Spoken word production and its breakdown in aphasia.
This thesis examines the processes involved in spoken word production.
The disorders of naming observed in fifteen aphasic subjects are
analysed in detail and the results related to current models of spoken
word production. The data is used to support and refute predictions
made by these models and the model is presented which best fits the
Each of the fifteen aphasic subjects was tested using a range of tasks
for assessment of both comprehension and production deficits. Their
performance on a picture naming task was examined in detail.
Statistical analyses were performed to study the effects of a number
of variables on naming performance for the group as a whole and for
individual subjects. These variables included written word frequency,
familiarity, imageability, concreteness, word length (in terms of
number of syllables and number of phonemes) and articulatory/
Although there was no significant relationship between overall naming
performance and comprehension, the production of semantic errors was
significantly correlated with semantic errors in the comprehension of
high imageability items. There was also found to be no relationship
between the production and detection of phonological errors and input
In contrast to many previous studies, there was not found to be a
significant effect of written word frequency on picture naming for
this group of aphasic subjects. However, a significant effect of
familiarity was found and it is argued that this serves as a more
accurate measure of spoken word frequency than the measures of written
word frequency commonly used. Similarly, imageability was found to be
a better measure of the influence of a semantic deficit on naming than
concreteness. The majority of patients showed a significant effect of
word length on the production of phonological errors and this length
effect was predominantly found to be due to the number of phonemes,
rather than the number of syllables, present in the word. The
theoretical implications of these results are discussed.