Do deaf people talk to themselves?
—Amelia Thomas, Rochester, N.Y.
Cognitive scientist Gregory Hickok of the University of California, Irvine, and linguist Carol Padden of the University of California, San Diego, respond:
ABSOLUTELY. 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.
But why do we talk to ourselves in any language? And why do we get the feeling that we can “hear” our own inner speech (or “see” inner signs)? One possibility is that inner speech is the voluntary use of a mechanism designed to monitor our own language output for error-correction purposes. The brain formulates a motor plan for an overt utterance, but before articulation it feeds that plan back into its language perception system, which can detect potential errors and send a correction signal if necessary. Because we have this kind of internal sensorimotor feedback loop, what is to stop us from using it to mentally rehearse a speech or to rehash a conversation? And because this internal loop has links back to our perceptual system, we have the sense that we are hearing (or for signs, seeing) our inner dialogue.
Do we have a dominant eye?
—Alexandros Syriopoulos, Athens, Greece
Mark A. W. Andrews, professor of physiology and director of the Independent Study Pathway at the Lake Erie College of Osteopathic Medicine, replies:
JUST AS MOST people have a dominant hand, almost everyone has a dominant eye, defined as the primary eye used when viewing an object at a distance. Approximately two thirds of the population is “right-eyed,” with most others being “left-eyed” and 2 to 4 percent having no discernible dominant eye. Most left-handed people are also left-eyed (and likewise for right-handers), but some individuals are cross-dominant.
Although scientists do not yet understand why we have a dominant eye, they have uncovered some interesting properties related to this phenomenon. Evidence suggests that one eye is better at sighting targets, and input from this eye may appear larger and clearer than that received from the other eye. The dominant eye also provides visual input to control movement and posture through subconscious pathways, and it has even been shown to inhibit input to the central nervous system from the opposite eye.
Knowledge and use of one’s dominant eye may be helpful in activities that require precise sighting—hunting, billiards and golf, for example. But although the idea has been proposed for years, there is no definitive evidence showing that cross-dominance is advantageous in sports involving side-on stances (such as golf or baseball).
To determine your ocular dominance, try the Porta test. Point an index finger at a distant object with both eyes open, then alternately close each eye to view the object with one eye at a time. The eye that views your finger as pointing directly at the object is your dominant eye.
Have a question? Send it to editors@sciammind.com
—Amelia Thomas, Rochester, N.Y.
Cognitive scientist Gregory Hickok of the University of California, Irvine, and linguist Carol Padden of the University of California, San Diego, respond:
ABSOLUTELY. 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.
But why do we talk to ourselves in any language? And why do we get the feeling that we can “hear” our own inner speech (or “see” inner signs)? One possibility is that inner speech is the voluntary use of a mechanism designed to monitor our own language output for error-correction purposes. The brain formulates a motor plan for an overt utterance, but before articulation it feeds that plan back into its language perception system, which can detect potential errors and send a correction signal if necessary. Because we have this kind of internal sensorimotor feedback loop, what is to stop us from using it to mentally rehearse a speech or to rehash a conversation? And because this internal loop has links back to our perceptual system, we have the sense that we are hearing (or for signs, seeing) our inner dialogue.
Do we have a dominant eye?
—Alexandros Syriopoulos, Athens, Greece
Mark A. W. Andrews, professor of physiology and director of the Independent Study Pathway at the Lake Erie College of Osteopathic Medicine, replies:
JUST AS MOST people have a dominant hand, almost everyone has a dominant eye, defined as the primary eye used when viewing an object at a distance. Approximately two thirds of the population is “right-eyed,” with most others being “left-eyed” and 2 to 4 percent having no discernible dominant eye. Most left-handed people are also left-eyed (and likewise for right-handers), but some individuals are cross-dominant.
Although scientists do not yet understand why we have a dominant eye, they have uncovered some interesting properties related to this phenomenon. Evidence suggests that one eye is better at sighting targets, and input from this eye may appear larger and clearer than that received from the other eye. The dominant eye also provides visual input to control movement and posture through subconscious pathways, and it has even been shown to inhibit input to the central nervous system from the opposite eye.
Knowledge and use of one’s dominant eye may be helpful in activities that require precise sighting—hunting, billiards and golf, for example. But although the idea has been proposed for years, there is no definitive evidence showing that cross-dominance is advantageous in sports involving side-on stances (such as golf or baseball).
To determine your ocular dominance, try the Porta test. Point an index finger at a distant object with both eyes open, then alternately close each eye to view the object with one eye at a time. The eye that views your finger as pointing directly at the object is your dominant eye.
Have a question? Send it to editors@sciammind.com
