Overview
How participants perceive the position of their own hand in various contexts will be examined. This will include changing the visual display to suggest the hand is in a slightly different position, and asking participants to indicate where they think it is by pointing with their other hand.
Description
Hand position can be estimated visually, from an image on the retina, and proprioceptively, from sensors in the joints, muscles, and skin. The brain is thought to weight and combine available sensory estimates to form an integrated multisensory estimate. Inherent in this process is the capacity to realign one or both sensory estimates when they become spatially mismatched, as when washing dishes with the hands immersed in water, which refracts light. It is generally assumed that if a person knows about the sensory mismatch somehow, the realignment will not occur. This assumption will be tested in two experiments by giving people this information in different ways. Expt. A: Conscious awareness of the mismatch will be presented in different ways, or absent. Expt. B: Movement error feedback will be presented in different ways, or absent.
Eligibility
Inclusion Criteria:
- Between the ages of 18-45 years old
- Right-handed.
- Covid has been found to have neurological effects in some people, but mostly the effects on sensorimotor control and neurophysiology are unknown. So we will only include individuals who report being free of Covid symptoms in week preceding testing.
Exclusion Criteria:
- Past or present history of seizure, stroke, any brain or peripheral nerve disease, severe head trauma, or spinal cord surgery.
- Learning or attention conditions such as ADHD.
- Orthopedic or pain conditions, or a history of seriously injured bones, joints or muscles in either arm.
- Lack of normal or corrected-to-normal vision.