title: The role of head position and prior contraction in manual aiming.
abstract: We sought to determine if the asymmetrical tonic neck reflex influences the accuracy of self-selected arm positioning without vision and to ascertain if such accuracy is influenced by a pre-contraction of the prime movers. Participants reproduced an arm position using their abductors with the head in midline, rotated towards and away from the arm. Arm movements were made with and without a pre-contraction of the abductors. Twenty participants performed eight trials in each of the six different conditions. Compared to the midline position, participants undershot the reference position with the head turned away and overshot the position with the head rotated towards the arm. A pre-contraction caused undershooting regardless of head position. Results suggest that head position and pre-contraction may have significant and independent effects on arm positioning.
authors.affiliation: Husson University, Department of Physical Therapy, Bangor, ME 04401, United States. Electronic address: sidawayb@husson.edu.
authors.forename: Ben
authors.initials: B
authors.lastname: Sidaway
authors.affiliation: Husson University, Department of Physical Therapy, Bangor, ME 04401, United States.
authors.forename: Derek
authors.initials: D
authors.lastname: Bonenfant
authors.affiliation: Husson University, Department of Physical Therapy, Bangor, ME 04401, United States.
authors.forename: Jesse
authors.initials: J
authors.lastname: Jandreau
authors.affiliation: Husson University, Department of Physical Therapy, Bangor, ME 04401, United States.
authors.forename: Andrew
authors.initials: A
authors.lastname: Longley
authors.affiliation: Husson University, Department of Physical Therapy, Bangor, ME 04401, United States.
authors.forename: Kayla
authors.initials: K
authors.lastname: Osborne
authors.affiliation: San Francisco State University, Department of Kinesiology, 1600 Holloway Ave.-Gym 101, San Francisco, CA 94132-4161, United States.
authors.forename: David
authors.initials: D
authors.lastname: Anderson
mesh_terms: D000328:Adult; D005260:Female; D006257:Head; D006801:Humans; D008297:Male; D011187:Posture; D011597:Psychomotor Performance; D014785:Vision, Ocular
keywords: Asymmetrical tonic neck reflex; Kohnstamm phenomenon; Positioning; Response bias