Have you ever considered the terms optimism and pessimism, what they might mean and how they might change not only your own wellbeing but also your dog's.

Optimism and pessimism aren't just about being positive or negative. They're not about slapping on a smile or wallowing in misery.

They're about expectations. Specifically, your brain's default prediction about what's going to happen next.

When you face something uncertain, an ambiguous situation, an unclear outcome, a future event, your brain makes a prediction. 

It has to. 

That's what brains do. 

They're prediction machines, constantly running simulations about what's coming next so you can prepare.

Optimism means your brain's default prediction skews positive. When faced with uncertainty, your first instinct is "this might work out well."

Pessimism means your brain defaults to negative predictions. The same uncertain situation triggers "this probably won't go well."

And here's the thing, these aren't conscious. You're not deliberately choosing to expect good or bad outcomes. 

Your brain is running this calculation automatically, below your awareness, based on years of accumulated experience and neural wiring.

Whether we go down the optimism or pessimism route most often means we have a cognitive bias, an optimistic or a pessimistic one. 

Let's get specific about what's happening in your brain when you're being optimistic or pessimistic.

When you face an uncertain situation with optimistic expectations:

Your brain releases dopamine, creating feelings of anticipation and possibility. This triggers norepinephrine, sharpening your focus without anxiety. Endorphins provide a baseline sense of wellbeing. Serotonin stabilises your mood.

Meanwhile, your parasympathetic nervous system remains relatively calm. Your cortisol levels stay manageable. Your body interprets the situation as a challenge to approach rather than a threat to avoid.

This chemical environment supports learning, memory formation, and creative problem-solving. Your brain is literally better at finding solutions when it's bathed in these neurotransmitters.

When you face the same situation with pessimistic expectations:

Your brain triggers your HPA axis, your stress response system. Cortisol and adrenaline flood your system. These chemicals narrow your focus, speed up your heart rate, tense your muscles. Your body is preparing for danger.

This chemical environment is terrible for learning and problem-solving but excellent for immediate threat response. 

If you were facing an actual predator, this would be perfect. 

But if you're just facing an ambiguous email from a client, this cascade is creating suffering without purpose.

The wild truth is that this stress response can remain activated for days after a single stressful event in pessimists, while optimists' systems return to baseline much faster.

Dogs have this exact same system. 

The same cognitive bias, running the same calculations, producing the same chemical cascades.

When your dog encounters something ambiguous, an unfamiliar person, a strange object in the hallway, a new walking route, their brain makes a prediction about what's going to happen next.

The optimistic dog's brain predicts "this might be good." Dopamine starts flowing. Their body prepares for approach. Their tail wags. They move forward with curiosity and energy.

The pessimistic dog's brain predicts "this is probably bad." Cortisol rises. Their body tenses. They hang back, or bark, or try to avoid the situation entirely.

Same strange person. Same unfamiliar object. Completely different internal experience, driven entirely by expectations.

And just like in humans, these expectations shape how your dog moves through the world.

The optimistic dog takes social risks. 

They approach new dogs hoping for play. 

They investigate novel objects expecting discovery. 

When training doesn't go well, they bounce back quickly because their brain still expects that good things are generally possible.

The pessimistic dog plays it safe. 

They assume that unfamiliar dog might be aggressive. 

That novel object might be dangerous. 

When they fail at something, they give up more quickly because why waste energy on something that probably won't work anyway?

This is why some dogs seem "confident" while others seem "anxious" it's not really about confidence in the way we usually think about it. 

Bias is about what their brains predict will happen when they encounter uncertainty.

So we know the theory, let's get specific about how this plays out in everyday situations.

Your pessimistic dog sees another dog approaching on the path. Their brain predicts threat. 

Cortisol floods their system. Muscles tense. Heart rate spikes. They bark or lunge, not because they've made a conscious decision to be reactive, but because their body has prepared for danger based on their brain's negative prediction.

The same approaching dog, viewed by an optimistic dog, triggers a completely different cascade. 

Their brain predicts play. Dopamine flows. Their body prepares for social engagement. They pull towards the other dog with a wagging tail.

Neither dog is "right" about the approaching dog. They're both responding to their own internal predictions, not objective reality.

This is why reactivity is so difficult to train away with traditional methods. 

You're not fighting a behaviour problem. You're fighting a dog's deeply ingrained cognitive bias. 

Their brain genuinely expects bad things to happen, and it's preparing their body accordingly.

One thing I talk about a great deal is the importance of general and continuing education for dog professionals. 

Because if a dog trainer believes that the same training will work for every single dog, they may become frustrated when it doesn't. 

Trainer frustration can lead to compromises in the dog's welfare, like the use of suppression to change behaviour (think prong collars, overwhelm and shock collars) 

Yet with education and understanding we know naturally how to judge a dog's cognitive bias. 

And how to bring the pessimist around to more optimistic expectations. 

An optimist needs to be taught general life skills and they already feel pretty safe.

A pessimist needs to learn first that they are safe, a process that is worlds away from loose leads and recall. 

We also know that exposing a pessimist to more bad outcomes (the collars and overwhelm) creates more pessimism. 

And a good, educated dog professional will never do that. 

Just like in humans, optimism in dogs isn't just about behaviour or mood. 

It affects physical health in measurable, significant ways.

Research on optimistic versus pessimistic dogs shows striking patterns:

Optimistic dogs demonstrate:

• Lower baseline cortisol levels
• Better stress recovery (their cortisol returns to normal faster after stressful events)
• Stronger immune response
• Better resilience to illness
• More successful surgical and injury recovery
• Longer, healthier lives

How can a dog's expectations about uncertain situations affect their physical health?

But when you understand, it's perfectly logical.

Optimistic dogs experience less chronic stress because their brains aren't constantly predicting threat. 

They're not bathing in cortisol day after day, week after week, year after year.

Think about the pessimistic, anxious dog. 

Every car door slam is potential danger. Every unfamiliar person is a threat. 

Every change in routine triggers their stress response. Their body is living in a constant state of low-level emergency.

That means chronic cortisol elevation. And chronic cortisol does terrible things to bodies, canine or human. 

It suppresses immune function. It impairs digestion. It interferes with healing. It damages the cardiovascular system. It even affects brain structure over time.

The optimistic dog is  experiencing those same car door slams, unfamiliar people, and routine changes. 

But their brain is predicting "probably fine" rather than "probably dangerous." Their stress response isn't constantly activated. Their body gets to spend more time in rest-and-digest mode rather than fight-or-flight mode.

That difference, accumulated over years, has massive health implications.

As a dog guardian it's a good idea to learn what your dog expects from the World around them. Body language is recognisable and optimism is teachable. 

I show you how in my books and in my free reader community. Start by clicking my bestselling book below. 

Research: Parr-Cortes, Z., Müller, C.T., Talas, L. et al. The odour of an unfamiliar stressed or relaxed person affects dogs’ responses to a cognitive bias test. Sci Rep 14, 15843 (2024). https://doi.org/10.1038/s41598-024-66147-1