Depression is a common and serious psychological disorder. It has many symptoms and is complex and variable, and the symptoms can vary greatly from patient to patient. Therefore, in the past, the medical profession usually summarized the clinical manifestations of depression as “three low symptoms”, namely “depressed mood”, “slowed thinking”, and ” The three aspects of mental activity (cognitive activity, emotional activity, and volitional behavior activity) are all diminished to varying degrees. The symptoms we mentioned in the previous article are the “three low symptoms” of depression. However, medical doctors later found that the typical “three low symptoms” of depression usually appear only in the more severe patients, but not necessarily in all depressed patients. Therefore, it is not appropriate to simply use the above “three low symptoms” to determine whether you or your family members are suffering from depression. It is now believed that the diagnosis of depression should focus more on the “core symptoms”. There are three core symptoms: depressed mood, lack of interest, and lack of pleasure. Depressed mood is better understood as a feeling of low mood, distress and sadness, pain and suffering, often sighing and sulking, or in severe cases, a feeling that life is worse than death. Lack of interest refers to patients’ significant decline or even loss of interest in their favorite activities. For example, some patients used to love playing basketball, but now they are not interested in playing basketball at all. Pleasure deficit refers to the depressed person’s loss of the ability to experience pleasure and to derive pleasure from the activities they normally engage in. Some depressed people are able to engage in activities such as reading books, newspapers, or watching television, but they do so mainly to pass the time or in the hope of being relieved from pessimism and disappointment, but deep down they have no feelings of pleasure. It is not difficult to identify some typical depressed people. Patients or family members can usually determine with some accuracy whether they are depressed by looking at the “three low symptoms” or “core symptoms” mentioned above. However, the majority of patients need to be diagnosed by a psychologist/psychiatrist. It is undeniable that until now, no objective tests for depression have been found in modern medicine, so the diagnosis of depression lacks effective objective laboratory tests and relies mainly on the clinician’s observation and judgment of the patient’s disease characteristics and pathogenesis. Although doctors often use some psychological tests to assist in the diagnosis process in order to facilitate observation and comparison, it is undeniable that the accuracy of the diagnosis of depression is still largely dependent on the clinical experience of doctors. Some patients are often “superstitious” about psychological tests, thinking that they can be used to diagnose depression. However, in reality, psychological tests, like other clinical tests, only play a supporting role in the doctor’s diagnosis. Some patients think that psychological tests have no role in the diagnosis of depression, or are not necessary. This view is narrow and one-sided. Psychological testing has a significant role in the diagnosis of mental illnesses (including depression). On the one hand, psychological tests can help doctors quickly obtain the psychological characteristics, personality tendencies and other psychological indicators of the tested person in a relatively short period of time, which can effectively avoid the problems missed by doctors due to neglect. On the other hand, psychological tests can be used to evaluate the severity and treatment effects of psychological disorders (including depression). However, it should be noted that the interpretation of psychological test results should not be directly applied, but needs to be thoroughly considered by a professional psychologist/psychosomatic physician in conjunction with the patient’s actual condition in order to reach a more accurate conclusion. Therefore, the role of psychological testing in the diagnosis of depression needs to be viewed objectively.