![Sample our Behavioral Sciences journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/110801/TOC-Subject-Sample-2021-Behavioral-Sciences.jpg"})
Abstract
Background: A common complaint among the healthy ageing population is the increased frequency of word‐finding problems. The Transmission Deficit Hypothesis (TDH; Burke, MacKay, Worthley, & Wade, Citation1991) proposes that word retrieval difficulties in healthy ageing are due to a selective failure in the transmission of available semantic/syntactic information to the phonological system, as opposed to generalised slowing. This study examined the relative timing of sensory processing and substages in phonological retrieval, in healthy young and old adults, using event‐related potential (ERP) measures.
Aims: To examine the effects of age on retrieval of segmental and syllabic information within phonological processing, and to consider whether age‐related changes in phonological processing are a result of relatively early (sensory: visual) delays or to true stage‐specific phonological processing delays.
Methods & Procedures: A total of 16 healthy young and 16 healthy old adults performed an implicit picture‐naming task while making a segmental or syllabic decision in a Go/No‐go paradigm. The ERP component N2d (No‐go minus Go waves), reflecting response inhibition to the phonological decision, and the visual evoked potential (VEP) components, reflecting visual processing of the stimuli, served as dependent measures.
Outcomes & Results: Both reaction time (RT) and N2d data demonstrated later latencies in the old than young group on both the segment and syllable tasks. More specifically, the N2d effect was found between 301 and 450 ms on the segment task and between 351 and 450 ms on the syllable task for the young adults. The old group demonstrated the N2d effect later, between 351 and 500 ms on the segment task, and 451 and 500 ms on the syllable task. By contrast, no substantial differences in the latencies of the VEPs were observed between groups for either task.
Conclusions: The behavioural and N2d findings provide support for the TDH that there are age delays at the phonological level of encoding. The VEP findings confirm that stage‐specific phonological processing deficits were not a consequence of a more general ageing effect. The cause of this delay in accessing phonological information is unknown, but it will be important to explore whether healthy old adults might benefit from phonological practice to improve retrieval. It will also be important to determine the extent to which these age‐related findings enter into clinical naming disorders, such as anomia, and the extent to which individuals with anomia may be affected at different substages of retrieval.
Keywords: