A major concern with the interview is that interviewer bias can distort the results. For example, a participant may perceive a smile or nod from the researcher as a sign of approval or encouragement to continue on the current topic. Thus, the participant's response may be influenced by subtle actions on the part of the interviewer. Although it is impossible to completely eliminate this problem, it can be limited if the interviewer maintains a consistent attitude throughout the entire interview. A common strategy is to adopt a universal, mildly positive response to anything the participant says.