Ask the Brains; October/November 2007; Scientific American Mind; by Gregory Hickok and Carol Padden, Mark A. W. Andrews; 1 Page(s)
Just like hearing people, deaf people can mentally rehearse a speech, mull over a conversation in their head or simply ramble internally about the day's happenings, all in the form of mental images of signs. To get a sense of what talking to yourself in sign language might be like, imagine waving good-bye or blowing a kiss--you are "talking to yourself" in gestures. Now imagine knowing a whole language of signs complete with grammar that would give you the capacity to converse with yourself internally about anything you like. Deaf people who use any of the world's sign languages certainly have this capacity and indeed talk to themselves regularly in signs just as hearing people talk to themselves in speech.
Brain-imaging experiments have mapped the major circuits involved in what is often referred to as inner speech (or in the case of sign language, inner sign). A study by one of us (Hickok), for example, monitored neural activity in the brains of deaf signers who were asked to rehearse sets of signs mentally. Inner signing activated a network of regions that are known to be involved in the overt production of sign language, including areas of the frontal, parietal and temporal lobes. Some of these same regions, particularly those in the left frontal lobe, are also involved in the inner speech of hearing people. These frontal regions have long been associated specifically with speech functions, but their involvement in sign language and in complex motor behaviors beyond language has suggested a more general function, such as the selection or inhibition of complex action plans.