The “Halo Effect” is well-researched cognitive bias (see Wikipedia Page) which can affect people’s judgment in different situations. On a high level, the halo effect describes the tendency of evaluators to be influenced by previous judgments of personality or performance of an entity.
This bias may influence an examiner during the grading process. If the first exercise is solved well (badly) by a student, the grader will tend to award more (less) points than accurate for the other exercises of the student. This constellation may arise if the grader processes the exams sequentially student by student. The grader could also be influenced if he remembers older assessments of the student or contributions of the student in the course. This may arise if the answers are not anonymized.
Anonymity and a well-designed Grading Workflow would eliminate this bias.