Abstract: Because deaf people differs from hearing people in so many ways, such as using a different language and having a relatively isolated way of living, a reasonable hypothesis is that their representation of world knowledge might have some unique characteristics compared to hearing people. In the current study we sought to investigate their representation of taxonomic categories. Our hypothesis was that deaf adolescents had stronger tendency of imagery representation of exemplars and weaker awareness of taxonomic categories than their intelligently-matched hearing counterparts.
In experiment 1, 15 deaf adolescents and 15 intelligently-matched hearing counterparts (31 months younger) were recruited to complete a semantic categorization task. There were two groups of experimental stimuli. One was high-typicality group composed of 16 taxonomic categories, in which 3 exemplars of higher typicality and 1 of lower typicality were selected as prime and target. The other was low-typicality group again of 16 taxonomic categories, in which 3 exemplars of lower typicality and 1 of higher typicality were selected as prime and target. All the exemplars from 25 taxonomic categories were presented in forms of words and pictures and subjects’ reaction time and accuracy were recorded. In experiment 2, 16 deaf adolescents and 16 intelligently-matched hearing counterparts (38 months younger) were recruited to complete a false memory task. There were two kinds of experimental stimuli. The first group was composed of exemplars from 13 categories, in which 3 exemplars of high typicality and 1 of low typicality were used as study item and lure. The second group was composed of exemplars from another 13 categories, in which 3 exemplars of low typicality and 1 of high typicality used as study item and lure. All the exemplars were presented in forms of words and pictures and the purpose was to further test our hypothesis.
The results showed for experiment 1, both deaf and hearing adolescents responded faster to the stimuli sets in which the primes were exemplars of higher typicality than lower typicality. But deaf adolescents responded slower to picture stimuli than words while hearing adolescents’ reaction time remained the same. Besides, deaf subjects made more errors when the primes were exemplars of higher typicality. Similar results were obtained from Experiment 2. Deaf adolescents had lower recognition accuracy when target items were of lower typicality while hearing subjects’ recognition accuracy was not influenced by exemplar typicality. For the recognition accuracy of lures, deaf subjects made more error than hearing subjects. Furthermore the hearing subjects’ recognition was influenced by exemplars typicality and item presentation mode while the deaf subjects were not.
To sum up, the current study demonstrated that deaf and hearing adolescents had similar typicality awareness. But due to their persistent dependence on the use of sign language, deaf adolescents had weaker awareness of a taxonomic category than their hearing counterparts. Instead, they had a stronger tendency to use imagery representation of taxonomic categories than their hearing counterparts

Key words: deaf adolescents, taxonomic concept, taxonomic relation