Date of Award


Degree Type


Degree Name

Doctor of Philosophy


A series of four experiments are presented which contrast the hypothesis that synonymy is semantically represented with the hypothesis that synonymy is lexically represented. They also stress the importance of task focal information in the interpretation of experimental results. Current mental models appear to operate with the implicit assumption that synonymy is represented semantically. The findings of Biggs and Marmurek (1983, 1990), that synonymous word-picture prime-target presentations produced greater naming facilitation than their repeated counterparts, run counter to the semantic representation hypothesis. The current investigations manipulated the type and degree of processing overlap between prime and target items by using specific tasks for primes and targets. In Experiment 1 primes were named and targets were categorized. This removed lexical overlap, present in Biggs and Marmurek, and made task focal information different for primes and targets. The results showed greater facilitation in the repeated word-picture condition than in the corresponding synonymous condition. In Experiment 2 primes were categorized and targets were named. This manipulation re-instated lexical processing overlap in the word-picture conditions, while maintaining differences in focal information. The results showed statistically significant and equivalent facilitation for word-picture presentations in repeated and synonymous conditions. In Experiment 3 primes and targets were independently categorized. This manipulation removed lexical processing overlap, and made prime and target focal information similar. The results for repeated and synonymous word-picture presentations replicated those in Experiment 2. Experiment 4 required subjects to respond "yes"/"no" about category inclusiveness to pairs of sequentially presented items. The results indicated that response latencies for synonymous word-picture pairs were significantly faster than for those pairs in the repeated condition and that those conditions were faster than the related condition. Errors in the repeated and synonymous conditions were approximately equal and much lower than in the related condition. Combined error and response latency patterns suggested focal information was lexically based. These results favour the lexical hypothesis of synonym representation. Further discussion focuses on the implications of focal information monitoring for the interpretation of experimental outcomes.



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