The purpose of this study is to determine the accuracy of an impairment algorithm based on eye tracking while watching a short film clip, in comparison to a clinical reference standard of impairment.

Inclusion Criteria:

1. Provide written informed consent.
2. Have the ability to provide a complete ophthalmologic, medical and neurologic history as well as report medications/drugs/alcohol consumed within the 24 hours prior to tracking.
3. Be at least 18 years old.

Exclusion Criteria:

1. Be blind (no light perception), have missing or non-functional eyes.
2. Be unable to open their eyes.
3. Have a history of unresolved strabismus, diplopia, amblyopia.
4. Have a history of unresolved cranial nerve III, IV, or VI palsy.
5. Have a history of unresolved macular edema, retinal degeneration, extensive cataract, or ocular globe disruption.
6. Have a history of extensive prior eye surgery (examples include strabismus surgery, scleral buckle repair of retinal detachment, repair of blow out fractures of the orbit and any procedures that would interfere with extraocular muscle movements; prior cataract surgery or Lasik are not exclusions) or scarring.
7. Have a prior history of unresolved ocular-motor dysfunctions.
8. Have used cannabis, alcohol etc. 24 hours before study commences.
9. Be 100% naïve to cannabis usage.
10. Be pregnant.

Healthy habitual cannabis-smoking subjects, i.e., smoke or consume cannabis at least three times a week, and healthy occasional cannabis-smoking subjects, i.e., smoke or consume once a week will be recruited from the local area.