My favorite optical illusion in golf in the approach to #1 at George Wright Golf Course in the city of Boston, MA. Its a  Donald Ross false front that extends 65 feet forward of the putting surface on this mid length par 4.
I have played this hole many times and this deceptive view causes one to under club by one or two clubs. As a golf course design/builder I am amazed at how the Ross foreman got the elevation just right to make the illusion work. A straight flat grade would not work, the builder tweaked the grade so it looks like a golf green.
Hey golf architecture fans, you should see this course,a Donald Ross design in the middle of the city of Boston, owned by the city. Its unadulturated Ross, without any ego driven green committee modifications. It was almost shut down a few years ago, now it is maintained by the city.

What about the third at Pasatiempo?

As to future play, it will be interesting, but, now that I know the bunker is behind the green, I'll not need be concerned about clearing a bunker that isn't there, and will err on the short, not the long side.

Patrick,

It seems that golfers and instructors always advise the golfer to "pick a target."   While you now "know" in your head that the bunker is behind the green, will you be able to pick an actual physical target, or will it be a matter of what you know trying to overcome what you see?    

I dont really expect an answer, but nonetheless ask the question because I think it may get at something fundamental to a good "optical illusion."   Even though a golfer may "know" that the view is an illusion, the view may still put the golfer in the uncomfortable position of having to execute a shot which is contrary to what his eyes see.   In this day of elevated tees and complete and total visibility, shots which mess with the golfer's perspective are a nice change.  

DMoriarty,

Because the pin is visible, it would become my aiming point, adjusted for extreme left or right positions.

Mike,

Thanks for the link to the picture, it's a neat looking hole.

But, what creates the optical illusion, and, is the photo taken at the golfers eye level ?

Patrick,
Pasatiempo #3 is a very deceptive hole with all sorts of illusions that make it seem much closer then it actually is. I actually almost think I shouldn't tell you what to expect there in hopes the you get to experience it the same way I did some 15-16 years ago, because Pasatiempo is loaded with all sorts of tricks and gadgets.

The entire site is located on a rather large side of a hill rolling downward. The actual fall is almost unnoticable from anywhere on the course, until you walk to the highest point--from the green @#11 to 12th tee. Where this figures at #3 is that the tee is near the lowest point of the course, and the green is situated quite uphill and you just really can't tell how far uphill. On first try, I think most will admit that it throws you for a loop to see yourself come-up rather short, figuring you had more then enough club. As in Carlyle's image, it doesn't look like a very long par three at all--IT IS.

William Flynn used optical illusions on greens that are quite sophisticated.  The 3rd hole at Rolling Green is one of the best examples I know.  I don't know how to post photographs but it can be seen in the My Home Course section.  It is a short downhill par 3.  There is a false front that adds to the perceptual miscue.  Only the first 1/5 of the green slopes back to front.  The remainder of the green has a slight slope front to back.  He used the angles of built up surrounds to further the impression that the green slopes back to front, that along with the general downward flow of the ground fools the eye to thinking that the green slopes severely back to front when it does not.  In fact, the ball runs from front right to back left, even with lofted irons when the greens run typically firm.

Yesterday at the Senior PA Amateur, I saw nearly every chip and put from the front of the green fly by the hole toward the back of the green.  Even after this miscue the players were short coming back to the hole.  The majority could not accept the fact that the seemingly uphill putt was faster than imagined.  They certainly were not convinced as the return putts that look fast but were not almost always came up well short.  Many players walk off that green with a dazed look on their face, it is that hard to read correctly.

Somehow, I missed this thread a month ago.  Great explanations Dunlop, and very good pictorial demonstration Eric.  Nothing to add, just good stuff guys!