A system of hardware and software that captures and processes in real time biometric data of patient responses and reactions to tablet-based valenced pictorial stimuli to facilitate diagnosis of mental health conditions of the patient including Autism Spectrum Disorder (ASD), Attention-Deficit Hyperactivity Disorder (ADHD), Traumatic Brain Injury (TBI), and Post-Traumatic Stress Disorder (PTSD) is provided. Via transparent, non-invasive biometrics induced by pictorial stimuli, the system removes potentially threatening testing instrument characteristics that can invalidate authentic assessment. The system will mitigate or remove other threats to assessment validity including subjective judgments as well as bias on the part of the examiners who are completing subjective surveys. The biometric assessment is incorporated within a variety of engaging game formats that appeal to males and females of nearly any age that speak a variety of languages and encompass a wide spectrum of demographics and ethnicities.