I learned in highschool that even thought we have a wide view, we only observe a tiny fraction of that view through our eyes. So at any instant we are not really looking at all the objects infront of us, this is why we need to individually focus at each object at a time.

Question: What is the % of view that is in focus at any instant of time compared to the full view we observe thorough our eyes?


1 Answer 1


What you learned in high school isn't exactly true (or is misremembered). Human eyes get visual input across about 120 degrees of visual angle, and some herbivore mammals see near 360 degrees total between their two eyes.

However, the resolution is not constant. The fovea is an area of high-density receptors in the retina. When you look at something specific, you are directing light from that area of the visual field to the fovea. The fovea is limited to about 2 degrees of visual angle.

Additionally, your attention is often limited to a small section of the visual field. When viewing a scene, your eyes will naturally make saccades to bring various points into high acuity vision to get a good sense of the entire scene, but you are still seeing all the surrounding area, even if you aren't paying much attention to it. Importantly, you are still sensitive to surprising stimuli (especially those that are high-contrast or moving) in those areas that might cause you to redirect your attention, otherwise you would be very easy to sneak up on.

  • $\begingroup$ yes its the 2 degrees of visual angle that i remember now. So still a small fraction around 1/60th area of the whole view is in focus at any one time. You mentioned that the "attention" is limited to small section of visual field, can we say that its limited to 1/60th of the visual field? So to say some entity is in attention is in the fovea as we are focusing on it? $\endgroup$
    – gfdsal
    Aug 18, 2020 at 22:57
  • $\begingroup$ @gfdsal It's roughly spherical so more like 2^2/120^2. For attention it's a bit complicated and there are no sharp boundaries, but you could say it's on a similar spatial scale. $\endgroup$
    – Bryan Krause
    Aug 18, 2020 at 23:24
  • $\begingroup$ note the rest of the eye is still used but it is more to detect change (usually movement) , once something changes your attention and focus move to that point. you focus is constantly moving around to what you think is important, so although you only get a god image of about 2% your brain can reconstruct a much larger image. $\endgroup$
    – John
    Aug 19, 2020 at 2:50
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    $\begingroup$ To be precise, I think the answer (and the question) are mixing focus and resolution. For example, a myopic eye wouldn't focus the image, regardless of the fovea resolution. Focus would depend on the quality of the lens, not the sensor. $\endgroup$
    – jinawee
    Aug 19, 2020 at 7:50
  • $\begingroup$ @jinawee Did you notice I didn't use the word focus at all? OP used that word, but it is clear from context that they are referring to the target of gaze (which is also what a properly working eye focuses on), rather than the specific processes that go on in focusing. $\endgroup$
    – Bryan Krause
    Aug 19, 2020 at 14:36

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