Twitch force. Box and whisker plot showing that (A) radiation treatment was associated with significantly (p = .01) reduced medial nerve twitch tongue force in both age groups, and (B) that age had a significant (p = .04) effect on medial nerve twitch force. Boxes depict the interquartile range (IQR), with a line at the median. Whiskers extend to the last observation within 1.5x the IQR. The closed circles are observations beyond 1.5x the IQR. Y = Young Adult Control; YR = Young Adult Radiated; O = Old Control, OR = Old Radiated.