As babies, we first learn to identify faces, then objects, quickly becoming expert and taking joy in the accomplishment. Understanding motion is one of the next key challenges in making sense of the visual environment, both the motion of objects and our own motion, which involves great cognitive complexity. Considering visual illusions can help us to better understand both strengths and weakness of our visual system. For example, perspective plays strongly into our visual understanding, but is easily distorted. Temporal illusions are also useful to understand, since vision is so closely tied into our sense of time and reality. Differences in time perception have been observed in natural versus urban environments, and may be connected to our level of boredom or engagement with the visual environment,
We also increasingly notice the strengths and weaknesses of our visual system as we start to age. After age forty, most people need corrective lenses to help with presbyopia. Other forms of low vison become increasingly common with aging, and are often not well understood by younger people who design physical environments. Decline of visual function makes older people even more sensitive to visual conditions, and in need of stronger circadian stimulus.