Sign iconicity and receptive vocabulary testing

Development of valid receptive sign vocabulary tests and the influence of sign iconicity on test performance were investigated. Forty items were taken from the Peabody Picture Vocabulary Test-Revised (Lloyd M. Dunn & Leota M. Dunn, 1982). For each target item, three alternative distractor items were developed to draw nonsigning participants away from a perceptual matching strategy. The sample comprised 34 deaf signing undergraduates and 36 hearing nonsigning undergraduates. Deaf students outperformed hearing students on both sets of items. Hearing students' scores on the original items were significantly higher than on the manipulated items, but both exceeded chance level (25%), indicating that many of the items were iconic for this sample. Complete elimination of iconicity is difficult for sophisticated participants. Recommendations for development of tests for signing deaf students include involvement of nonsigning hearing participants to reduce the effects of iconicity in obtaining valid results.