The researchers designed a software based on a head-mounted displays for virtual reality (HMD-VR) to evaluate the reaction time to stimuli presented at right or left visual field. The study will recruit 100 stroke patients with hemisphere lesions (50 patients for right and left each) and 100 age-matched healthy controls. The participants will conduct a simple reaction time task in VR, with stimuli designated in the left or right hemi-field. The stroke patients will also received traditional tests for hemi-neglect. Test-retest reliability of the assessment will be conducted in a subset of the control group. The stroke patients will be followed in 3-4 weeks.

The researchers designed a software based on a head-mounted displays for virtual reality (HMD-VR) to evaluate the reaction time to stimuli presented at right or left visual field. The study will recruit 100 stroke patients with hemisphere lesions (50 patients for right and left hemisphere each) and 100 age-matched healthy controls. The participants will conduct a simple reaction time task in VR, with stimuli designated in the left or right hemi-field. The stroke patients will also receive traditional tests for hemi-neglect. The researchers will also collect the demographic data, cognition function and daily activity function. Test-retest reliability of the assessment will be conducted in a subset of the control group. The stroke patients will be followed in 3-4 weeks. The researchers will compare the results of a traditional hemi-neglect tests and VR-based tests and their changes in two occasions.

Inclusion Criteria for stroke patients:

1. aged at least 20 years old
2. diagnosed with stroke involving unilateral MCA and ACA territory
3. with unilateral upper limb with normal function
4. neurologically and medically stable.

Inclusion criteria for control group:

1) healthy adults, age-matched to stroke patients

Exclusion Criteria for both groups:

1. with history of neurological or psychiatric conditions other than stroke;
2. significant cognitive or speech problems that cause difficulties to cooperate with testing;
3. significant visual problems (such as color blindness, visual loss, cataract, glaucoma or other major eye condition)
4. upper limb musculoskeletal disorders to cause difficulties to use the keyboard or controller;
5. history of seizure, vestibular dysfunction or vertigo
6. can't tolerate HMD-VR

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