It is not linear, though a spoken sentence has conspicuous linear features and can often be profitably analyzed linearly.
It is a network where many parts connect robustly with other parts and where some parts connect only weakly. Unconnected parts can arise but usually they are rapidly incorporated into the network, even if only weakly, even if only to be rejected from it.
The mind in many ways resembles the system of language. Add semiotic codes and the resemblance grows stronger. Add random and not-so-random associations between semiotic and linguistic elements and the resemblance seems even better.
Emotions, except in their most primal form, have to be defined by language, semiotics, or associations to have impact or “meaning.”
Charles Peirce doubted the value of linear logical notation, preferring notation employing two or three dimensions. His existential graphs became the basis of model theory. (Interestingly, his work in this area was ignored until 1964, long after his death.)
While the human mind may be more than just a network, much about it can be explained by thinking of it as an associative network. While many mental associations are not logical, or even rational, in a formal sense, virtually all of them make subjective sense to the mind experiencing them. My associations with snow will be different from yours, but if we cared to we could compare them and come to a better understanding of each other.
A key to grasping how our minds work is to approach the very rich subjective network of mental associations—both logical and not—through the linearity of language, especially short bursts of language spoken in real-world situations.
Grasping our minds in this way probably cannot be done in a laboratory and outcomes will rarely, if ever, repeat themselves even outside of the lab.
Most science is based on repeatability and controls, such as a laboratory setting. Yet, clearly, not all investigations—even very rational, logical ones—can be pursued in those ways.
FIML practice uses the linear “logic” of short bits of real-world conversation to access the large associative network of the mind as it is actually functioning in a real-world situation.
In this sense, FIML practice does something that cannot be done in any other way. No theory can embrace everything you say and no theory can capture the complex interplay of feeling, speech, meaning, biology, and circumstances that actually comprise the most significant moments of our lives.
FIML, thus, is a sort of science of the moment, a shared science that allows two people to analyze their minds as they actually are functioning in the real world.