The alpha value obtained 0. Furthermore, inter-rater and intra-rater reliability was also high. These results are consistent with those of the study conducted by Crawford and Warrington Furthermore, content and construct validity of the Persian HMGT were determined in this study, and it can be concluded that it is a highly valid test like its English version These findings are consistent with the previous study conducted by the test developer 9.
Discussion The first aim of this study was to adapt English HMGT to Persian version and to establish the reliability and validity of this instrument. Then the nature of the test and its required strategies were investigated. Generally, there was a positive correlation between HMGT and semantic and phonemic fluency tests in a group of Persian-speakers. As a result, some similarities between underlying processes in these three tests are predictable.
HMGT was originally designed by Warrington to evaluate executive function as a measure of frontal lobe dysfunction 9. It is hypothesized that HMGT requires two processes: Directed search and flexibility, and manipulation of various conceptual representations 9 - In fact, finding different meanings of a homophone requires searching within and between existing conceptual categories Based on previous studies, semantic fluency is highly dependent on lexical knowledge, and phonemic fluency is deeply affected by mental flexibility These findings can unfold this significant correlation between HMGT and fluency tests since HMGT requires both lexical knowledge like semantic fluency and mental flexibility like phonemic fluency.
Moreover, all these three tests are sensitive to frontal lobe dysfunction, making this correlation even more sensible and predictable 9 , Qualitative analysis of fluency tests further clarifies the underlying word finding processes in fluency tests.
Troyer posits that clustering reflects the semantic organization in the brain, and switching is an executive function, including strategic search, shifting, and mental flexibility 3 , Our findings revealed that clustering and switching scores in both fluency tasks correlate positively with HMGT scores. However, HMGT score is more highly related to the number of switches than to the mean cluster size across the two fluency tasks. She and her colleagues found the same pattern except in correlation between HMGT and phonemic mean cluster size which was not correlated with the HMGT at all.
Switching between semantic and phonemic subcategories requires strategic search, shifting, and mental flexibility. Thus, the correlation between switching and homophone meaning generation is reasonable since both of them are considered an executive function 3 , 9 , 19 , However, the correlation between the HMGT and the semantic and phonemic cluster size was smaller than the correlations with the number of switches especially for phonemic clusters.
Phonemic clusters are made based on similarities of sounds, while semantic clusters manifest organization of knowledge into conceptual categories. This semantic organization is also required in homophone meaning generation, but the similarities of sounds cannot help meaning generation 3 , 9 , 19 , Consequently, HMGT was more correlated with semantic clustering than phonemic clustering. This does not apply to English homophones since many of them may have semantically related meanings.
As a case in point, one word can be both a noun and a verb. As a result, it seems that semantic processes required in semantic clustering are not completely the same as the activation of semantic representations in HMGT in the Persian language. This study suffers from all of the limitations inherent in any nonrandomized sampling.
In this context, the sample size of the data set available was not large enough to permit the normalization process. These troublesome methodological issues remain to be dealt with in future researches.
Conclusion In conclusion, this study proposes that Persian HMGT is a valid and reliable instrument which shares many underlying mental processes with verbal fluency tests. HMGT is an easy test to score, user-friendly and efficient in assessing word finding performance, especially lexical search and manipulation of various conceptual representations with no time constraints.
Based on these evidences, we suggest that the Persian HMGT be used for language evaluation in clinical settings and research studies. We would like to acknowledge Mr. Payam Mihanparast for his help with data collection and compilation. We also would like to thank volunteers for their involvement in this study. Notes Cite this article as: Developing the Persian version of the homophone meaning generation test. Searching for the right word: Performance on four word retrieval tasks across childhood.
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