The targets used for these tests are the standard ESP Cards (sometimes called Zener Cards) as used by the parapsychologist J.B. Rhine in his classic studies of Extrasensory Perception. These show five different symbols.
In this test, a card is selected on each trial by a pseudo-random computer algorithm. There is no discernible pattern to the sequence of cards.
Although equi-probable, the cards will generally differ in the overall frequency with which they are selected (in the same way that tossing a coin several times will not necessarily result in equal numbers of heads and tails).
You have to guess 25 cards, each of which is selected by the computer prior to your guess. The actual card will be shown after you click on your chosen symbol.
To show evidence of ESP, you need to score at least 10 correct guesses (hits). The chances of obtaining 10 or more hits by luck is less than 1 in 20.