Psychopaths are often depicted as cold, unfeeling individuals with nerves of steel that are able to perform acts of immense cruelty without batting an eyelid. While this Hollywood-ized caricature is not entirely accurate – as there are in fact non-violent psychopaths – psychologists have tended to agree that an inability to feel fear is one of the major hallmarks of the condition. However, a new study in the Psychological Bulletin challenges this assumption, claiming that psychopaths can feel fear, but may have trouble sensing danger.

To conduct their research, the authors reviewed the existing studies on psychopathy, some of which date all the way back to 1806. In particular, they paid attention to how these studies defined the concept of fear, and how they tested psychopaths’ ability to feel it.

In doing so, they found that most of these studies don’t actually provide compelling evidence that psychopaths’ capacity to experience fear is impeded, largely because the variables they tested were not sufficient to fully examine this. Indeed, fear is a complex concept that consists of both a conscious experience element and numerous underlying cognitive mechanisms. According to the study authors, most previous research into psychopathy fails to examine both of these elements together.

For example, following decades of work, three major models of psychopathy have emerged. The first of these is known as the integrated emotion systems model, and states that deficiencies in a brain region called the amygdala impair recognition of sad and fearful facial expressions in other people, making psychopaths incapable of processing or responding to threats.

^{The amygdala is heavily involved in fear learning. Blamb/Shutterstock}

The response modulation hypothesis, meanwhile, holds that psychopaths are unable to process stimuli that would normally invoke a fearful response. Finally, the dual-process model states that while psychopaths are able to respond to dangerous or harmful stimuli, they are incapable of learning to associate these stimuli with these responses.

According to the study authors, all three of these theories suggest that psychopaths suffer from certain neurobiological defects that cause them to have trouble reacting to fearful events, but none actually examine whether or not psychopaths are capable of the subjective experience of fear.

Naturally, measuring subjective experiences is extremely difficult, as it can only be achieved by asking people to self-report on their own feelings. The researchers therefore went back over the existing literature on psychopathy in order to find studies that examine subjective experience, discovering that people diagnosed with psychopathy do in fact appear to feel fear, though they seem to have difficulty experiencing happiness and are often angry.

Based on these findings, the team suggests that psychopaths’ cognitive deficits are more relevant to the ability to process dangerous stimuli than the actual capacity to experience fear as an emotion.