The Magic Eye books, published in the 1990's, contained images which made use of depth perception to hide the outline of objects or words inside them. These images are autostereograms, though many people now use the term Magic Eye to refer to any autostereogram regardless of whether it was in the Magic eye series of books. There are a few types of autostereogram but only one lends itself as a good treasure hunt clue: the random-dot autostereogram which looks like random dots of colour until you shift the focus of your eyes to reveal a 3D shape or text floating within the randomness.
The example image below contains a shark. Remember that this is not a dot-to-dot: you are not trying to trace the outline of a shark - you must shift your focal distance so that the shark "appears".
This makes autostereograms a fantastic treasure hunt clue. A really easy way to create one is to use an online tool such as https://www.easystereogrambuilder.com which allows you to type your clue in its own generator and then download the image. You can can then show the image to the treasure hunters on a tablet or print it out.
On our online treasure hunt builder we have created 150 images containing hidden locations that you can use in your own treasure hunts. There are over 2500 other clues on there ready for you to use too!
In our experiments we discovered a few things that are worth considering when using an autostereogram in your treasure hunt:
- spelling out the clue in capital letters makes it much easier to read
- people who have issues with their eyes, and some children, struggle to perform the technique required to get the text to "appear" in the image
- the bigger the image/text, the better as they are much easier to read
- images less than 600px wide or smaller than A5 (when printed) will be difficult to see - this means that images on a phone are hard to use
We would always suggest having a backup clue in case the hunters cannot solve the autostereogram; this could be the same clue but as an anagram or some other format for the hunters to solve. This avoids the feeling of failure as they still have to work the answer out.