A thesis submitted in partial fulfilment of - Queen Margaret University

5.18 FACTORS AFFECTING THE LEARNING OF NEW VOCABULARY
As discussed above, various factors were considered likely to have affected the
learning of new vocabulary by the participants with aphasia. An exploratory
statistical method was chosen to identify groups of participants who exhibited
similar characteristics related to these potentially influencing factors. The
immediate recall scores of participants were initially chosen for this analysis as
these scores reflected the learning performance of each individual (whereas the
delayed recall scores reflected the retention of newly learned vocabulary). As
individual cluster groups were not pre-determined and the data sample was less
than 200 a hierarchical cluster analysis was applied to the group results for total
immediate recall raw scores (see Table 5.1). Following this, hierarchical cluster
analyses were conducted for all variable factors (personal attributes, cognitive
abilities, severity of aphasia and non-linguistic learning). This data was
evaluated to ascertain how variables clustered participants into particular
groups. The findings are discussed in relation to the learning of new vocabulary
by the aphasic participants.
Following these analyses, hypotheses were formed in consideration of the
literature and the various performances of participants. These hypotheses were
then tested with the aim of forming predictions regarding the ability of individuals
in the wider population of people with aphasia to learn new vocabulary. Each
hypothesis was tested using quantitative correlation statistics as well as
qualitative observations. The normality of the data was assessed and twelve of
the data sets were found to have normal distributions. Two factors (non-linguistic
learning and executive function) were skewed and were not normally distributed.
However, as most parametric tests are reasonably robust, they can tolerate a
certain amount of deviation from parametric assumptions. Therefore, it was
considered that parametric assumptions were largely satisfied and a Pearson
correlation coefficient was chosen to test the hypotheses (see section 5.18.2).
These hypotheses were evaluated by correlating the data from Table 5.1 with
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