This web book will be continuously developed and improved based on received feedback.   If you find errors or have suggestions for improvement, please don't hesitate to contact me, (the author) .   A word of caution: I have attempted to make the material in this web book as accurate as possible.   I am now a professor emeritus, which means that I have retired and am no longer academically involved  in research and teaching.  As time passes, various parts of this book may become obsolete.  As noted below I consider this web book to be supplementary to hard cover texts and strongly suggest that teachers and students do not use The Joy of Visual Perception as a stand-alone source of educational material.

The Joy of Visual Perception: A Web Book is not a book in the traditional sense. Most books are text supplemented by figures. This book is primarily figures and diagrams supplemented by text. As a consequence to use this book on the Web it is important to have graphics capabilities on your browser. 

Another difference between a web book and ordinary textbooks is that when on the web one can link to web pages that are available on the Internet. Such links will be found in Some Interesting Links**,  in Fun Things, as well as in various other parts of the book. I thank the scientists who made these websites available.  It was my intent to give appropriate attribution to all such websites.  If I had a "senior moment" and forgot to do so I'd appreciate being told.

When I started this web book my intention was to limit information primarily to non-medically related topics of visual perception.  Before I retired, I was a visual scientist,  not a physician.  Therefore I am not qualified to deal with most medical questions.  However, I frequently get asked medically related questions anyway.  So I have provided links, in this web book, to websites where medically qualified people have provided information.

The purpose of this book is to stimulate interest on a topic that has been a joy to me for more than 35 years. I hope that this "web book" will help you to learn about your sense of vision and encourage you to find out more about visual perception; perhaps to take courses on this subject at whatever educational institutions are available to you. Remember, the joy of learning is a joy forever.

Those of you who teach vision or perception courses may find this material useful as supplementary material to that which you otherwise assign to your students. One such book, if I may be permitted a bit of self advertising, is a new book I published with Dr. Robert Boynton entitled Human Color Vision, 2nd Edition. Although the main focus of this book is human color vision, many allied topics are covered, mainly because color vision does not exist in a vacuum.

One can move from one part of this book to another by using your left mouse button to click on specified words or objects. Screens that contain only text will have clickable words are color coded and underlined. Screens that contain graphics may have areas on which you can click. Look closely, for instructions on what objects are clickable. Often near the bottom of the screen you will see text on which you can click to move to another part of the book. Those of you who use browsers with Framing capabilities (e.g.. Netscape, version 2 and above, Internet Explorer version 3 and above) will see the Table of Contents in the left window if you start the book by looking at the cover. If you wish to move to a different location in the book by using the Table of Contents click on the appropriate link in the left window. If you only see one window then click on the Table of Contents link at the bottom of your screen.

There are times where you will want to backup just one screen and the clickable area on the figure does not do that. Your browser (Netscape,  Internet Explorer, etc) has a backup button (probably at the top of your screen) which is a backwards arrow. Click on it and you will go back one screen. If you have framing capability and see two windows then the back and forward buttons will not be activated. However, if you click your right mouse button you can click on forward and backward to move in either direction within a frame.

I must apologize for some long delays you will experience as figures are downloaded onto your computer. I could have made the graphic displays smaller by reducing their sizes and by making them simpler. Doing so would have detracted from their effectiveness. Besides, I am writing this web book, not for "today" but for "tomorrow." Each day it seems computers are made to be faster and have more memory. Consequently, what takes tens of seconds to download "today" will take a fraction of that time "tomorrow." The images in this book will appear on your screen faster if viewed from a CD.

Finally, it is a pleasure to acknowledge the partial support from the Natural Science and Engineering Research Council (NSERC) operating grant AO 295 which funded my research from 1968 to 1997. I am also grateful for the feedback I have received and continue to receive from many readers.

** Some links, such as this one which go beyond this book, will not work unless you are simultaneously connected to the internet.

Table of Contents
 Subject Index
 Table of Contents [When not using framtes]