"Concentration" premiered on NBC on August 25, 1958, at 11:30 A.M. Eastern time.
A mechanical game board was divided into 30 numbered squares, most hiding the names of prizes. Two contestants called out numbers to try to match two squares with the same prize behind them. If the contestant made a match, they would take possession of that prize, and the squares they had picked spun around to reveal part of a pictorial rebus. The first contestant to solve the rebus won the prizes they had matched.
Some of the prizes listed were gag prizes (similar to the zonk prizes on "Let's Make a Deal" but existing in name only). Also hiding behind the board were squares reading "Take," "Give," and "Wild." The wild card meant an automatic match with a prize, and three parts of the rebus being revealed. "Take" gave the contestant the opportunity to steal a prize from their opponent's list, while "Give" forced the contestant to pass one of their prizes to their opponent, which meant the gag prizes came in handy.
Although the format sounded simple, "Concentration" ended up as the longest-running game show in NBC history. Hugh Downs was the host for the first 11 years; at the beginning of 1969, when he finally got tired of hosting both "Concentration" and the "Today" show every morning, announcer Bob Clayton became the host. He was replaced by Ed McMahon a few months later, and then returned as host six months after that, staying until the show went off NBC on March 23, 1973.
Jack Barry also hosted a weekly prime time version in 1958 that was a temporary emergency replacement for "Twenty-One"; a prime time version also aired in 1961 with Hugh Downs doing double duty as host.
After NBC canceled "Concentration," Mark Goodson and Bill Todman leased the rights to the format and produced a syndicated version with host Jack Narz, which lasted from the fall of 1973 until 1978. A bonus round was added in which the winning contestant had to quickly solve two rebuses in order to win a car.
"Concentration" returned to NBC's daytime schedule on May 4, 1987, now with the title "Classic Concentration" and host Alex Trebek. There were now only 25 squares on the computer-generated board, and the gag prizes and "Give" cards were gone.
In the bonus round on this version, the winning contestant could win one of eight cars parked on the set by making seven matches on a board of 15 squares, winning the last car matched. The allotted amount of time began at 35 seconds and increased by five seconds every time the game was lost.
A couple of years after "Classic Concentration" premiered, it inexplicably gained a neon palm tree on the set, and Alex Trebek's wardrobe switched from suits to sweaters.
"Classic Concentration" last aired on NBC on the last day of 1993. Since NBC controls the rerun rights, it is unlikely old "Concentration" or "Classic Concentration" episodes will show up on Game Show Network in the near future.