Two players, in turn, called out a pair of numbers
(from one to thirty), which appeared on a three-sided
wedge on a game board. If the prizes (or information
such as "forfeit one gift" or "take one gift") matched,
the player was credited with the prize. The third part
of the wedge was shown when a match was made, and
revealed two portions of a slowly building rebus puzzle.
The player was given a chance to guess the answer and
if correct, they won the game and all prizes credited
to them. If not, they called out two more numbers and
tried to make another match. When the player failed to
make a match, the turn then went to the opposing player.
The winning player continued to play against other
challengers until defeated or winning twenty games.
Concentration was NBC's longest running game show.
In addition to its fourteen year daytime run (the show
ran in syndication the last six years), there were
also two primetime versions, a four week run in 1958
with host Jack Barry and a five month run
in 1961 with host Hugh Downs.