How often would you say your decisions are influenced by emotion? Some studies have estimated around 90% for the average person. But that can't be right - surely we would notice that almost all of our decisions were shaped by our emotions in some capacity?

Let's reframe what emotions are. We know them as happiness, sadness, disgust etc. But beyond the surface, they seem to be an unconscious response to an experience. In a road accident, you'll see anger. When watching a scary movie, fear. These are simple fight or flight responses to experiences. In the modern day however, experiences are way more complex. Along with anger, you will also see dread - who's gonna pay for the damage to the car?

Emotional responses are layered and confusing, they are often invisible to us. Learning to recognise them can be a superpower. Not a power over people, but over yourself. I've battled with them for a long time, and I'll share what that's unlocked for me.

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Primal vs Modern Emotional Responses

We'll start by getting into what emotions are, and how our brains, and therefore our emotional responses have evolved. There are loads of models that theorise how our brains have evolved. The Triune Model says that there are three distinct layers to our brain. The neocortex, the outermost layer, is responsible for higher-order functioning like language, rational thinking, and episodic memory (memories of events). The innermost layer is the reptilian brain, which controls basic survival like breathing, heart rate etc. Then we have the emotional limbic system which sits in the middle, like the awkward middle child (I'm one, I know what it's like). Although the Triune model is seen as outdated, the foundation is there - our brains have adapted to accomodate new functions over time. I'll be using the 'limbic system' as a metaphor for emotional response handling in the brain.

Back in the day, life was simple. Go out, get food, bring back food, eat and celebrate, sacrifice to the gods, go to sleep. How many emotions would be involved in life back then? Maybe 8 or so - happiness, sadness, anger, fear, acceptance, loss, surprise, disgust. There were only so many opportunities for emotions to take place, so emotional responses would generally fall under one of a few. Fast forward to now, where there are so many opportunities that it's overwhelming. Emotions have gone from primal reactions to layered responses. Let's compare a threat from a predator in both time periods as an example:

1 Million years ago

The "upright man", or homo erectus if you're feeling fancy, is one of our earliest relatives to have human-like body proportions. They invented stone tools for hunting, but lacked the ability to create verbal language due to unsupported respiratory muscles required to produce speech. Communication would have been created via gestures, noises and context. We can assume that the upright man would likely have been a part of a hunting party, based on fossil evidence of persistence hunting and social coordination.

A predator in this case would have simply been a large or deadly animal. When faced with a threat to their life, core emotions would have been fear and anger.

Now

With societies as dense as ours, it is easy to feel isolated. Urbanisation and high population density have replaced small community structures and close relations. Larger societies means that we don't face predators in the traditional sense often. Very rarely do we find ourselves fighting for our lives, but adrenaline responses still occur. The stakes are much lower now.

A predator is not a threat to survival anymore, it is a threat to status. A manipulative partner, who systematically dismantles your self-worth and social connections would create feelings of fear and anger. But there's more to it. On top of those, it would layer shame, guilt, resentment and chronic anxiety.

Differences

Primal reactions, or primary emotions, are brief and fade naturally. They often fade after around 90 seconds. Side note: If you are feeling a primary emotion, try waiting 90 seconds or so for it to pass before acting. More on this in the 'My Experience' section. Some examples of primary emotions are:

• Joy
• Sorrow
• Fear
• Anger
• Disgust

Secondary emotions are the defense mechanisms, and are layered on top of the primaries. They are often delayed, and can become chronic if long-lasting. It is vital to learn to identify secondary emotions for emotional processing, as they obscure what is really going on under the hood. When you feel anger, you may then feel hostile or irritated. Some examples of secondary emotions:

• Joy -> Optimism
• Sorrow -> Depression
• Fear -> Insecurity
• Anger -> Hostility
• Disgust -> Avoidance

Sadly, primary emotions aren't going anywhere. They are completely natural on their own, and must be accepted. However, learning to separate primary from secondary emotions is the key to recovering from emotional distress. Secondary emotions are learnt, which means they can also be unlearnt.

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Physiological Responses

We've established that secondary emotions are learnt defense mechanisms. But why do we actually feel emotional responses? First, let's talk about how we feel it.

When you encounter something, there are two main processes that occur in the mind:

• Emotional processing - Have I seen this before? How did this make me feel then?
• Rational processing - Do I need to act? What would happen if I did or didn't?

If you've experienced it before, your brain will remember how you felt and produce a response accordingly. It releases specific chemicals, which bind to receptors in order to force certain neural firing patterns. Then you will feel the emotion. For an example, we will use the most well known chemical messenger, adrenaline. It activates the "fight or flight" response as we all know. Your brain has noticed a threat, and releases adrenaline to tell the rest of your body to respond to the threat. It is both a hormone and a neurotransmitter.

Chemical Messengers

Hormones are chemical messengers that change our bodily functions, like increasing heart rate or releasing energy. It's our brain's way of telling our body what needs to be done. They are produced by the glands as part of the endocrine system to travel through the bloodstream, making sure everything gets the message. Using adrenaline as the example, the hormone triggers changes like an increased heart rate and blood pressure, and redirects blood toward the essentials like muscles and the brain. This is why we may feel sick after an adrenaline rush, because our blood has been diverted away from the digestive system. Basically, it is an emergency override, forwarding all resources to essential functions. Hormonal imbalances are linked to conditions like diabetes and PCOS, and can cause symptoms like irregular periods, weight gain and difficulty sleeping.

Neurotransmitters are also chemical messengers, but they occur within the brain and nervous system. They are much faster than hormones, and are crucial at getting the message to where it is needed rapidly. They create either excitatory actions (promoting nerve firing), inhibitory actions (calming nerve activity) or modulatory actions (influencing the effects of other chemical messengers). Essentially, neurotransmitters allow neurons to communicate with each other, which is how our bodies do everything. Adrenaline as a neurotransmitter regulates processes like metabolism, focus and panic.

So, once the chemical messengers have been released, we experience an emotion. There isn't a specific chemical that creates "anger", rather an array of many chemicals working together that we label as anger. We know what the emotion is due to context. Different contexts can produce the same chemical responses, but we establish the differences rationally. The response we feel when anxious is the exact same response as excitement. Faster heart rate, sweaty palms, arousal. We know the difference because of the context.

Emotional processing happens regardless, and they are based on the primary emotions. Rational processing creates the secondary emotions. We can reframe our rationality to align with our values, but what is important to know is that the primary emotions will create a bodily response. This is ingrained in us, it is an instinctual response. All we can do is accept this, and rationalise our response.

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Complexity by Environment

Emotional complexity seems to scale depending on a species' role in an environment. The most emotionally complex animals are almost all highly social. Elephants, corvids, primates, humans. The demands of navigating a social hierarchy, tracking relationships, detecting betrayal, managing alliance and feeling empathy, require emotional granularity that solitary animals simply don't need. Tigers need emotions for threat, safety and hunger. A chimp needs all that plus jealousy, gratitude, shame and political awareness.

Though it is not just social group size that explains emotional complexity:

1. Long-term dependency relationships - Species where offspring require extended care (mammals especially) need attachment systems. Love, separation anxiety and grief are essentially the emotional hardware that keeps parents investing in their child over years. The longer the dependency, the richer the attachment emotion needs to be.

2. Cooperative hunting or problem solving - Species that need to coordinate with non-kin (wolves, orcas, humans) require a richer signalling system for intent, trust and role. Emotion becomes a communication protocol as much as an internal state.

3. Environmental unpredictability - Stable niches favour efficient, hardwired responses. Unpredictable, complex environments favour flexible emotional systems that can be tuned by experience rather than fixed by genetics. Emotion is partly the mechanism for personalising a general-purpose brain to its specific history.

But we will focus on social group size for now. To make this concrete, let's compare two animal orders, and their emotional complexities with their social structures.

The humble primate vs the flesh-eating (literally) carnivora.

Primates are almost always in a social structure. They know who the big dogs monkeys are and behave according to their roles and hierarchy. Whereas carnivores are mostly solitary - they usually hunt alone or in pairs. So primates and carnivora are on opposite ends of the social group size spectrum. Now let's take a look at their emotional complexity. At the most basic level, both orders experience fear, pleasure, social bonding. This makes sense, as they are both tied to survival and cooperation. But where they diverge is in the more cognitively demanding layers. Higher emotions like consolation, equity and delayed gratification are evidenced in primates. Carnivores don't need all this. They have a much smaller social structure, so they wouldn't need all of that. Niche demands are what create emotional complexity. Smaller demands, common in solitary species means less reliance on others for what they need. Higher demands promote a tribal, or communal hierarchy.

Social group size does definitely expand emotional complexity. Deeper though, niche demands in an environment is what creates social hierarchy. Humans have evolved to be immensely smarter than any other animal due to the demands of our survival, and we have the largest social structure by the same magnitude. For us to become as intelligent as we are, is it fair to say that emotion has played a crucial role?

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Emotion in the Core Decision-making Loop

Now that we know what emotions really are, we can get back to the topic of the role that emotions play in intelligence and decision-making. In any decision-making system, there are five major stages:

• Sense - Take in signals from the environment - light, sound, chemical gradients, data, language. Every system, from a bacterium to a human to an AI, has some form of input channel. Even the simplest organisms "sense" via chemical receptors.

• Model - Build an internal representation of the world. This is where cognition begins to separate simple from complex systems. More sophisticated brains construct richer internal models - predicting what will happen next, simulating outcomes, holding context across time.

• Evaluate - Compare options against some goal, value or survival signal. In biology this is reward/threat circuitry (dopamine, cortisol etc.). In AI this is loss function or reward model. Every decision-maker needs a criterion - without one, there's no basis for choosing.

• Act - Commit to a behaviour - movement, speech, a chemical release, writing a response. Even "do nothing" is a choice.

• Update - Compare the outcome to the prediction. Was the model right? Did the action achieve the goal? This is where learning happens - in neurons (synaptic strengthening), in evolution (generational selection), or in machine learning (backpropagation).

I touched on AI there, but more on that at another time. In biological, high-functioning systems, we can rationally add emotion to every stage of the loop:

• Sense - Emotion shapes what gets noticed. A fearful animal doesn't perceive its environment neutrally - threat-relevant stimuli are amplified before conscious processing even begins. The amygdala can trigger a fear response faster than the cortex can identify what caused it. So emotion is already acting as a perceptual filter.

• Model - Emotion colours the internal world model. An anxious organism models the future as more dangerous. A contented one models it as more relaxed. Mood literally changes the predictions a brain generates, not just how it responds to them. This is why depression is so debilitating and misunderstood - it corrupts the model, not just the motivation.

• Evaluate - The core function of emotion is to assign value quickly without exhaustive reasoning. Damasio's somatic marker hypothesis explains this - he found that people with damage to the emotional centers of the brain become worse decision-makers, not better, even with sound logic. Without emotional tagging of outcomes, every option looks equally weighted. Emotion acts as a load-bearing infrastructure.

• Act - Emotion provides the motivational energy to actually execute. Knowing what to do and having the drive to do it are separate systems. Apathy and depression cause the system to fail - the model and evaluation may work fine, but the emotional push to act is absent.

• Update - Acting as a feedback signal. Regret, satisfaction, shame, pride - these are the pillars of social learning. Without them, outcomes don't stick. Emotional valence of a result is what makes it memorable and what adjusts future behaviour.

When we make decisions, we think logically and rationally. But in order for us to do so optimally, emotion comes into play. Emotion acts as a kind of infrastructure, or operating system for the nerds like me. It reduces cognitive load by preprocessing stimuli through mental schemas. We don't have to worry about why we should be doing something, in the grand scheme of things. All we know is that things feel good, bad or scary.

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How I applied some of this to myself

I've dealt with OCD my whole life, of course I didn't know what it was back then. OCD has a way of preying on insecurities, shames and fears and turns them into compulsive behaviours to remind you that you are a good person. Rationally, I am a good person, I say my pleases and thank yous. But the lesser parts of me that I dislike, they get dug up and brought front and center. That was the problem - I buried them.

Compulsions in this sense are a kind of secondary emotion, a defense mechanism like we established. Defense mechanisms are just our way of coping with uncomfortable feelings. To truly rid ourselves of disorders like OCD, Depression, or GAD, we need to adjust our mental frameworks. Accepting uncomfortable feelings and changing the behaviours that we rationalise will lead us on a better path.

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TL;DR

Emotions are far more than feelings - they are the invisible infrastructure behind how we think, decide and learn. What started as simple survival responses have evolved, alongside our social complexity, into layered systems that filter what we notice, shape how we model the world, and drive us to act. Far from being the enemy of rational thought, emotion is what makes intelligence possible in the first place. Learning to tell your primary emotions apart from the secondary ones you've built around them is where the real self-awareness begins.

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If you liked this, then please let me know! Or if you have any suggestions, feedback or inquiries, all is appreciated.