Frames of reference

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geocentric

orientation of head with respect to vertical influence of gravity

This frame of reference ensures that the head, a "sensory platform," is aligned according to its gravitational environment. This frame of reference is the only one which permits anticipatory (feedforward) head control during voluntary movement.

The system derives two other frames of reference from the geocentric one:

• egocentric

  orientation of head with respect to body

• exocentric

  orientation of head with respect to objects in environment

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Sources: Di Fabio, R.P., & Emasithi, A. (1997). Aging and mechanisms underlying head and postural control during voluntary motion. Physical Therapy, 77, 458-475.