Symptom modeling has been used to explain the development of psychogenic nonepileptic seizures (PNES) in predisposed patients, but has been understood only in the context of individuals who have both PNES and epileptic seizures. Our aim in the study described here was to learn whether this concept applies to patients with PNES who do not have epileptic seizures, that is, to determine whether the prevalence of having personally witnessed a seizure prior to the occurrence of their event differs in patients with PNES and those with epileptic seizures. We interviewed 27 patients with PNES and 35 patients with epileptic seizures. A significantly larger number of patients with PNES (66%) admitted to having witnessed a seizure prior to their event compared with patients with epileptic seizures (11%) (P<0.001). This suggests that symptom modeling plays a key role in the development of PNES, even among individuals without a coexisting history of epilepsy.