The phenomenon which makes our thoughts repeatedly turn to one and the same subject is term a “dominant”. It’s a complicated psycho-physiological process, but to put it simply, for various reasons, a site of increased excitability develops in the brain which, apparently, attracts all the impulses of excitability from the rest of the brain sections and thus intensifies its own activity.
Everybody has more than once experienced the action of a dominant. When one is engaged in interesting and important work, such as preparing for an examination or rehearsing a part for a new theater performance, it is quite often difficult, or even impossible, to switch over to something else. This is an important feature of the brain activity that allows us to concentrate our resources on the task which has to be given priority at a particular period in life.
There are many reasons why a person may be overcome by a dominant. It may be due to lofty patriotic feelings, a burning interest in one’s work, love for one’s sweetheart, or a maternal instinct. Producing a dominant state, these emotions enable people to use their gifts to the full, to surmount every difficulty and obstacle. Love for the people, evoking the corresponding dominant, helped the Russian revolutionaries not to give up hope in the prisons and hard labor colonies and at first opportunity to resume the struggle against tsarism. A similar dominant state helps soldiers in combat to suppress their fear, staunchly endure cold, heat, thirst and hunger, wrestle with fatigue and to put all their efforts into defending their country.
But a dominant state is not always useful. If the reason for the dominant is insignificant, and yet it occupies the entire activity of the brain, it may interfere with more important functions.
A person may often become very biased due to a dominant state. It is sometimes rather boring to hear a young mother talk of nothing else but her baby, even in the theater, a lecture hall, or at a dinner party. On the other hand, she may often draw extremely clever comparisons and parallels with regard to those seen or heard which might never have occurred to you.