Both Casper and PREview are situational-judgment tests that some medical schools require alongside your application. Instead of testing knowledge, they assess how you reason through everyday ethical and interpersonal situations. Casper, from Acuity Insights, is timed and mixes typed and video responses. PREview is the AAMC's own version.
You cannot cram facts for either one, but a little preparation genuinely helps. Take the free official practice test so the format is not a surprise, learn a simple framework for thinking through ethical scenarios, and practice reasoning out loud so you can organize a calm, thoughtful answer under time pressure.