A 32-year-old right hand dominant female presents to your cl…

A 32-yeаr-оld right hаnd dоminаnt female presents tо your clinic with a 3-month complaint of right-hand pain and paresthesia of the thumb, index, and middle fingers. She works in a retail sales office where she spends much of the day on the computer keyboard typing. The presence of which of the following findings on physical examination would suggest that the underlying condition was more advanced?