The effects of presentation modality upon learning in a comprehension task using oral, manual, and dual mode stimulus...

Interest in how and why the use of nonspeech symbols such as manual signs facilitates the communication development of language-handicapped individuals has been growing. One question of interest is whether comprehension is facilitated because manual sign cues are in the same stimulus modality (visual) as the objects or events to which they refer, in contrast to oral cues, which are in a different modality (auditory). Another question is, when total communication (words and manual signs) is used, which modality, visual or auditory, actually controls responding? Previous analogue research with normal adults has not controlled for representational iconicity and/or has utilized tasks different than those used with handicapped populations. In this study, 15 undergraduate students were trained to a criterion to identify abstract forms in response to manual sign, CVC nonsense syllables, or combined manual sign plus CVC nonsense syllables. Signed English signs normally representing common objects were matched to the abstract forms. Results from learning probes indicated that performance improved significantly following training for all types of labels. Performance on learning probes of responses to manual labels was significantly poorer than performance on probes of responses to oral labels, to manual labels previously used in combined labels, and to oral labels previously used in combined labels. However, there was no difference in performance among these latter three conditions. These results suggest that the facilitative effects of manual sign labels upon comprehension found in other research may be due to the iconic relationship between signs and their referents.