Vision Research

 

Let’s take a simple and entertaining example to illustrate the meaning of “uncertainty” in the field of vision.  You have probably mused on and been amused by the famous Necker cube, shown in the accompanying figure.

 

If you look intensely at the cube for a few seconds, it will tend to “flip”.  That is, the near face of the cube changes place with the far face;  the cube switches orientation from protruding into the screen to protruding out of the screen. 

 

The Schroeder reversing staircase is another example of the multistable figure.  After a few moments, most people experience the staircase inverting, or turning upside down. 

 

We can understand why these figures change their apparent orientation with reference to our leitmotif: perception as reduction in uncertainty (please refer to Overview or Auditory Research).  As the process of perceiving (or “sensating”) proceeds, uncertainty about the nature of the perceived object decreases.  When uncertainty reaches zero, the perception (or sensating) process terminates.  Stated another way, It is not possible to perceive a certainty.

 

As we continue to observe the Necker cube or Schroeder staircase, we become more and more certain about the nature of the object we are viewing.  When we have become perfectly certain, our image of the ingoing cube or upgoing staircase vanishes (we cannot perceive a certainty), and is replaced by the alternative image: the outgoing cube or the downgoing staircase. As that object becomes nearly certain to our brains, the orientation shifts again. 

       

You can use this knowledge about the nature of the sensating process, to make a prediction.  Suppose that an image – of any object or scene – is fixed in a stable position on the retina, which is the light- sensitive portion of the eye, similar to the film in a camera. That is, the image occupies exactly the same region on the back of the eye, so that no matter how you might move, you cannot divest yourself of this image.  The question is:  What happens to your perception of that image?  You can carry out a simple version of this experiment by staring intently at a single small black circle (about one centimeter in diameter) drawn on a piece of paper, trying very hard not to blink.  Can you predict what will happen to your perception of that black circle ?  After thinking about the problem for a few minutes, compare your thoughts with our own by clicking on the Ahahh!  button.

 

Ahaa!