But then I noticed something else. On the Big Five personality test, he scored extremely low in Compassion, a dimension of Agreeableness. Now, anyone that reads his books (his latest is "Hilarity Ensues") knows he's not known for his compassion. But I had empirical proof.

At the end of the interview, I jokingly told him to use his powers responsibly. But it did occur to me that maybe his lower levels of empathy, coupled with his heightened ability to read people may enable him to attain his goals. But this posed a dilemma, because the "Reading the Mind in the Eyes Test" is supposed to measure Theory of Mind, a uniquely human capacity to reason about the mental states of others. Some psychologists argue that this ability underlies our capacity for cooperation, harmony, and lasting friendships.

But his compassion and empathy levels are low. So I wondered: could the Reading the Mind in the Eyes Test be measuring a separate component of theory of mind-- perhaps a darker component that evolved for manipulative purposes?

***

Recently, psychologists have stepped outside of the clinical setting and have accumulated research on how the dark side of human nature varies in the general population. What has become quite clear is that the "Dark Triad," which consists of the combination of Machiavellianism (which involves interpersonal strategies for manipulating others), narcissism (which involves an inflated view of self-worth and grandiosity) and psychopathy (which involves deceit, high impulsiveness, recklessness, and manipulation regardless of the cost to others), is an overarching trait that everyone has to some degree. Some people just have a lot more of it than others.

The common thread running through all three traits is low empathy and low agreeableness. Still, the three traits are only moderately correlated with one another, and recently researchers have started to assess the independent predictions of each separately from the others, and how people with a different balance of the dark triad traits go about obtaining their goals differently (note: I gave Tucker a measure of the Dark Triad and he did not score high in psychopathy).

In a hot-off-the press paper in Personality and Individual Differences, Michael Wai and Niko Tiliopoulos looked at the empathic nature of dark individuals. They distinguished between two types of empathy: cognitive empathy and affective empathy. Cognitive empathy involves the ability to figure out the emotional states of others without feeling any emotional contagion (i.e., without being able to feel what they are feeling). In contrast, affective empathy involves sharing an emotional reaction in response to others' emotions. This form of empathy facilitates altruistic behaviors. Prior research shows that individuals with high-functioning autism are impaired in cognitive empathy, but do not differ from neurotypicals in emotional empathy. The exact reverse appears to be true for Dark Triad individuals.

The researchers had 139 university students complete personality measures of the Dark Triad, and they also gave them a test of empathy. In the empathy test, they had the students view a series of images of individuals with different facial expressions. For each picture they were asked to rate how they felt towards the person. This was their measure of affective empathy. They also had people select which emotions they believed each of the images expressed, and their answers were scored on how correctly they identified the emotion that was being expressed. This was their measure of cognitive empathy.

Those scoring high in narcissism, Machiavellianism, and psychopathy all reported a positive feeling when looking at sad faces. They seemed to actually be happy when others were sad. Interestingly, only narcissists were accurate at recognizing anger. Therefore, out of the three Dark Triad traits, narcissists appear to stand out as having enhanced cognitive empathy. This is interesting since recent research conducted by Peter Jonason, Glenn Geher, and myself suggests out of all the Dark Triad traits, narcissism is tied most heavily to extroversion and a desire to engage in social interactions. Perhaps their enhanced cognitive empathy facilitates superficial, short-term interpersonal interactions and relationships.

Clearly affective empathy is also extremely important for harmonious social interactions. So how can Dark Triad individuals obtain their interpersonal goals with this chip missing? The researchers argue that

"individuals high on the dark triad traits appear to exhibit an empathic profile that allows them to retain their ability to read and assess others’ emotions, and subsequently utilise this sensitive information to formulate strategies with which they can acquire what they want, while their lack of affective empathy may lead them to overlook or ignore potential harm inflicted to others in the process."

***

But there's more to this puzzle. If theory of mind evolved to facilitate harmonious social interactions, why do Dark Triad individuals score so high on the Reading the Mind in the Eyes test-- a capstone measure of theory of mind?

It turns out there are at least two main dimensions of theory of mind (ToM). The social-perceptual component of ToM involves the ability to determine the mental states of others using immediately available non-verbal cues (e.g., eyes, face, hand gestures). This maps on to the cognitive empathy component, and is what is measured by the Reading the Mind in the Eyes test. This component of theory of mind shows up earlier in development and is related to the right hemisphere medial temporal and orbitofrontal regions of the brain.

In contrast, the social-cognitive component of ToM (not to be confused with cognitive empathy) involves the ability to reason about the mental state of others, and use that reasoning to predict or explain their behavior. This ability involves inferring what others know or believe to be true apart from what you know or believe to be true. This is a later developing skill and is more strongly dependent on linguistic capacities. This component of theory of mind draws on left hemisphere circuitry involving medial frontal areas and the temporoparietal junction.

Daniel Nettle and Bethany Liddle found a relationship between the social-cognitive component of theory of mind, but not the social-perceptual component. It appears that the agreeable, compassionate, altruistic aspect of our human nature is only associated with the higher-level, social-cognitive component of theory of mind.

***

Now for the last few pieces of this puzzle.