Throughout (human) history, our brains have always responded to threats in the same ways - we are wired to survive, more than we are wired to think.
The amygdala is part of the brain responsible for heart rate, blood pressure, and breathing. It also regulates our emotions, specifically our fear response. When the amygdala senses danger, it sends a message to the adrenal glands to release adrenalin, which activates the body to prepare for danger. At the same time, cortisol is released as well, which is a neural inhibitor. This means it essentially shuts down the activity of the pre-frontal cortex, meaning it stops us from thinking clearly.
For early humans, the fight-or-flight response was vital.
The threat of physical harm was all too real. Today, however, our threats are more psychological, such as stress, financial pressures, work, and relationships. These social threats are perceived by our bodies in the same way as physical threats and this is why we are still reacting to these as though they were life-threatening attacks that require an instant fight, flight, or freeze response cutting off our rational thinking.
Cybercriminals know this and purposefully try to activate our amygdala to get us to do things, like clicking on a link. For example, they may contact you pretending to be from your bank warning you about a fraudulent transaction activating fear. Or they try to get you excited about an opportunity that’s too good to be true. Both of these could activate your amygdala flooding your executive brain. When we don't think critically, we give in to impulses that don't necessarily serve us. Like clicking on that link or handing over our OTP to the friendly stranger on the phone pretending to be from the bank.