<P> From the premiere of the original Jeopardy! until the end of the first season of the current syndicated series, contestants were allowed to ring - in as soon as the clue was revealed . Since September 1985, contestants are required to wait until the clue is read before ringing - in . To accommodate the rule change, lights were added to the game board (unseen by home viewers) to signify when it is permissible for contestants to signal; attempting to signal before the light goes on locks the contestant out for half of a second . The change was made to allow the home audience to play along with the show more easily and to keep an extremely fast contestant from potentially dominating the game . In pre-1985 episodes, a buzzer would sound when a contestant signaled; according to Trebek, the buzzer was eliminated because it was "distracting to the viewers" and sometimes presented a problem when contestants rang in while Trebek was still reading the clue . Contestants who are visually impaired or blind are given a card with the category names printed in Braille before each round begins, and an audible tone is played after the clue has been read aloud . </P> <P> The second round, Double Jeopardy!, features six new categories of clues . Clue values are doubled from the Jeopardy! round (except in Super Jeopardy!, where Double Jeopardy! values ranged from 500 to 2,500 points). The contestant with the least amount of money at the end of the Jeopardy! round makes the first selection in Double Jeopardy!; if there is a tie, the tied contestant standing at the leftmost lectern selects first . </P> <P> A "Daily Double" is hidden behind one clue in the Jeopardy! round, and behind two in Double Jeopardy! The name and inspiration were taken from a horse racing term . Only the contestant who uncovers a Daily Double may respond to that clue and need not use his / her signaling device to do so . Before the clue is revealed, the contestant must declare a wager, from a minimum of $5 to a maximum of his / her entire score (known as a "true Daily Double") or the highest clue value available in the round, whichever is greater . A correct response adds the value of the wager to the contestant's score, while an incorrect response deducts it . Whether or not the contestant responds correctly, he or she maintains control of the board . </P> <P> During the Jeopardy! round, except in response to the Daily Double clue, contestants are not penalized for forgetting to phrase their response in the form of a question, although the host will remind contestants to watch their phrasing in future responses . In the Double Jeopardy! round and in the Daily Double in the Jeopardy! round, the phrasing rule is followed more strictly, with a response not phrased in the form of a question counting as wrong if it is not re-phrased before the host or judges make a ruling . If it is determined that a previous response was wrongly ruled to be correct or incorrect, the scores are adjusted at the first available opportunity . If, after a game is over, a ruling change is made that would have significantly altered the outcome of the game, the affected contestant (s) are invited back to compete on a future show . </P>

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