自然手語是聾人社群間使用的手語，是一種善用空間性的視覺語言，文法手語則是混合視覺空間特性與聽覺序列特性的人工手語。先前研究發現，聾生對於自然手語的故事理解優於文法手語，本研究旨在探討構詞及句法因素是否即是造成文法手語理解困難的原因。實驗一操弄文法手語的構詞方式，依其與自然手語的關係分為借用、贅加與串接，結果發現聾生對於以贅加或串接方式構成的詞彙理解不如借用方式；實驗二操弄句子的空間特性，結果發現喪失了空間性的文法手語方位詞會造成句意理解困難。因此結論文法手語在構詞及句法上採用口語（中文）的序列性，喪失了手語的空間視覺優勢，會造成接收者的混淆，值得教育家進一步加以探討和改良。

It is common for teachers of the deaf to assume that Manually Coded Chinese （MCC） facilitates the learning of Chinese. But it is difficult for deaf students to understand MCC. Asking the question as to why understanding MCC is so difficult for deaf students, this study investigated the role of morphological and syntactic factors in MCC comprehension. It was found that the MCC words borrowed from natural Taiwan Sign Language are much easier to understand than words of the affixation or compound type. In addition, MCC sentences that preserve spatial syntactic features were easier to understand than sentences that do not. It was concluded that the reason why deaf students have difficulty in understanding MCC is that MCC does not take advantage of the visual superiority of natural sign language. The educators of deaf students must pay more attention to this phenomenon.