Did you know?

Physician and neuroscientist Paul MacLean proposed that the human brain can be understood as 3 layers, known as the triune brain, also called the reptilian complex theory. In early evolution, humans relied on the “lizard brain” (reptilian brain) for basic survival instincts. Later, the mammalian brain (limbic system) evolved, adding emotions and social behaviors. This is then followed by the neocortex, responsible for higher-order thinking and reasoning—the brain as we know it today.

The lizard brain

Also known as the reptilian complex (R‑complex), the lizard brain governs basic survival functions and automatic behaviors. It is central to habitual and procedural memory—for example, the muscle memory that allows you to walk the same route to the bus stop without conscious thought.

This system enables rapid, instinctive responses critical for survival, such as fight-or-flight reactions, which were especially vital in early human evolution. While modern neuroscience views the triune brain model as an oversimplification, it remains a useful framework for understanding processes that operate largely on autopilot—fast, rigid, and highly conditioned, prioritising self-preservation over reflection or deliberate decision-making.

The mammalian brain

The mammalian brain (limbic system) plays a central role in emotional regulation, motivation, memory, and social behavior. Acting as a bridge between the reptilian brain and the neocortex, it translates primal, instinct-driven responses into more complex social and emotional behaviors.

Think of the nervous jitters we feel right before a big exam—that’s our limbic system in action.

The neocortex

The neocortex includes the frontal, parietal, occipital, and temporal lobes. It’s responsible for higher-order cognition, including reasoning, language, abstract thinking, and conscious decision-making. The neocortex is especially large in humans and other primates, supporting uniquely mammalian behaviors such as nurturing, caring for young, bonding, and play.

When we’re working on a group project and everyone huddles to brainstorm ideas, our neocortex kicks into action—analysing, reasoning, and generating ideas.

Implications for EQ

Although the reptilian complex is now considered an oversimplification of brain function, it remains a useful metaphor for understanding basic brain processes and how stress or trauma can trigger primitive survival responses.

In the context of emotional intelligence, the goal is for the brain’s instinctual, emotional, and rational systems—often referred to as the reptilian brain, limbic system, and neocortex—to work together effectively. A common challenge is that instinctual and emotional responses are faster than higher-order cognitive processes. In other words, we often react emotionally or instinctively before we think rationally.

While the brain doesn’t operate as 3 strictly separate systems, the triune brain framework helps illustrate that instinctual and emotional reactions are natural. Emotional intelligence doesn’t aim to suppress these responses; rather, it seeks to balance them with rational thinking to guide more effective behavior.

Developing EQ involves slowing down and giving our neocortex space to engage in decision-making. This allows us to shift from automatic reactions to more considered responses, integrating emotion with reason. With consistent practice, we can reframe the conflicts we face constructively, and be better able to control how we respond.

Contributed by Faith Phua for Break The Wheel.