Final answer:
The 1950s were a crucial decade for the emergence of themes such as group theory, relationships, and leader effectiveness in leadership research. Pioneers like Kurt Lewin laid the groundwork with their focus on leadership styles, group dynamics, and organizational psychology, influencing sociological and psychological theories about leader-follower dynamics.
Step-by-step explanation:
Group theory, relationships, and leader effectiveness were significant themes in leadership research that gained prominence in the 1950s. During this era, researchers like Kurt Lewin extensively explored the effects of different leadership styles, team structures, and group dynamics.
Lewin is often heralded as the founder of social psychology, and his contributions are heavily tied to the development of organizational psychology. His experiments involved observing children to study the effect of leadership style on aggression, group dynamics, and satisfaction, which had vast implications for the study of leadership in social groups.
Lewin’s work in coining the term group dynamics and in studying aspects such as group interactions, cooperation, and communication laid essential groundwork that shaped behavioral studies in organizational settings. The 1950s saw the evolution of sociological and psychological theory to include the study of structural-functionalism, a dominant force that started to wane in light of the need to understand the social changes occurring during that time, such as the Civil Rights movement and women's movement.
Additionally, the research style evolved to consider the bi-directional nature of leadership roles, acknowledging that different individuals might interact with leadership styles distinctly. Given this context, the 1950s were formative in developing our current understanding of leadership within groups and organizational psychology.