%0 Journal Article %A Azevedo, Nancy %A Kehayia, Eva %A Atchley, Ruth Ann %A Nair, Vasavan N.P. %T Lexicality judgements in healthy aging and in individuals with Alzheimer's disease: Effect of neighbourhood density %D 2015 %J The Mental Lexicon %V 10 %N 2 %P 286-311 %@ 1871-1340 %R https://doi.org/10.1075/ml.10.2.06aze %K lexical processing %K lexicality judgement %K healthy aging %K neighbourhood density (N) %K lexicality %K Alzheimer’s disease (AD) %K orthographic neighbourhood %K lexical decision %I John Benjamins %X Neighbourhood density (N) has been shown to influence how lexical stimuli are accessed. In young adults, a large N is facilitatory for words but inhibitory for pseudowords in English. While there is a paucity of studies probing N as people age, results to date point towards changes in lexical processing that occur with aging. We are not aware of any studies that have sought to investigate N in Alzheimer’s disease (AD) in English. Results from the lexical decision task reported here support previous N findings for young adults. However, older adults and those with AD showed a different pattern of performance. Both were slower to respond to and made more errors to high versus low N pseudowords but, unlike young adults, older adult groups showed a decrease in sensitivity to N for words. Results suggest that the aging process may change how N is processed; older individuals are no longer as sensitive to N and this appears to be further altered by AD. In the context of the multiple read-out model of lexical processing, this change may be due to a longer time required to activate lexical neighbours which, in turn, results in differential N effects for words and pseudowords. %U https://www.jbe-platform.com/content/journals/10.1075/ml.10.2.06aze