Psychologists study a wide range of topics related to human behavior and mental processes. They explore various domains that contribute to our understanding of human behavior, cognition, and emotions. The broad domains that can be studied by psychologists include:

1. Developmental Processes:
Psychologists study how individuals develop and change throughout their lifespan. They examine the physical, cognitive, emotional, and social changes that occur from infancy to old age. This domain focuses on understanding the factors and processes that shape human development and how individuals adapt to different life stages.

2. Biological Bases of Behavior:
Psychologists investigate the physiological and genetic factors that influence behavior and mental processes. They study the structure and function of the brain, the role of neurotransmitters, genetics, and other biological processes that contribute to behavior. This domain helps us understand the biological underpinnings of human behavior and mental disorders.

3. Social Bases of Behavior:
Psychologists explore how social interactions, relationships, and cultural influences shape behavior and mental processes. They study topics such as social cognition, attitudes, stereotypes, conformity, aggression, and interpersonal relationships. This domain helps us understand how individuals are influenced by the social environment and how they interact with others.

4. Cognitive and Affective Processes:
Psychologists investigate mental processes such as perception, attention, memory, language, problem-solving, decision-making, and emotions. They study how individuals acquire, process, store, and retrieve information, as well as how emotions influence cognition. This domain helps us understand how humans think, learn, and experience emotions.

By studying these broad domains, psychologists gain a comprehensive understanding of human behavior and mental processes. They often use a multidisciplinary approach, combining research methods and theories from various fields such as biology, sociology, neuroscience, and anthropology. This allows them to explore the complex interactions between biological, psychological, and social factors that shape human behavior.

In conclusion, psychologists study a wide range of domains including developmental processes, biological bases of behavior, social bases of behavior, and cognitive and affective processes. By exploring these domains, psychologists contribute to our understanding of human behavior, cognition, and emotions.