Perceptual Anchors and the Dispersion of Nasality Ratings

Abstract

Objective This investigation studied the effects of perceptual anchors on the dispersion and reliability of listener ratings of nasality. Design Listeners (N = 129) were assigned to one of six listening groups. Each group rated nasality independently for 100 speech samples on a seven-point scale that ranged from 1 = normal nasality to 7 = severe hypernasality. The anchors used were examples of a 1, 3, 4, 5, and/or 7 on the rating scale. These anchors were played selectively to group 2 (4), group 3 (1 and 7), group 4 (3 and 5), group 5 (1, 4, 7), and group 6 (7). Group 1 had no anchor. Participants Of the speakers, 95 were children followed by a craniofacial team and five were children without histories of speech disorders. Main Outcome Measures The outcome measures were 12,900 ratings of nasality on a seven-point scale. Results Q values showed that group 5, which was the only group to receive three anchors, had the lowest, or best, Q value (0.78), and group 1 (no anchor) had the highest, or worst, Q value (0.99). Across groups, the most reliable ratings were those at scale values 1 (Q = 0.46) and 7 (Q = 0.56). The least reliable ratings were at scale values 3 (Q = 1.01), 4 (Q = 1.03), and 5 (Q = 1.06). Conclusions Nasality rating reliability/dispersion was influenced by the presence and location of anchor stimuli. Consistent with absolute judgment theory, nasality ratings showed a strong end effect.