The example:
I see an apple juice carton. Sighing that I am thirsty, I reach towards it in order to drink from it, my fingers closing round it. Shortly, I insert a straw and suck.
The human anthropologist / psychologist understands my sigh and predicts that as a rational agent no doubt owning the carton of juice, I will deliberately drink it. He / she thus rationalises the use of straw and sucking.
The Martian neuroscientist monitors the light waves entering my eyes and my bodily hydration levels. Scanning the electronic structure of my brain, it predicts the neurons that will fire, their effect on my muscles and hence the movement of my arm in the direction of the juice and then, similarly, the following bodily events.
Assuming that human action is caused – proximally at least – by changes within the brain and body – there is no direct mediation of a Cartesian soul on my body - would any explanatory power be lost by sticking to the Martian perspective?