Final answer:
New recruits in law enforcement learn to control and hide their emotions through a process called depersonalization, which is a part of the broader concept of job burnout common in human service jobs.
Step-by-step explanation:
The practice where new recruits learn from police academy instructors, field training officers, and veteran officers to control and hide their emotions is known as depersonalization. This concept is part of the larger framework of job burnout, which is prevalent among human service professions, such as police officers. Depersonalization is characterized by an emotional detachment from the recipients of one's services, leading to callous or indifferent attitudes. This is one aspect of the three dimensions of job burnout; the other two being emotional exhaustion, where one feels psychologically drained, and a diminished sense of personal accomplishment in one's job-related achievements.