Study aim: The aim of this study is to compare the effectiveness of Unified Transdiagnostic Intervention and Acceptance and Commitment Therapy on sensory processing sensitivity, interpretive bias, and experiential avoidance in individuals with functional seizures. Design: This study is a randomized quasi experimental trial with parallel groups and a control group involving 45 participants. Participants will be allocated to three groups using block randomization with a 1:1:1 allocation ratio. Outcome assessors will remain blinded to group allocation. The study phase is not applicable. Settings and conduct: The study will be conducted at Razi Psychiatric and Neuropsychological Center in Tabriz, Iran. After screening and obtaining informed consent, participants will be randomly assigned to study groups. Assessments will be conducted at pretest, posttest, and three month follow up by outcome assessors blinded to group allocation. Participants/Inclusion and exclusion criteria: Individuals with functional seizures aged 18 to 55 years, diagnosed by a psychiatrist or neurologist, with stable medication during the previous three months, ability to read and write Persian, and informed consent will be included. Individuals with severe psychotic disorders, severe neurological comorbidities, inability to participate regularly in treatment sessions, or changes in psychiatric medications during the study will be excluded. Intervention groups: The first group will receive Unified Transdiagnostic Intervention in 12 weekly group sessions. The second group will receive Acceptance and Commitment Therapy in 8 weekly group sessions. The control group will remain on a waitlist and will not receive structured psychological intervention during the study period. Main outcome variables: Sensory processing sensitivity; interpretive bias; experiential avoidance