Perceptual Anchors and the Dispersion of Nasality Ratings

This investigation studied the effects of perceptual anchors on the dispersion and reliability of listener ratings of nasality.

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.

Of the speakers, 95 were children followed by a craniofacial team and five were children without histories of speech disorders.

The outcome measures were 12,900 ratings of nasality on a seven-point scale.

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).

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.