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Abstract

Background: This thesis represents the application of cognitive psychology, specifically phenomena reported in the concepts and categorisation literature, to autism research. The studies reported here tested the claim that prototype formation and therefore prototype effects are impaired in autism (Klinger & Dawson, 2001). The claim is supported by other theories: weak central coherence (Frith, 1989; Frith & Happe, 1994) and a reduced perception of similarity (Plaisted, 2001). Additionally, supporting evidence suggests that individuals with autism do not show prototype effects (Klinger & Dawson, 2001; Plaisted, O'Riordan, Aitken, & Killcross, Submitted). Method: There were three studies each with two participant groups: high-functioning children with autism and a matched control group of typically developing children. The first study used stimulus cards to test whether prototype effects were shown in recognition memory (Experiments 3.1 - 3.3). The second used dot pattern stimuli presented on computer to compare the influences of recognition and categorisation on prototype effects (Experiment 4.1). The final study used stimulus cards to investigate the influence of ambiguity on children's categorisation responses (Experiments 5.1 - 5.3). Results: The majority of participants with autism demonstrated prototype effects similar to those of controls in all three studies. Other findings reported for the autism groups were reduced visual recognition memory for old, meaningless stimuli (Experiment 4.1) and reduced category membership decisions (Experiment 5.3). Conclusion: The convergence of experimental findings showed that most children with autism do show intact prototype effects. These findings limit the theoretical claims presented earlier. The discussion (Chapter 6) also summarises suggestions for future research into visual recognition memory and category membership decisions. Finally it is argued that a major implication of the research presented in this thesis together with other relevant findings is that considerable instability exists (on whether or not participant group differences are shown) both with the demonstration of prototype effects and in the perception of similarity. It is argued that elucidating the causes of instability in the latter is a priority for future research.

Publication Type:	Thesis (Doctoral)
Subjects:	B Philosophy. Psychology. Religion > BF Psychology
Departments:	School of Health & Psychological Sciences > Psychology Doctoral Theses School of Health & Psychological Sciences > School of Health & Psychological Sciences Doctoral Theses

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