Brain Mechanisms of Attention and Pain in Youth With FAPD

Inclusion Criteria: 1. Children (boys and girls) between 11-16 years of age and their parent/primary caregiver. 2. Meets criteria for one of two study groups: * FAPD: based on physician diagnosis of FAPD confirmed by a validated Rome IV measure. * HC: based on a rule out of an FAPD diagnosis (using the Rome IV measure). We will recruit approximately 50% of HCs with and without clinical levels of anxiety (e.g,. SCARED cut-off score greater than or equal to 25) to match the anxiety levels anticipated in the FAPD group. 3. Sufficient English language ability necessary to complete study measures and protocol Exclusion Criteria 1. Children with significant medical condition(s) with an identifiable organic cause including those that may account for abdominal pain symptoms (e.g., Inflammatory Bowel Diseases such as Ulcerative Colitis and Crohn's Disease). Rationale: Children with a significant medical condition may impact the study results. Further, youth with organic conditions that include abdominal pain may not meet criteria for FAPD even if they present with similar symptoms. 2. Children with a documented developmental delay, autism spectrum disorder, a previously diagnosed thought disorder (i.e., psychosis), or bipolar disorder will be excluded. Rationale: These comorbidities may confound the study aims by impacting the dependent measures. 3. Significant visual, hearing, or speech impairment. Rationale: Children will be excluded if they are not able to see the testing stimuli, hear the test examiner, or respond verbally to the test examiner, even with the help of corrective or assistive devices (e.g., glasses, hearing aids). 4. Organic brain injury. Rationale: Children must not have a history of epilepsy, a head trauma associated with a loss of consciousness, or any other organic disorder since these conditions could possibly affect brain function and cognition and interfere with study results. 5. \*Other exclusionary criteria specific to the fMRI component of the study: * Participants with an implant such as a cochlear implant device, a pacemaker or neurostimulator containing electrical circuitry or generating magnetic signals will be excluded. Participants must also not have any significant ferrous material in their body that could pose the potential for harm in the fMRI environment or cause signal suppression of key regions (i.e. orthodontia). Rationale: Implant devices can malfunction and/or be damaged. Strong magnetic fields in the fMRI environment can cause some metallic objects to move and/or heat, and therefore pose a safety risk. All children will be screened prior to participation using a standardized questionnaire in the fMRI component of the study to ensure that the fMRI magnetic fields will not pose any risk to their safety. * Female participants who report current/suspected pregnancy will be excluded. Rationale: There is minimal yet potential fetal risk due to electromagnetic radiation from the MRI. Female participants who self-report that they may be pregnant will be excluded from the study. * Participants with evidence of claustrophobia will be excluded. Rationale: Such participants may experience extreme distress when entering the fMRI scanner. Claustrophobia will be assessed using a validated module of the Anxiety Disorders Interview Schedule as part of the initial screening process. Youth will be excluded from participating if they report excessive fear of enclosures. * Note that these exclusionary criteria do not apply to those recruited for the study's pilot portion.