IBM's Watson 'Our New Computer Overlord' in 'Jeopardy'

In his Final Jeopardy answer, Ken Jennings wrote, "I, for one, welcome our new computer overlords," as he conceded victory to IBM's Watson.

The humans redeemed themselves in the second game of the man vs. machine "Jeopardy" tournament, after the previous game's debacle, but it wasn't enough. The best "Jeopardy" player is now a computer named Watson.

Watson didn't dominate the Feb. 16 game as thoroughly as it had on the previous night, with Ken Jennings and Brad Rutter repeatedly beating Watson on the buzzer. Although Watson started out strong, Jennings rallied and got some momentum, taking the lead away from Watson. At the end of the first round, Jennings led the game with $8,600 to Watson's $4,800 and Rutter's $2,400. Jennings continued to perform in Double Jeopardy, with $17,000 to Watson's $15,073 late in the game.

And then Watson found both Daily Doubles to close the gap and finish the round with a $5,240 lead over Jennings. After Final Jeopardy, which they all answered correctly, the final score was $44,131 for Watson, $19,200 for Jennings and $11,200 for Rutter.

Game one wasn't even close, with Watson finding both Daily Doubles and running away with $35,734, while Rutter had $10,400 and Jennings $4,800. The total score for the tournament cemented Watson's victory: Watson ended up with $77,147, Jennings with $24,000 and Rutter $21,600.

"What have I learned over the past two days? One, Watson is fast, knows a lot of stuff and can really dominate a match," "Jeopardy" host Alex Trebek said at the beginning of the game.

However, some of the categories clearly gave Watson some difficulties. It didn't even buzz in on some of them. Watson totally misunderstood the "Also on Your Computer Keys" category, and while it figured out the answers in the "Actors Who Direct" category, it wasn't fast enough to buzz in ahead of the humans.

Throughout the match, Watson's confidence levels were frequently drastically low, a dramatic contrast to the first game. On several of the clues, especially in computer keys category in round one and the clothing category in Double Jeopardy, Watson's confidence levels hovered around 20 percent or less. While its buzz threshold can change depending on the game state, Watson by default does not buzz in unless it is at least 50 percent confident in the answer, according to IBM researcher Jon Lenchner.

There were also several instances when the correct answer happened to be the third item on its list of possible answers. For the Daily Double clue about a 1959 book, Watson inexplicably answered, "Dorothy Parker," which it had 14 percent confidence, while the correct answer, "Elements of Style," had a mere 10 percent confidence.

"Watson is capable of some weird wagers," Trebek said.

On its Daily Doubles, it wagered $2,127 and $367, respectively. Watson can precisely calculate its confidence level for the category based on what it has figured out about the category, as well as a "game state evaluator" model to estimate its chances of winning based on the other players' scores, number of remaining clues and value of remaining clues, according to IBM researcher Gerald Tesauro.

Watson departed from its usual conservative bets during Final Jeopardy, wagering $17,973 on the "19th Century Novelists" category. And Jennings, who had joked about needing to either unplug Watson or bet it all during a Daily Double earlier in the game, wagered only $1,000.