Most management studies build upon generations of psychological research. Psychology, especially social psychology, can be defined as the study of people's thoughts, feelings, and behaviors in the presence of other people. Since most non-financial variables in management studies involve people's thoughts, feelings, or behaviors, these studies are using psychological science.
Absolutely. As mentioned by David, human resource management theories build upon psychological research.
Meanwhile, strategic management has drawn from assorted disciplines including physics and political science, but most of its theories are derived from economics, sociology, and psychology.
Agency theory and the resource-based view of the firm have economic roots while contingency theory and organizational ecology have sociological roots. Psychology has become more important source of ideas as researchers aim to understand strategic decision making and develop theories of behaviour strategy (Powell et al., 2011).
Some theories, such as Michael Porter's influential work on competitive strategy and competitive advantage, come almost entirely from one reference discipline (industrial economics) while others integrate multiple disciplines. Transaction cost theory has been characterized as "the ground where economics, strategy, and organization theory meet" (Rumelt et al., 1994).