"At fourteen, Amber could boast of killing her guinea pig, threatening to burn down her home, and seducing men in exchange for gifts. She used the tools she had available to get what she wanted, like all children. But unlike other children, she didn't care about the damage she inflicted. A few miles away, Lenny Skutnik cared so much about others that he jumped into an ice-cold river to save a drowning woman. What is responsible for the extremes of generosity and cruelty humans are capable of? By putting psychopathic children and extreme altruists in an fMRI, acclaimed psychologist Abigail Marsh found that the answer lies in how our brain responds to others' fear. While the brain's amygdala makes most of us hardwired for good, its variations can explain heroic and psychopathic behavior. A path-breaking read, The Fear Factor is essential for anyone seeking to understand the heights and depths of human nature"-- "When a dog ran in front of her car, Abigail Marsh swerved to avoid it. She next opened her eyes to see that she was stranded in the middle of the highway, facing oncoming traffic, and unable to restart her car. Just as she abandoned all hopes of survival, a stranger, at great risk to his own life, crossed the highway, got her car running, and brought her back to safety. For Marsh, this remains a revelation: much of social psychology depicts human nature as fundamentally selfish, cruel, and self-interested but here was a fellow human willing to help another with no benefit to himself. Why? In The Fear Factor, Abigail Marsh, now a psychology professor at Georgetown, provides the answer. By studying the brain of psychopaths and extraordinary altruists in an MRI, Marsh uncovered a surprisingly simple mechanism lying behind our capacity for empathy: the ability to recognize others' fear. Psychopathy, she discovered, is an inability to understand others' fear as well as to even recognize the feeling: one psychopath could famously only identify fear as what his victims looked like before he stabbed them. In turn, extraordinary altruists have stronger responses to others' fear, overturning the conventional cliché of the fearless hero. And altruism is not simply reserved for fellow humans. As Abigail Marsh walks us from one fascinating revelation to the next, we meet mother rats who risk their lives to rescue unknown pups; lions who take care of the children of their prey; and dogs who become the caretakers of orphan animals. Once you stop to look, examples of altruism are simply everywhere across the living world. A revelation, The Fear Factor is both a paradigm-shifting book on the heights and depths of human behavior, and an enthralling read filled with unforgettable stories"--