Standardization of the Lexical-Semantic Subtests of the Persian Version of the Montreal Protocol for the Evaluation of Communication (PMEC)

AbstractNumerous studies over the past half-century have demonstrated that, in addition to the dominant role of the left hemisphere in language processing, the right hemisphere also contributes to the processing of various linguistic and communicative aspects. “The Montreal protocol for the evaluation of communication (MEC)”, developed in 2004, is a comprehensive tool to evaluate four communication skills, namely prosodic, lexical-semantic, discourse, and pragmatic skills in patients with right hemisphere brain damage. This study aims to introduce and standardize four subtests of the lexical-semantic skill (verbal fluency without constraint, verbal fluency with orthographic criteria (b), verbal fluency with semantic criteria (clothes), and semantic judgment) of the Persian version of the MEC. To this purpose, 150 healthy Persian-speaking adults were assessed in two age groups (25–44 and 45–64 years) and two educational levels (less than 12 years, and 12 years or more of formal education). The results confirmed the validity and reliability of the subtests in evaluating lexical-semantic language abilities in Persian. Also, consistent with the previous research on the PMEC’s pragmatic skill, the education variable had a significant than the age variable in most subtests.IntroductionBased on numerous studies conducted in various languages, it has been widely accepted that individuals' linguistic and communicative abilities can be disrupted as a result of damage to the right hemisphere and certain non-traditional language areas. Lexical-semantic skills are among the competencies that may be affected in various ways following injury to the right hemisphere. The primary aim of developing the initial version of the “Montreal protocol for the evaluation of communication (MEC)” (Joanette et al., 2004), originally developed in French, was to evaluate different types of communicative skills in patients with right-hemisphere damage. This protocol, considered as the most comprehensive and precise tool to date for assessing the communicative abilities of the right hemisphere, has been translated into several languages over the past two decades, including Persian. The present study aims to present the results of the standardization process of the subtests related to the lexical-semantic section of the protocol in Persian.Literature ReviewPrevious studies have demonstrated the significant role of the right hemisphere in semantic and lexical processing. Conducting a lexical decision task, Day (1977) found that the right hemisphere is capable of recognizing and classifying concrete nouns; however, its ability to process abstract nouns is markedly limited, suggesting that the processing of abstract terms predominantly occurs in the left hemisphere. Joanette et al. (1988) indicated that the right hemisphere’s role is crucial in certain aspects of lexical-semantic processing essential for speech production. Goulet et al. (1997) reported that the right hemisphere plays an important role in word fluency tasks, and the right hemisphere-damaged patients do not show a dissociation in their performance with respect to the semantic-orthographic criteria of the words. Passeri et al. (2015) concluded that both hemispheres are involved in categorizing common nouns, with the right hemisphere contributing more extensively to the semantic categorization of uncommon or abstract nouns. Torabi (2020) has shown that Persian-speaking patients with right hemisphere damage exhibit more heterogeneous deficits in lexical-semantic skills compared to the control group, confirming the involvement of the right hemisphere in semantic processing. Moreover, Modarresi Tehrani et al. (2021) based on the Persian version of the Montreal protocol found that the lesions in the right hemisphere can impair lexical-semantic processing in Persian-speaking patients. Collectively, these findings suggest that the right hemisphere is essential to semantic processing, particularly for complex, abstract, or non-ordinary words, and damage to this hemisphere can result in significant deficits in lexical-semantic functions.MethodologyTo standardize the Persian version of the MEC protocol, 150 individuals participated in the study. All participants were monolingual Persian speakers, right-handed, literate, and in good health. The participants were divided into two age groups (25-44 years and 45-64 years) and two educational groups (those with less than 12 years of formal education and those with 12 years or more of formal education). Four subtests of the Persian version of the protocol, namely verbal fluency without constraint, verbal fluency with orthographic criteria (b), verbal fluency with semantic criteria (clothes), and semantic judgment were administered in a consistent order. All responses were recorded using a recording device (SONY Stereo IC Recorder ICD-UX560F, China). Scoring was performed in two stages based on the original test criteria in French. In the first stage, the examiner assigned scores to each participant’s responses. In the second stage, while listening to the audio files, the scores were checked according to the scoring manual.ResultsPsychometric analyses were conducted to evaluate the validity of the four lexical-semantic subtests of the Persian version of the protocol, focusing on two validity indices, the content validity ratio (CVR) and the content validity index (CVI). To this end, three questionnaires assessing the validity of each item based on necessity, relevance, and face were presented to several language experts. For the necessity questionnaire, the minimum acceptable values for the CVR and CVI were 0.60 and 0.80, respectively, for the relevance questionnaire 0.76 and 0.88, and for the face questionnaire 0.583 and 0.792 for each question separately. The analysis of these scores confirmed the validity of the questions within each questionnaire. Additionally, the overall CVR and CVI values across all questions in the three questionnaires were calculated. These aggregate values were 0.885 and 0.943 for the necessity questionnaire, 0.905 and 0.953 for the relevance questionnaire, and 0.854 and 0.928 for the face questionnaire, indicating a high level of validity for all three instruments. The reliability analysis was also conducted using Cronbach’s alpha coefficient for the semantic judgment subtest, which yielded a value of 0.77, confirming the internal consistency and reliability of this subtest.To examine the effects of the two variables, age and education, on the results of each subtest of the lexical-semantic section, an independent t-test was administered. In the verbal fluency without constraint subtest, no significant effects of either age or education on the participants' performance were observed, indicating that the speech production ability of these two age groups is independent of age and educational level. Similarly, in the subtest of the verbal fluency with orthographic criteria (b), the effect of age was not significant in either educational group; however, education had a notable impact on the participants' performance. In the subtest of the verbal fluency with semantic criteria (clothes), no significant age effect was observed in either educational group, but the role of education was highly significant (p = 0.001) across both age groups. Finally, in the semantic judgment subtest, the effect of age was not significant in the group with less than 12 years of education. In contrast, it was significant (p = 0.05) in the group with 12 or more years of education. Overall, the findings demonstrate that higher formal education, particularly in areas related to speech production with orthographic and semantic criteria, exerts a more pronounced influence on the linguistic performance of the participants in this study. Conversely, aside from the semantic judgment subtest, the variable of age did not have a significant effect on the performance of the educated individuals.ConclusionBased on the results of this research, it can be concluded that the validity of all four subtests and the reliability of the semantic judgment subtest of the Persian version of the protocol for assessing lexical-semantic skills in healthy Persian-speaking adults are confirmed. Moreover, these findings reveal that the variable of educational level has a greater impact than the variable of age on the lexical-semantic communicative skills of the examinees across all subtests, except for the verbal fluency without constraint subtest. This is because the performance of the subjects with education at the diploma level and above was significantly better than the performance of those with less than 12 years of education. Finally, given that the scientific credibility of the Persian version of the Montreal protocol has been established as a standard, novel, and multidimensional tool for evaluating various communication skills, it can be utilized not only in diverse fields of research and clinical assessments of Persian-speaking patients, but also in scientific domains related to Persian language and teaching Persian to non-Persian speakers.

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