create our perception of depth and distance is important in fields such as psychology, neuroscience, and virtual reality technology. Research in this area often focuses on how different types of focus cues interact, how they are processed by the brain, and how they can be manipulated to create more realistic visual experiences.