A 66-year-old man comes to clinic because of a 1-year history of tremor that began in his right hand. His wife reports that the tremor is most noticeable when he is sitting quietly watching television and that it improves when he reaches for objects or uses utensils. He also notes smaller handwriting over the past several months. He drinks 2 cups of coffee daily and rarely drinks alcohol. Family history is negative for tremor. Neurologic exam shows a 4–6 Hz "pill-rolling" tremor of the right hand that decreases with voluntary movement. Which of the following best describes the characteristic setting in which this patient’s tremor is most prominent, and which alternative condition classically has tremor that is most prominent in the opposite setting?