According to the authors, the IllusionWorks site is, "the most comprehensive collection of optical and sensory illusions on the world-wide web." After spending a few hours on their site (and some others) I think I must agree. There are so many illusions, explanations, demonstrations, projects, and interactive puzzles (and that is just a partial list of what they offer), that I had to force myself to leave or I would have spent days exploring everything. Plus, you can choose to see introductory level explanations of the illusions or advanced level explanations. Of course, there are some drawbacks. First, you will need some plug-ins (e.g., shockwave), and a browser that is both frames and java-enabled to see everything. But even if you can't see everything, the site is still packed and worthwhile. If you want a stripped down version that has just some of the more popular illusions that can be seen without pug-ins check out the Gallery of Visual Illusions and SandlotScience.com (links below).
2. The Exploratorium - Online Exhibits
This is probably the most sophisticated and elegant site of the bunch. It includes many classic illusions that are really enhanced by modern technology, such as shockwave. This is the good news. It is also the bad news. If you don't have a fairly new browser (Netscape 3 or later; Internet Explorer 4) with the Shockwave plug-in, you won't be able to enjoy many of the experiments, demonstrations, and illusions. If you have these tools (or can download them), it is worth a visit to this site. The technology really makes the visit interesting and is an interactive delight. I enjoyed the "make a home run" interactive demonstration myself, but look around; there are things that almost everyone can find useful and fun.
3. Play Sensation and Perception Jeopardy
If you want to test your knowledge of Sensation and Perception, give this site a try. It begins with a Jeopardy-like board of categories and values. Just pick a category and a value you want to play for, and a question will appear. When you think you know the answer, click the "Answer" button and you'll see the right answer. The questions are decent (not too tricky) and wordy fairly well. However, it lacks some interactivity - you don't actually type in your responses or get a score as you play the game. Of course you can keep score yourself, but it would be nicer if it all happened online (so I'm picky, what can I say). Regardless, once you have read the chapters and done some studying, it is a nice way to prepare for a test and see where you stand.
4. Magic Eye
Created and maintained by Dr. Marc Grossman and Rachel Cooper, this site has some of the same illusions as the other sites on this list, but it also offers some unique information about 3D vision - what it is, how it works, and why some people can't see in 3D. This information, while it may not seem so relevant at first, ties in nicely to the sensation and perception sections you may cover in your Introductory Psychology class.
5. The Soundry
The Soundry is a site about sound and how the human auditory system works. This site is impressive for several reasons. First, the site was created by a couple of high school students (yes, I said high school students) for a web design contest sponsored by ThinkQuest. The site won the overall site design category and, we must say, deserves the award. The Soundry includes some wonderful animations and images of the auditory system. For example, you can go to The Ear section and get a guided visual and text tour of the ear. Want a closer look at any part of the ear, just click on that part, and you will get a description of that part and its function. Plus, you can then click the "where am I" link and you will get a pop up window showing you exactly what part of the ear you are dealing with relative to the rest of the ear (very much like one of those directories in a shopping mall). There are also sections on the physics of hearing that include very educational sections and some little game-like applets that help understand hearing a bit more. There is one drawback - since this site is currently hosted on the ThinkQuest site as the winner of a contest, it is hard to say how long it will be there. AlleyDog.com tried to stay current, but it may not be there for long (if you get there and it is no longer available, please email us and let us know).
You can also check out these other resources: