Differential item functioning (DIF) occurs when individuals with similar abilities on a construct get different scores on specific test items that are not related to the construct. This is often due to the item format or wording, and can result in bias in the interpretation of scores. Content bias refers to the extent to which a test measures what it is intended to measure, while criterion bias occurs when the standards for success on a test differ for different groups of people. Motivation is not directly related to this type of bias in test scores.