This study investigated lexical extension and overextension by three blind children, ages 1;8, 2;1 and 2;5, who had vocabularies of at least 50 words but did not yet produce two-word utterances. Theories of semantic development take it for granted that vision provides the child with access to a great deal of the information necessary for the development of meaning, including much of the knowledge about size, shape, and movement of referents. Through vision, the child is able to form concepts on which word meaning is based, and extend the domain of application of words from original referents by recognizing other instances of that word. Despite this, surprisingly little research has focused on semantic development by blind children. Results of the few relevant studies indicate that blind children rarely extend or overextend their words, and attribute this inability to either (1) a lack of experience with other similar referents, or (2) an inability to form categories that underlie lexical extension and overextension. The blind children were given objects to name during a play session. These objects were (1) new examples of an item the child already named, providing opportunity for the child to extend known words to proper, novel referents, or (2) members of a different nominal category, but differing from an item the child already named in one or two criterial features, thus providing opportunity for the child to overextend. Data on spontaneous extension and overextension was also collected through analysis of utterances produced during experimental sessions and reported in parental diaries. Results indicated that all children extended and overextended their words, both spontaneously and in experiments; visual impairment did not prevent the children from recognizing other exemplars of a referent, or from applying words they knew to objects similar to original referents but, on the basis of criterial features, members of other nominal categories. Performance during two sorting tasks indicated that the children did not have impaired ability to form categories—all three children displayed classificatory behaviour during the sorting activities. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

Landau and Gleitman's experiments investigating a blind child's meaning for look, as it applied to herself, were replicated with a three year old boy who was totally blind, and had no concomitant disorders. Several commands to look were presented within informal play sessions. Responses to the look commands were compared with responses to instructions to touch, listen and taste. Experiments were video recorded for subsequent analysis. It was found that the blind child associated the haptic perceptual modality with the visual verb, in that an instruction to look at an object elicited manual exploration of the object. His meaning for look was distinct from his meanings for the other perceptual verbs. These findings were consistent with Landau and Gleitman's findings. Landau and Gleitman's interpretation, of how a blind child's mastery of visual terms bears on the word/meaning mapping problem, is critically discussed. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate