Which Direction is the Girl Spinning? By Cliff Young

         If we are to understand how we sometimes find ourselves falling for simple optical illusions, we need to understand how our minds work.  At the most basic level, we look upon things with our eyes, the image is then sent to the brain for translating.  It seems pretty basic but there are a lot of things that happen between seeing and understanding.  This is a brief summary of the process that allows us to fall for optical illusions. 

            The first thing we need to understand is that our brains like to make things as easy as possible.  According to Macknick and Martinez-Conde (2012), our brain is focused on survival, as such our brain will take shortcuts in perception that lead to optical illusions.  "Our heads don’t like to be confused and will take shortcuts to prevent that from happening" (pg. 47).  The easiest way to do that is by searching for patterns or assigning the incoming image to a predetermined category from prior experiences.  In Ian Stewart’s article Now You See It, Now You Don’t, he describes the neurons related to vision as a “clock” sensing images much like certain neurons in our ears may be attuned to specific tones.  Stewart says, “These signals compete for attention.  If the five o’clock signal is stronger than the seven o’clock one, for instance, the seven o’ clock one gets shut down” (2013, pg. 39).  When an image is viewed that equally activates both cells they compete with one another thus allowing our minds to be confused by the optical illusion.  

          A perfect example of this illusion is the “spinning dancer”, the silhouetted dancer seems to be rotating clockwise or counter clockwise.  What makes this illusion work is the fact that your neurons are competing against one another again, some of them are trying to fire for clockwise rotation while others are trying to fire for counter clockwise; this is what also allows our brain to switch from one image to the next.  A tip that may work for some of you is to look at the reflection/shadow of her foot, that seems to make the switch easier. 

            Obviously there is much more to take into account concerning illusionary effects, such as lighting, object relevance, color manipulation, or even one’s own personal experiences. This was just a look at one aspect of perception and illusion.  There are so many more variables involved, please, use your browser and experiment for yourself.

References

[GAMMS1981]. (2010, March 17). Optical illusion what way is the girl spinning??.[Video File]

          Retrieved from https://www.youtube.com/watch?v=rb1CZfUumDI.

Stewart, I. (2014). Now you see it, now you don't. New Statesman, 142(5190), 36-41.

Macknik, S. L., & Martinez-Conde, S. (2012). Mind-Warping visions 10 brain twisters compete to

          be the best illusion of 2011. Scientific American Mind, 22(6), 46-51.