Performance appraisals are a vital management tool that can go a long way towards keeping staff motivated, but they can lose much of their value - and indeed can work to lower office morale - if they are not carried out correctly. PERSONNEL management teachers consider performance appraisal programmes to be most important in motivating staff. While such programmes are valuable, there are four recurrent psychological processes that may detract from the usefulness of the appraisal system. The process of evaluating performance can have an emotional impact on a worker. Under certain circumstances, the evaluation may be seen as unfair and inaccurate. If so, the information from feedback is unlikely to be accepted. Furthermore, employees may not want to respond so realistic goals will not be set for performance appraisals perceived as more fair and accurate when: They are frequent; The supervisor helps to develop a plan for eliminating weaknesses; and The supervisor is perceived as having accurate knowledge of the subordinate's job duties and level of performance. Some appraisals are unreliable because supervisors' ratings are influenced by employees' unrelated words or deeds. For example, a supervisor may be biased by an employee's expression of job satisfaction. A supervisor who believes a subordinate is satisfied with his or her job will be more likely to give a favourable appraisal. In addition, the more satisfied an employee is perceived to be, the more likely the supervisor will be to recall the positive job-relevant behaviour of that employee. This distorted recall may unfairly influence the supervisor's appraisal. Frequently, both the supervisor and the worker dread performance feedback. The arbitrary nature of the information communicated in a performance appraisal contributes to this dread and causes an appraiser to be lenient. The appraiser's leniency may prevent performance appraisal programmes from being useful. Because supervisors do not know how to counsel their workers on low ratings, they would rather avoid the issue. Consequently, they usually give high ratings. Soon, everyone concerned realises that the process is little more than a ritual and it loses any value it might have had. Certain practices during feedback sessions may cause communication to break down. Supervisors often try to combine their critical comments with praise. Surprisingly, praise used to cushion criticism accomplishes little because it forms a ''praise/ criticism/praise sandwich''. In such a sandwich, the feedback session is begun by a few positive statements to ''put the employee at ease''. Then come the negative comments, followed by more positive comments, which merely signal that no other negative comments will follow. As a cushion for criticism, the praise loses its value. Usually there is a level of criticism that can be absorbed before an employee's defensive tendencies begin to appear. However, a supervisor's critical comments may, eventually, elicit defensive responses. The subordinate may tend to explain away deficiencies rather than face up to them. For feedback sessions to be effective: Supervisors should analyse their feedback style to identify such things as the praise/criticism/praise sandwich. These sessions should be a formal part of the system. Feedback from performance appraisals should be frequent enough to prevent an individual from being overwhelmed by too many negative comments at one time. D. J. Lam and C. H. Hui are principals in the Assessment and Development Centre, a consulting firm specialising in human resources management psychology. Enquiries may be directed to 810 0181 (tel) or 524 1128 (fax).