1. 9 Eye behavior
2. American Council on the Teaching of Foreign Languages. (2012). ACTFL proficiency guidelines. ACTFL. https://www.actfl.org/sites/default/files/guidelines/ACTFLProficiencyGuidelines2012.pdf
3. American Educational Research Association, American Psychological Association, & National Council on Measurement in Education. (2014). Standards for educational and psychological testing. American Educational Research Association.
4. Mixed-effects modeling with crossed random effects for subjects and items
5. OpenFace 2.0: Facial Behavior Analysis Toolkit