Non-invasive Brain Stimulation in Adults Who Stutter

Inclusion Criteria: * history of persistent developmental stuttering * stuttering severity ranging from mild to very severe, specifically Stuttering Severity Instrument (SSI) total score of 20 (mild) or higher and stuttering rates of 3% or higher * scores within 1 standard deviation of the norm on the standardized tests for the study Exclusion Criteria: * received any treatment for stuttering within the past year * other neurological conditions such as Tourette's syndrome or post-traumatic stress disorder * taking any medications/drugs that affect brain function * history of past or current mental illness for example, schizophrenia that may affect brain development and function * history of serious medical or neurological illness such as epilepsy and Parkinson's disease * history of closed head injury (e.g., concussion) * history of reading disorders * hearing loss * taking any medication, prescription or non-prescription with any psychotropic effects at the time of the study * metal or electronic implants such as cochlear implants, and pacemakers