A 35-year-old woman presents with a 2-year history of recurrent abdominal pain that multiple gastroenterologists have been unable to explain after extensive workup. She brings detailed medical records from 6 different hospitals and becomes tearful when describing her suffering. The PMHNP notes that the patient spends several hours daily researching her symptoms online and has significantly reduced her work hours due to health anxiety. During the interview, the patient is observed surreptitiously placing a thermometer near a hot cup of coffee before reporting a fever to the nursing staff. Which assessment finding most clearly differentiates factitious disorder from somatic symptom disorder in this presentation?