There are several psychological theorists and researchers mentioned in the syllabus that you should focus on studying for the UPSC exam. These theorists and researchers have made significant contributions to the field of psychology and their theories are important to understand in order to have a comprehensive understanding of the subject. Here are some of the key theorists and researchers mentioned in the syllabus:

1. Sigmund Freud:
- Freud is considered the father of psychoanalysis.
- His theories emphasized the role of the unconscious mind and the importance of early childhood experiences.
- Key concepts include the id, ego, and superego, defense mechanisms, and psychosexual stages of development.

2. B.F. Skinner:
- Skinner was a behaviorist who focused on the role of reinforcement in shaping behavior.
- His theories of operant conditioning and the concept of positive and negative reinforcement are important to understand.

3. Jean Piaget:
- Piaget was a developmental psychologist who focused on cognitive development in children.
- His theory of cognitive development outlined different stages of intellectual development, including sensorimotor, preoperational, concrete operational, and formal operational stages.

4. Carl Rogers:
- Rogers was a humanistic psychologist who emphasized the importance of self-actualization and personal growth.
- His person-centered therapy approach focused on creating a supportive and non-judgmental therapeutic environment.

5. Albert Bandura:
- Bandura is known for his social learning theory, which emphasizes the role of observation and imitation in learning.
- His concept of self-efficacy, or the belief in one's ability to succeed, is an important aspect of his theory.

6. Erik Erikson:
- Erikson's theory of psychosocial development outlined eight stages of development, each associated with a specific conflict or challenge.
- His theory emphasizes the importance of social interactions and identity formation throughout the lifespan.

7. Lev Vygotsky:
- Vygotsky's sociocultural theory focuses on the role of social interaction and cultural influences in cognitive development.
- His concept of the zone of proximal development highlights the importance of providing appropriate support and scaffolding in learning.

Studying the theories and concepts put forth by these theorists and researchers will provide you with a solid foundation in psychology and help you answer questions related to various aspects of the subject in the UPSC exam.