Anakin Skywalker during his Eyes of the Force testing

Eyes of the Force was a regimen that trained a Force-sensitive to sense images that can't be normally seen by reading the surface thoughts of others. During this regimen, an assistant held a two-dimensional image viewer so the user can't see the images being displayed on the screen. As the image viewer cycled through different images of common objects, the prospective trainee must read the surface thoughts of the assistant to determine what images were being displayed on the screen at the time. Mace Windu used this method to test a young Anakin Skywalker when he was brought to the Jedi Temple in 32 BBY.