For at-risk participants:  Inclusion criteria:  A score of or above 9 in the Chinese version of the 16-item Prodromal Questionnaire (CPQ-16), or a score of or above 8.18 in the Chinese version of Community Assessment of Psychic Experiences with 15 items (CAPE-C15), or a score of or above 17 in Schizotypal Personality Questionnaire-Brief (SPQ-B); the age between 15-24 years; score > 60 in The Chinese version of Edinburgh Handedness Inventory (CH-EBI) to ensure right handedness; and score ≥ 22 in Montreal Cognitive Assessment Hong Kong Version (HK-MoCA) to ensure no serious cognitive deficits so that they can understand instructions.  Exclusion criteria:  psychiatric diagnosis by self-report; cardiovascular, neurological, muscular or orthopedic diseases that may affect hand movements; taking psychiatric medications; substance abuse; and being pregnant.  For schizophrenia participants:  Inclusion criteria:  a diagnosis of schizophrenia without other psychiatric diseases; the age ≥ 18 years; score > 60 in CH-EBI to ensure right handedness; and score ≥ 22 in HK-MoCA to ensure no serious cognitive deficits so that they can understand instructions.  Exclusion criteria:  cardiovascular, neurological, muscular or orthopedic diseases that may affect hand movements; substance abuse; and being pregnant.