The Psychology of Love

A Preface

The information in this post comes in great part from A General Theory of Love1. This book plays a little fast and loose with certain psychological ideas, and in particular with the model of human brain structure. Of course, brain structure is complicated and messy, so just about any time you label and define some region of the brain you’re doing a simplification. However modern neuroscientists seem to think that for a simplification this model does a decent job. And this may remain a good model for a theory of love, because most of what’s since been discredited are its evolutionary claims about the order of development.

The Triune Brain Model

The Triune Brain Model divides the brain into 3 regions, based on distinctions in physical location and architecture, function, and “evolutionary age”.

The Reptilian brain is the oldest part of the brain. This is responsible for autonomic and instinctive function, i.e. breathing, heart rate, circadian rhythm, and reflexes. If one is brain dead but not dead dead, this is the region that’s still lit up.

The Limbic brain is the center for all things emotion, and is biologically unique to mammals. In the next section we will focus on this region.

The Neocortex is the newest part of the brain. This is where our ability to reason, plan, speak, and do other higher level thinking comes from. This is what makes humans so distinct from all other animals.

This physical and evolutionary distinction between the limbic and neocortical brain offer a partial explanation as to why emotionality and rationality are so often at odds. And contrary to what we (I) might like to think, thoughts have little power in affecting emotion…how often do you successfully talk yourself out of a feeling?

Limbering Up

According to Lewis, Amini, and Lannon, love isn’t just a feeling, but a connection between brains. Our limbic brain connects us with other mammals (particularly humans) in subtle, but incredibly influential ways.

Limbic Resonance is a process by which one can tune into another’s emotional state, and physiologically empathize. It affects us with varying degrees of subtlety. Consider Mood Contagion, for example. When you see some stranger laughing, it might brighten you up a bit. But when your best friend or significant other is laughing, it can be hard not to laugh with them. The authors argue that this is part of what gives concerts and movie theaters a special feel. It’s not just the big screen and the sound system, it’s everyone in the same room sharing in an emotion together.

A symphony of mutual exchange and internal adaptation whereby two mammals become attuned to each other’s inner states. It is limbic resonance that makes looking into the face of another emotionally responsive creature a multi-layered experience. Instead of seeing a pair of eyes as two bespeckled buttons, when we look into the ocular portals to a limbic brain our vision goes deep: the sensations multiply…When we meet the gaze of another, two nervous systems achieve a palpable and intimate apposition.

Limbic Regulation is the process of changing another’s physiology and vice versa. There are thousands of physiological parameters, (i.e. blood pressure, immune function, oxygen, sugar, hormone levels). And contrary to prevailing belief, there’s evidence that many of these systems are on open loops.

In the 40s, research was conducted on sterile nurseries—institutions for orphaned and babies and children. Back then, these nurseries thought it’d be a pretty good idea to minimize contact with and between children to minimize the spread of illness. The study found that children handled this way, despite having all their physical needs met, became withdrawn, weaker, and more sickly. At a time when the outside death rate from measles was 0.5%, the death rate for these children was 40%. The average death rate for all children in these institutions was 75%, and the more “sterile” the nursery, the higher the death rate.

At birth, the limbic brain is totally unregulated. Emotional responses are socialized, learned by watching and interacting with a parent. Though we’re most emotionally plastic in infancy and early childhood, we need stability and healthy connections throughout our lives. Positive limbic regulation is not emotional weakness or immaturity, it’s physiological necessity.

Because loving is reciprocal physiologic influence, it entails a deeper and more literal connection than most realize. Limbic regulation affords lovers the ability to modulate each other’s emotions, neurophysiology, hormonal status, immune function, sleep rhythms, and stability. If one leaves on a trip, the other may suffer insomnia, a delayed menstrual cycle, a cold that would have been fought off in the fortified state of togetherness.

Limbic Revision is the process of changing the structure of the limbic brain. This is the basis for psychotherapy. Significant changes can take years to set in.

In a relationship, one mind revises another; one heart changes its partner. This astounding legacy of our combined status as mammals and neural beings is limbic revision: the power to remodel the emotional parts of the people we love, as our Attractors activate certain limbic pathways, and the brain’s inexorable memory mechanism reinforces them. Who we are and who we become depends, in part, on whom we love.

Loving and Being in Love

Lewis, Amini, and Lannon draw a distinction between loving and being in love. When we’re in love, we have a burning passion for another. We might think we could never love anyone else like this, that we need to be physically close to them, and that nothing matters as much as this feeling. When these powerful feelings start to fade, we may have doubts about our love. Though valuable for a new relationship, being in love is just a preamble to loving. Loving is a much more sustainable feeling which is about long-term attachment. Loving is not always easy, it can require intention and maintenance, but this is not a bad thing. It’s a mistake to think that the passion of being in love can last forever, or that a relationship is bad because that passion has faded.

While one can be in love with someone who is not in love with them, loving must go both ways. In a mature loving relationship, each partner knows the other deeply, they can pick up on invisible signals sent by the other. They are “lymbically attuned”.

Thoughts on this Theory

This theory offers an explanation for increasing rates of emotions like loneliness, despite increasing means of communication. One may be able to communicate the same neocortical-level information over the phone, but the limbic brain is getting very little. These ideas also track with the emotional emptiness of materialsim. I.e., the unhappiness so many “successful” people feel despite their money, power, living comfort, or whatever.

An interesting implication of this theory, in particular of the importance of the limbic brain, relates to the question of whether sufficiently advanced AI could feel. Of course that answer is No, at least if they continue to be designed the same way. If the distinctions made between the limbic and neocortical systems are accurate, then there’s no necessary connection between emotion and rational intelligence.

It seems to be a fairly common mindset that emotional maturity and wisdom are emotional restraint; that the suppression of non-rational feelings is a valuable feature of civil society. But this theory says just the opposite. Whether or not it’s true that we’re too favoring of rationality over emotion, our perceptions of these things have far-reaching implications. They shape social norms that affect us all individually in subtle, murky ways2.


  1. A General Theory of Love (2000), by Thomas Lewis, Fari Amini, and Richard Lannon, professors of Psychiatry at UCSF.

  2. We live in a society.