This is Your Brain On Awesome Thoughts on the world from a student of the mind

21Feb/11

Motion, identity, and optical illusions: the case of silencing

Everybody loves a good visual illusion, and I'm happy to say that Harvard psychologists have recently discovered yet another mind-bender to add to my wonder of the confusing world that is our visual system.

It's called "silencing", and describes an effect by which we fail to recognize changes in visual objects that are moving with respect to our eyes.

The researchers showed subjects a visual scene in that was composed of a circle of dots that constantly changed color.  The change in color is quite obvious, but an amazing thing happens when you set the wheel in motion.  Once the circle of dots start rotating, they appear to stop shifting color.  Stop the wheel, and they immediately revert back to their dynamic former selves.

Such a finding points to the importance of motion in our visual system, a component of vision that seems to have a particular importance in our evolutionary past.

For many decades now scientists have suggested that, broadly speaking, there are two different pathways when interpreting the visual information entering your eyes.  One is considered the "what" pathway, and deals mostly with specific object features and color.  The other has been coined the "where" pathway, and tends to respond to location, motion, and more coarse features of objects.

With the discovery of "silencing", we've got yet another example of how one of these pathways might effect the other.  Set the wheel in motion, and you start losing the ability to distinguish the finer features of the dots.  Why this happens is anybody's guess, but it's an important step in understanding the intricacies of our visual system.

check out Harvard's VisionLab for more videos and demonstrations

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  1. That’s a good idea! How’s this?


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