In the past, large-scale, standardized testing organizations have implemented language assessments aimed at assessing the English language proficiency of students intending to study in education superior. These high stakes tests play a vital role when decisions made about individual performance and its result are considered as a diagnosis of the test takers' abilities. Among these performances, the International English Language Testing System (IELTS) writing score is considered by most universities to be a benchmark against student success in higher education. This has increased the concern of non-native raters (NNS) about the reliability and their consistency in assessment scores in countries where these tests are adopted. Although these NNS evaluators are not qualified as IELTS examiners, they are attending IELTS preparation language courses in these countries. In compensation to assessment, the curriculum of such courses is shaped by how assessors perceive the assessment criteria. Various factors underlying the variabil- ities in NNS rater evaluation include rater characteristics such as experience, background knowledge, and cultural background. Recent studies have stated that raters' ego, style and their intellectual ability to memorize can be considered the different actions of raters during the rating process (Lumeley,2002; Wiseman, 2012). However, the rating evaluation process was suggested by Barkaoui (2010), according to which rating is a decision-making process that evolves the interaction between the rater and also the rating scales. Therefore, its influence on raters' behavior, due to the variety of scales used in different tests and raters' individual differences in interpreting the scales, may interfere with how they derive a score. This article aims to review studies of...... half of the article ......SL Essay Evaluation: The Influence of Sentence Level and Rhetorical Features. Journal of Second Language Writing P, 3-17.McNamara, T., & Roever, C. (2006). Validity and social dimension of language tests. Language Learning, 56, 9-42. Upshur, J. A., & Turner, C. E. (1999). Systematic effects in the assessment of ability to speak a second language: Test method and student speech. Language Testing, 16(1), 82–111.Weigle, S.C. (2002). Evaluate writing. Cambridge: Cambridge University Press. Winke, P., Gass, S., & Myford, C. (2011). The relationship between the study of raters' prior language and the evaluation of foreign language speech samples. TOEFL iBT® Research Report. Princeton, NJ, Educational Testing Services. Wiseman, C. S. (2012). Evaluator effects: Ego involvement in the evaluator's decision-making process. Evaluate writing, 17(3), 150-173.