Final answer:
June commits a central tendency error during the employee performance appraisal by rating most employees at the middle of the scale. This error hampers accurate performance assessments and may be alleviated by a thorough 360-degree review system.
Step-by-step explanation:
The employee performance appraisal situation described indicates that June commits a central tendency error when evaluating the employees. A central tendency error occurs when an evaluator rates most or all employees as average or around the middle of the scale, in this case, a score of 3 to 39 out of 50 employees. This type of error can diminish the effectiveness of the performance appraisal process by failing to accurately distinguish between high and low performers. Performance appraisals are more impactful when they incorporate a 360-degree system, which derives from a combination of ratings by supervisors, peers, the employee themselves, and occasionally outside observers, to provide a multifaceted view of performance and guide improvements.