Asklemmy

The analogy works to a certain extent, with one lopsided difference between active listening and active viewing. With hearing, you could theoretically pay attention to one voice emanating from any direction, without repositioning yourself. You probably would turn towards the voice to optimize clarity, but it's not a requirement.

With active viewing, you have to point your eyes directly at the item of interest. That six degree area of visual focus corresponds with visual receptor cells densely packed in one spot on the retina called the macula. The density of cone receptors falls off the further away you get from the macula.

Think of following that one conversation in a crowd, but with a directional microphone. That would give some sense of the manual activity that goes along with vision, to maintain reliable and current information about the visual environment.