Inclusion Criteria:  Children between 16 and 30 months of age. No acute illnesses by physical observation. Normal or corrected-to-normal vision, and normal or corrected-to-normal hearing. Communicate meaningfully with patent in English, and the principal investigator /the study team. Parent or legal guardian is able to read and understand the Informed Consent Form. Parent voluntarily provides written informed consent.  Exclusion Criteria:  Genetic disorders (e.g., Fragile X, Williams Syndrome, Tuberous Sclerosis, muscular Dystrophy, Neurofibromatosis, Down Syndrome). History or presence of a clinically significant medical disease or a mental state that might confound the study result as assessed by the investigator, such as severe hearing or visual impairment; or uncontrolled epilepsy or seizure disorder, et al. Acute exacerbations of chronic illnesses likely to prevent successful data collection. Receiving therapies that may affect vision. Therapies that may affect the ability to focus. Known allergies or sensitivity to the plastic, leather, or metal components. Unable or unwilling to sit in a child safety seat. Use of any investigational drug, therapies or diagnostic device within the past 14 days.