In its rush for the next breakthrough, the field of psychiatry often discards older, effective treatments due to historical stigma. For instance, MAO inhibitors and modern, safer Electroconvulsive Therapy (ECT) are highly effective for specific depression types but are underutilized because of past negative associations, a phenomenon driven more by politics than science.

In a counterintuitive medical choice, some individuals with healthy but underperforming limbs (e.g., a twisted foot) fight to have them amputated. They recognize that a well-designed modern prosthetic can provide more mobility and a better quality of life than their natural, but chronically dysfunctional, anatomy.

Unlike external machines, implanting parts internally triggers the body's powerful defenses. The immune system attacks foreign objects, and blood forms clots around non-native surfaces. These two biological responses are the biggest design hurdles for internal replacement parts, problems that external devices like dialysis machines don't face.

Our nervous system is wired to gravitate towards familiar patterns, confusing them with safety. This is why people unconsciously recreate painful or traumatic childhood dynamics in adult relationships. It is a biological pull toward the known, not a conscious desire for pain, making it a cosmically unfair default setting.

Contrary to the economic theory that more choice is always better, people sometimes prefer fewer options. Removing a tempting choice, like a bowl of cashews before dinner, can lead to better outcomes by acting as a pre-commitment device, which helps overcome a lack of self-control.

Humans crave control. When faced with uncertainty, the brain compensates by creating narratives and seeing patterns where none exist. This explains why a conspiracy theory about a planned event can feel more comforting than a random, chaotic one—the former offers an illusion of understandable order.

Rather than hiding unsettling medical realities like tissue procurement, being transparent can demystify the process and build public trust. Acting secretive makes people assume there is something to hide, whereas openly explaining even 'gruesome' details can reassure the public and ultimately help an organization's mission, such as encouraging organ donation.

Emotions act as a robust, evolutionarily-programmed value function guiding human decision-making. The absence of this function, as seen in brain damage cases, leads to a breakdown in practical agency. This suggests a similar mechanism may be crucial for creating effective and stable AI agents.

A cognitive bias causes us to consistently underestimate how much we will enjoy a social interaction. This flawed prediction leads to choosing isolation (e.g., a night on the couch) over connection, even when socializing would be significantly better for our brain health and well-being.