Bilateral Facial Communication Requires Duration: How Mirror Reversal Truncates Expression before Messaging Completes

Non-reversed ("True") mirrors produce dramatically different facial expression patterns than conventional reversed mirrors. FACS analysis (N=22) reveals large effect sizes (Cohen's d=1.0-1.6) for sustained genuine expression markers (AU6/AU12), with True Mirror enabling 5-30x longer expression duration. Communication requires duration; reversal truncates messaging.