This article is an EEG/ERP study based on psycholinguistic models of reference resolution to study the discourse comprehension and coherent contexts through co-referencing between an anaphor and its antecedent in the same spoken context. How brain is able to establish reference between an anaphor and potential antecedents in discourse has become of great interest. Based on Informational Load Hypothesis by Almor (1999), an auditory task using participants with no neurological or medical disorder was designed to compare coreference resolution of a referential pronoun and its acceptable antecedent in two-sentence discourse context. Based on this theory, and considering the morpho-syntactic limitations of Persian language for processing the information comes from the pronominal anaphor, discourse function and processing cost of reference resolution analysis was examined by situations such as ambiguity in referring expressions. Research method in this study is based on psycholinguistic experimental model which indicates the sub-processes of brain functions responding to co-reference resolution. The model used in this research represents the balance between discourse function and processing costs of reference resolution between referential coherence and referential ambiguity conditions. The ERP components shown in this project indicate that the processing of anaphor resolution in different situations imposes different processing cost on working memory. The two components Nref and Left Anterior Negativity (LAN) in frontal lobe were elicited during referential ambiguity of the pronominal anaphor (third person) which has no gender feature. Nref is a sustained referential negativity which indicates the ambiguity of the referring anaphor. (LAN) in previous researches has shown the increasing activity of working memory. This result which is incompatible with previous studies, has indicated that lower salience of the antecedent can cause higher processing cost for the working memory in order to establish a cross-reference bridge between the new information and the already existing representations of antecedent.