  An individual's reaction time data to visual stimuli have usually been
represented in Experimental Psychology by means of an ex-Gaussian function
(EGF). In most previous works, researchers have mainly aimed at finding a
meaning for the parameters of the EGF function in relation to psychological
phenomena. We will focus on interpreting the reaction times (RTs) of a group of
individuals rather than a single person's RT, which is relevant for the
different contexts of social sciences. In doing so, the same model as for the
Ideal Gases (IG) (an inanimate system of non-interacting particles) emerges
from the experimental RT data. Both systems are characterised by a collective
parameter which is k_BT in the case of the system of particles and what we have
called life span parameter for the system of brains. Similarly, we came across
a Maxwell-Boltzmann-type distribution for the system of brains which provides a
natural and more complete characterisation of the collective time response than
has ever been provided before. Thus, we are able to know about the behaviour of
a single individual in relation to the coetaneous group to which they belong
and through the application of a physical law. This leads to a new
entropy-based methodology for the classification of the individuals forming the
system which emerges from the physical law governing the system of brains. To
the best of our knowledge, this is the first work in the literature reporting
on the emergence of a physical theory (IG) from human RT experimental data.
