Donald Hoffman

A Book Review by: Paul Harris, OD  

This was one of those books that caught my eye while perusing the shelves of my favorite bookstore one evening before dropping in to see the latest movie.  The title caught my eye and as I perused various sections of the book, I knew I had to have it. Right in the Preface statements like the following hooked me;

“Vision is not merely a matter of passive perception, it is an intelligent process of active construction.  What you see is, invariably, what you visual intelligence constructs.” 

Hoffman works in the field of visual perception.  Research on how we perceive the things we do when we look at optical illusions has led to the elucidation of a series of general principles of vision.  He builds these from the ground up throughout the book with each section building a prior section.  He states that the fundamental problem of vision is that;

“The image at the eye has countless possible interpretations.  For instance, each child constructs a visual world with three spatial dimensions – height, width, and depth.  But an image has just two dimensions—heights and width.  It follows that, for a given image, there are countless 3D worlds that a child could construct, each of which is compatible with the image in this sense: If you view that 3D world from the right place, then you will obtain the same image.”

Hoffmann states, “The fundamental role of visual rules: You construct visual worlds form ambiguous images in conformance to visual rules.”  One such rule is the rule of generic views that states, “Construct only those visual worlds for which the image is a stable (i.e., generic) view.”  Some examples are: always interpret a straight line in an image as a straight line in 3D, or if the tips of two lines coincide in an image, then always interpret them as coinciding in 3D.   Throughout the book, the author builds and builds until 35 rules have been stated, explained and examples or demonstrations given to help the reader understand that which he is talking about. 

I will admit that I was unable to see in some of the illusions the alternate view.  I know you are saying…. Embedded!  OK.  Get the book, work through it and let’s see how you do. It will be worth the time!

Examples of the first 10 Rules of Visual Intelligence: 

Premise: The fundamental role of visual rules is that you construct visual worlds from ambiguous images in conformance to visual rules.  The Rule of generic views states that you construct only those visual worlds for which the image is a stable (i.e., generic) view. 

1.    Always interpret a straight line in an image as a straight line in 3D.

2.    If the tips of two lines coincide in an image, then always interpret them as coinciding in 3D.

3.    Always interpret lines collinear in an image as collinear in 3D.

4.    Interpret elements nearby in an image as nearby in 3D.

5.    Always interpret a curve that is smooth in an image as smooth in 3D.

6.    Where possible, interpret a curve in an image as the rim of a surface in 3D.

7.    Where possible, interpret a T-junction in an image as a point where the full rim conceals itself: the cap conceals the stem.

8.    Interpret each convex point on a bound as a convex point on a rim.

9.    Interpret each concave point on a bound as a saddle point on a rim.

10. Construct surfaces in 3D that are as smooth as possible.