Memory

Concentration (also known as Memory and Brain Food) is a recurring memory challenge that originated in, and has since reappeared in , and. The challenge is a version of the simple children's game of the same name.

Rules
Scattered in a challenge arena are numerous pairs of matching objects or symbols hidden under covers. One at a time, contestants will enter the field and uncover two items. If they match, they (or their tribe) scores a point. If the items do not match, they are recovered and the next contestant takes their turn. The first tribe/contestant to score a designated number of points, or the tribe/contestant with the most points when all covers have been unveiled wins the challenge.

Additional rules have appeared season to season, such as the inclusion of items that do not have a matching pair. In, tribes uncovered survival items, and could choose to forfeit a point in order to put the item into the reward pool for the winning tribe.

History
The challenge debuted in as Memory, where it was used for individual immunity. 18 pairs were in the field, and the highest score at the end of the game would win. Colby Donaldson won the challenge, receiving immunity.

In, the challenge was used as for tribal immunity. Tribes matched words and numbers on sandwich-boards, with the first tribe to score seven pairs (out of 13), winning. Moto continued their winning streak to take home immunity.

used the challenge for tribal reward under the name Brain Food. Tribes were permitted to forfeit a point in the challenge to place any matched item into the reward pool that would be taken home by the winner. Galu won the challenge, receiving the forfeited items and a sailing adventure.

The challenge was repurposed as a Duel in, with the first person to score five matching symbols winning the challenge. Matt Elrod beat Stephanie Valencia, permanently eliminating her from the game.