Date of Award


Document Type


Degree Name

Master of Arts (MA)




Word recognition studies have often focused on examining differences between young and old adults, albeit with mixed results and conclusions. Some studies have found declines or changes with age while others fail to find differences in the magnitude of robust effects including word frequency and number of meanings. One possible explanation for these incongruencies is that older adults often have higher vocabulary levels than do the young adult groups and this confounding could be masking real differences in word recognition with age. Word recognition studies have shown the Number of Meanings (NOM) Effect and Word Frequency Effect to be fairly robust in varying age groups. The present study will investigate the role vocabulary ability plays in adult-age differences and similarities in lexical processing. In the first part of the study 44 older adults (age 61-93) were compared to 44 young adults (age 18-39) on a standard lexical decision task looking at the NOM effect. In this part of the study, vocabulary ability, as measured by the WAIS-R Vocabulary subtest, was uncontrolled across the young and older adults. Results demonstrated the standard, replicable NOM effect. In the second part of the study, the same 44 older adults and a new sample of 44 young adults (age 18-44) were matched on vocabulary level. This second analysis found a stimuli by group interaction. The reaction time difference between the young and old on the ambiguous words and unambiguous words were proportionally the same, while the difference between the reaction times on the pseudowords was proportionally greater. This may lead us to fund that when we compare two groups with equal vocabulary ability, instead of two groups where the older adults have higher vocabulary ability, that some age declines in the lexical task appear which were previously hidden.