"Altruism" in the brain

3 minute read

One of those impressively short brief communications in Nature Neuroscience by Dharol Tankersley et al. claims to have spotted a brain correlate of altruism:

Although the neural mechanisms underlying altruism remain unknown, empathy and its component abilities, such as the perception of the actions and intentions of others, have been proposed as key contributors. Tasks requiring the perception of agency activate the posterior superior temporal cortex (pSTC), particularly in the right hemisphere. Here, we demonstrate that differential activation of the human pSTC during action perception versus action performance predicts self-reported altruism.

I'm more interested in the "agency" part than the "altruism" part -- there is so much ambiguity about how "altruism" should really be defined. In this case, the mental task involved playing a computer game for charity.

But there is a literature associating the perception of agency with the posterior superior temporal cortex:

Perceptual models suggest that an early-developing and rudimentary capacity to perceive another agent's action as self-generated and goal-oriented may form the basis of empathic perception and, in turn, altruism. Neuroimaging studies indicate that brain regions in the pSTC contribute to the perception of agency. Both low-level perceptual tasks, such as target detection and prediction of complex movements, and more complex tasks, such as consideration of other agents' beliefs or (inter)actions in the environment evoke activation in the pSTC. For example, right pSTC activation increases when people watch geometrical shapes performing seemingly purposeful acts, but not when the shapes move at random. The pSTC may support rudimentary computations about the meaning of perceived actions, which might in turn subserve more complex social capacities, including empathy and theory of mind. Thus, the functional integrity of the pSTC may be a prerequisite for prosocial traits such as empathy and altruism.

The cited paper by Castelli et al. (2000) seems helpful:

We report a functional neuroimaging study with positron emission tomography (PET) in which six healthy adult volunteers were scanned while watching silent computer-presented animations. The characters in the animations were simple geometrical shapes whose movement patterns selectively evoked mental state attribution or simple action description. Results showed increased activation in association with mental state attribution in four main regions: medial prefrontal cortex, temporoparietal junction (superior temporal sulcus), basal temporal regions (fusiform gyrus and temporal poles adjacent to the amygdala), and extrastriate cortex (occipital gyrus). Previous imaging studies have implicated these regions in self-monitoring, in the perception of biological motion, and in the attribution of mental states using verbal stimuli or visual depictions of the human form. We suggest that these regions form a network for processing information about intentions, and speculate that the ability to make inferences about other people's mental states evolved from the ability to make inferences about other creatures' actions.

That study is the one with the moving geometric shapes. It includes a short section of the discussion on the superior temporal region, including this passage:

Puce et al. (1998) found increased superior temporal sulcus activation when viewing faces in which eye gaze repeatedly changed direction, and faces in which the mouth opened and closed. Similarly Calvert et al. (1997) observed increased activation in a region of the superior temporal gyrus during silent lip-reading of numbers versus still lips, and Grezes et al. (1999) reported activation of the superior/middle temporal region during viewing of meaningful hand gestures with tools and objects compared to stationary hands. Taken together these studies implicate the superior temporal sulcus and adjacent cortex in the perception of a variety of human body movements. This region is anterior and superior to the visual motion area MT/V5 (Puce et al., 1998), indicating that these activations are not attributable to movement per se. It is notable, too, that all our animations (including Random) displayed self-propelled movement as might be expected of animate agents. Our triangles, when described as moving purposefully and intentionally, activated the key brain regions that have been activated by viewing biological motion. Human-like face or body characteristics thus do not appear to be necessary to trigger the attribution of mental states. Future investigations are needed to clarify what particular properties of biological motion are functionally associated with temporoparietal activation, and whether distinct regions respond preferentially to specific visual attributes of biological stimuli (Castelli et al. 2000:321).

True enough, and isn't that interesting. Our interpretation of intent and agency filters through a perception system that doesn't care if the actor is human or not.


Castelli F, Happé F, Frith U, Frith C. 2000. Movement and mind: a functional imaging study of perception and interpretation of complex intentional movement patterns. NeuroImage 12:314-325. doi:10.1006/nimg.2000.0612

Tankersley D, Stowe CJ, Huettel SA. 2007. Altruism is associated with an increased neural response to agency. Nature Neurosci (online early) doi:10.1038/nn1833