"It was (and is) common to think that other animals are ruled by "instinct" whereas humans lost their instincts and are ruled by "reason," and that this is why we are so much more flexibly intelligent than other animals. William James took the opposite view. He argued that human behavior is more flexibly intelligent than that of other animals because we have more instincts than they do, not fewer. We tend to be blind to the existence of these instincts, however, precisely because they work so well—processing information so effortlessly and automatically. They structure our thoughts so powerfully, he argued, that it can be difficult to imagine how things could be otherwise. As a result, we take "normal" behavior for granted. We do not think that "normal" behavior needs to be explained at all. This "instinct blindness" makes the study of psychology difficult. To get past this problem, James suggested that we try to make the "natural seem strange". "It takes...a mind debauched by learning to carry the process of making the natural seem strange, so far as to ask for the why of any instinctive human act.” Evolutionary Psychology: A Primer

"Many psychologists avoid the study of natural competencies, thinking that there is nothing there to be explained. As a result, social psychologists are disappointed unless they find a phenomenon "that would surprise their grandmothers," and cognitive psychologists spend more time studying how we solve problems we are bad at, like learning math or playing chess, than ones we are good at. But our natural competencies—our abilities to see, to speak, to find someone beautiful, to reciprocate a favor, to fear disease, to fall in love, to initiate an attack, to experience moral outrage, to navigate a landscape, and myriad others—are possible only because there is a vast and heterogeneous array of complex computational machinery supporting and regulating these activities. This machinery works so well that we don't even realize that it exists. We all suffer from instinct blindness. As a result, psychologists have neglected to study some of the most interesting machinery in the human mind." Kathy Kolbe, Powered by Instinct

From Plato and Aristotle in ancient times, to McDougle, Maslow and Kolbe in modern times, the discussion of the human mind has included conation. Unfortunately though, conation hasn't garnered nearly the level of scientific interest and research that cognition and affect have.