Page "Stolen base" Paragraph 2

If the defense makes no attempt to put the baserunner out ( for example, if the catcher doesn't even look his way ), the play is scored as defensive indifference ( also called fielder's indifference ), and no stolen base is credited to the runner.

Defensive indifference is generally only scored instead of a stolen base when the game is in a late inning and the team with the stealing baserunner is down by more than one run.

MLB Rule 10. 07 ( g ) covers defensive indifference.