I like thinking about what anatomical differences may contribute to personality type differences/emergence. For the ENFP I wonder if we don't have a higher than usual number of mirror neurons, or if these "mirror neuron regions" in our brains don't simply have more connections, and thus more influence, on the rest of our cognitive processes.
From Wikipedia
Mirror neuron - Wikipedia, the free encyclopedia (selections and emphasis mine):
A mirror neuron is a neuron that fires both when an animal acts and when the animal observes the same action performed by another.[1][2][3] Thus, the neuron "mirrors" the behaviour of the other, as though the observer were itself acting.
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Possible functions
Understanding intentions
Many studies link mirror neurons to understanding goals and intentions. Fogassi et al. (2005)[46]...
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Empathy
Stephanie Preston and Frans de Waal,[47] Jean Decety,[48][49] and Vittorio Gallese[50][51] and Christian Keysers[3] have independently argued that the mirror neuron system is involved in empathy. A large number of experiments using functional MRI, electroencephalography (EEG) and magnetoencephalography (MEG) have shown that certain brain regions (in particular the anterior insula, anterior cingulate cortex, and inferior frontal cortex) are active when people experience an emotion (disgust, happiness, pain, etc.) and when they see another person experiencing an emotion.[52][53][54][55][56][57][58]
However, these brain regions are not quite the same as the ones which mirror hand actions, and mirror neurons for emotional states or empathy have not yet been described in monkeys.
More recently, Christian Keysers at the Social Brain Lab and colleagues have shown that people who are more empathic according to self-report questionnaires have stronger activations both in the mirror system for hand actions[59] and the mirror system for emotions,[57] providing more direct support for the idea that the mirror system is linked to empathy.
Mmmmhmmmm...
Human self awareness
V.S Ramachandran has speculated that mirror neurons may provide the neurological basis of human self awareness.[60] ... Ramachandran gave the following explanation of his theory: “... I also speculated that these neurons can not only help simulate other people's behavior but can be turned "inward"—as it were—to create second-order representations or meta-representations of your own earlier brain processes. This could be the neural basis of introspection, and of the reciprocity of self awareness and other awareness. There is obviously a chicken-or-egg question here as to which evolved first, but... The main point is that the two co-evolved, mutually enriching each other to create the mature representation of self that characterizes modern humans." [61]
Fi baby all the way.
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Language
In humans, functional MRI studies have reported finding areas homologous to the monkey mirror neuron system in the inferior frontal cortex, close to Broca's area, one of the hypothesized language regions of the brain. This has led to suggestions that human language evolved from a gesture performance/understanding system implemented in mirror neurons. Mirror neurons have been said to have the potential to provide a mechanism for action-understanding, imitation-learning, and the simulation of other people's behaviour.[62]
We're supposed to have above average language abilities, and all the rest from above heh.
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Automatic Imitation
The term is commonly used to refer to cases in which an individual, having observed a body movement, deliberately performs a topographically similar body movement. Automatic Imitation rarely involves overt behavioral execution of matching responses.
Ok so we're supposedly good at making people feel comfortable. There's no debate about the fact that mirroring body movements is a great way to make others feel close and similar. And I don't know about you folks but this is not something that I TRY to do.
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Theory of mind
In Philosophy of mind, mirror neurons have become the primary rallying call of simulation theorists concerning our 'theory of mind.' 'Theory of mind' refers to our ability to infer another person's mental state (i.e., beliefs and desires) from experiences or their behaviour. For example, if you see a girl reaching into a jar labeled 'cookies,' you might assume that she wants a cookie and believes that there are cookies in the jar (even if you know the jar is empty).
:happy: ENFP's are supposed to be exceptional at "just knowing" the motivations of others.
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Gender differences
The issue of gender differences in empathy is quite controversial and subject to social desirability and stereotypes. However, a series of recent studies conducted by Yawei Cheng, using a variety of neurophysiological measures, including MEG,[94] spinal reflex excitability,[95] electroencephalography,[96][97] have documented the presence of a gender difference in the human mirror neuron system, with female participants exhibiting stronger motor resonance than male participants.

Yep...