By A bit of all-too-human deviousness was also involved in Deep Blue’s win. IBM’s coders, it was later revealed, programmed the computer to display erratic behavior — delaying certain moves, for instance, and rushing others — in an attempt to unsettle Kasparov. Computers may be innocents, but that doesn’t mean their programmers are.
From Nick Carr’s review of Garry Kasparov’s new book Deep Thinking which is about Kasparov’s historic chess match against the IBM supercomputer Deep Blue.