a study of non-native persian language learners’errors in sentences containing negative polarity items

negation has many complicated forms and can be represented in a variety of ways. some sentences have explicit negation items and some other sentences convey the notion of negation without having any explicit negation item. negative polarity items (npis) are expressions that need to a negative context to be grammatically correct, and their meanings are compatible with negative sentences and are only used in some special sentences. learning such categories for non-native persian language learners is quite difficult, because of the difference between grammar of their mother tongue and that of persian language. although in the recent decades, in the field of second language studies, many researches have been done, there was not enough concentration on the application of npis by second/foreign language learners. the present paper aims to study and analyze the differences between the errors made by non-native persian language learners when comprehending or producing sentences containing npis. to do this research, after selecting 46 adult learners at random, they were tested within two groups and they answered a questionnaire contained 20 sentences. then, the errors made by them were carefully studied and comparison between the two groups, considering the difference in the standard deviation, showed a meaningful distinction between the errors of the two groups. the average score of the first group was higher than the second and the standard deviation was smaller. findings of this research suggest that the two groups made different errors.