The scientific study of behavior and mental process of human is called Psychology.
Most psychologists would argue that the field should be receptive to a variety of viewpoints and approaches. Consequently, the phrase behavior and mental processes in the definition of psychology must be understood to mean many things. It encompasses not just what people do but also their thoughts, emotions, perceptions, reasoning processes, memories and even the biological activities that maintain bodily functioning.
Psychology most commonly defined at present as 'the scientific study of mind and behavior’. No dictionary on the subject is content to leave it there, however, and one such volume (admittedly with claims to being 'comprehensive') goes on and on about it for seven pages. But no definition of such an enormously wide-ranging subject will satisfy every psychologist. Indeed one dictionary claims that 'psychology simply cannot be defined'. My own opinion is that 'the scientific study of mind and behaviour' most accurately describes the route to increasing our psychological knowledge (behaviour) while it focuses on a psychological understanding of what that behaviour is about and how to make sense of it (mind).