Archive for August 16th, 2021

August 16, 2021

About perception

by Neil Rickert

In a recent post, I suggested that perception is an important part of perception. One commenter disagreed, and wrote “Perception is simply raw sensory impressions”. That’s actually a common view. A lot of the literature on empiricism suggests that it starts with impressions.

I’m actually not quite sure what people mean by “impression” when they make such statements. I expect that they are probably thinking of conscious impressions — something that we can think about. However, it seems to me that much of perception is prior to conscious experience.

The expression “raw sensory impression” could also mean the forming of an image (in the visual case). I’m doubtful that we form images. I cannot see any good reason why an ability to form images would evolve, because it is hard to see much benefit from having such an ability. What really matters to an organism, is getting useful information about the immediate environment. So my own thinking about perception has tended to emphasize that information problem.


One of the problems for visual perception, is that we are moving. We move our bodies. We also move our heads relative to our bodies. And our eyes move (in saccades) relative to the position of our heads.

If you have ever tried taking a picture with a moving camera, you probably know that this can result in a blurry picture. A high shutter speed can reduce the problem. However, the response of retinal sensory cells is slower than high speed shutters, so that method is not available to the visual system.

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