Young children's habit of talking to imaginary friends can spur the development of an inner dialogue that they can use to talk themselves through challenging tasks now and later as adults, a study in the November issue of the Journal of Experimental Child Psychology suggests.

Children often talk out loud while playing until about age 7, when their outbursts and mutterings become quieter and more internalized, research has shown. This private speech, or verbalized thought, has been shown to improve children's performance on...