First, the top universities in psychology basically only recruit science students, such as Peking University, Zhong Da University and South China Normal University.
Second, psychology is a science, which needs strict scientific training, and needs to study anatomy, physiological psychology, psychostatistics, experimental psychology, psychometrics and other scientific courses during the undergraduate period. It is difficult for liberal arts students to master it well. Unless liberal arts students have the potential to learn science, they are not particularly biased.