The Psychological Domains: Learn It 2—The Biological Domain

The Biological DomainImage of five pillars, showing the biological, cognitive, developmental, social and personality, and mental and physical health.

What changes in your brain when you are angry, happy, hungry, depressed, or nervous? How is your brain sometimes tricked into seeing things that aren’t there? How much of your behavior is dictated by your genetics? These are questions considered within the biological domain.

biopsychology

The inside of a human brain
Figure 1. Different brain-imaging techniques provide scientists with insight into different aspects of how the human brain functions.

Biopsychology—also called biological psychology or psychobiology—applies the principles of biology to the study of mental processes and behavior. Researchers in this field explore how the nervous system’s structure and function influence thought and action.

Subfields of biopsychology include:

  • Behavioral neuroscience: links brain activity to behavior.

  • Cognitive neuroscience: studies brain processes underlying thinking, memory, and language.

  • Neuropsychology: examines brain injuries and disorders to understand brain–behavior connections.

 

Research areas span sensory and motor systems, sleep, drug use, reproduction, neurodevelopment, plasticity, and the biological basis of psychological disorders. This interdisciplinary field overlaps with neuroscience, drawing from biology, medicine, physiology, and chemistry (Carlson, 2013).

Evolutionary Psychology

While biopsychology often examines the immediate biological causes of behavior, evolutionary psychology focuses on the ultimate causes—how traits and behaviors evolved through natural selection.

evolutionary psychology

Evolutionary psychologists study the extent that a behavior is impacted by genetics. The study of behavior in the context of evolution has its origins with Charles Darwin, the co-discoverer of the theory of evolution by natural selection.

  • Just as organs like the heart and lungs evolved for survival, cognitive processes (e.g., memory, language, social behavior) also have adaptive functions.

  • Psychological mechanisms may have evolved to help humans find mates, cooperate, detect danger, form families, and navigate social groups.

Evolutionary psychologists test predictions by comparing behaviors across cultures. If a trait has a strong genetic basis, it should appear in all human groups.

Examples of evolutionary psychology research include:

  • Mate preferences: A study of 37 cultures found women valued earning potential in partners more than men, while men prioritized youth and attractiveness (Buss, 1989).

  • Friendship: Recent research shows men tend to value physical attractiveness in opposite-sex friends, while women emphasize protection and resources (Szymkow & Frankowska, 2022).

Sensation and Perception

Another key area within the biological domain is sensation and perception—the study of how we detect and interpret sensory information.

This field blends psychology, physiology, and neuroscience to explore how biological mechanisms of the senses (vision, hearing, touch, taste, smell, balance) connect to psychological experiences.

Example: Picture yourself on a busy campus—

  • Vision: colors of buildings, shapes of people walking past.
  • Hearing: laughter, footsteps, chatter.
  • Touch: the pressure of your backpack straps.
  • Smell: food trucks or freshly cut grass.
  • Balance & proprioception: your awareness of movement as you weave through the crowd.

All these sensory details illustrate how the brain integrates information to form a unified experience of the world.