Edward L. Thorndike, answered from the texts and cited to the page.
Learning is the formation of bonds between situations and responses, selected and fixed by their consequences. That is the whole of it, stated plainly. Watch a chick put into a pen from which it must find its way out. It does not study the arrangement, reason about the exits, or form any plan. It moves, and the movement that brings relief is the one that gets fixed.
Put it back, and the useless movements drop away; the successful one comes sooner. Three chicks of mine learned to traverse a labyrinth of twenty-three successive associations in this fashion, without a single inference, without any evidence that an idea of the maze or the food guided a single step.1 The learning is adequately accounted for as the strengthening and weakening of bonds between a situation present to sense and responses in the nervous system that issue then and there in movement.2
Two laws govern this process. The Law of Exercise: other things being equal, the oftener a given response is connected with a certain situation, the more likely it is to be made to that situation in the future — exercise strengthens the bond, disuse weakens it.3 The Law of Effect: the greater the satisfyingness of the state of affairs that accompanies or follows a response, the more likely that response is to recur; the greater the annoyingness, the less likely.4
Satisfying results stamp in; discomfort stamps out. Human nature does not do something for nothing, and it is the consequences of a response that are the chief engine of change.5 One refinement matters and is easily missed. The bond is not always formed with the gross total situation as a lump. A cat that has learned to escape from a dozen boxes by operating latches will, in a new box, attend more to small manipulable objects than it did before its training; and a cat that has learned to turn a button will operate it just as well whether the box faces North or South, whether it is painted somewhat darker or made somewhat larger.6
The connection is made predominantly with certain elements or features of the situation — what I call the Law of Partial Activity: a part or element of a situation may be prepotent in causing response, and may have responses bound to it regardless of some of its accompaniments.7 The animal does not abstract as a thoughtful man might, but it does something that is the germ of the same process.
That, in sum, is the theory: bonds, formed between situations and responses, strengthened by satisfying consequences and by exercise, weakened by annoyance and disuse, and connected not always with the whole situation but with its prepotent elements. The mind, in animal and man alike, is the sum of such connections.
Three chicks thus learned to go through a sort of long labyrinth without mistakes, the 'learning' representing twenty-three associations.Educational Psychology Vol 2 The Psychology of Learning
The three cases of learning quoted are adequately accounted for as the strengthening and weakening of bonds between a situation present to sense and responses in the nervous system which issue then and there in movement.Educational Psychology Vol 2 The Psychology of Learning
the Law of Exercise, that, other things being equal, the oftener or more emphatically a given response is connected with a certain situation, the more likely it is to be made to that situation in the future.Education A First Book
The Law of Effect is that, other things being equal, the greater the satisfyingness of the state of affairs which accompanies or follows a given response to a certain situation, the more likely that response is to be made to that situation in the future.Education A First Book
Human nature does not do something for nothing. The satisfyingness and annoyingness of the states of affairs...Education A First Book
it makes little or no difference whether the box from which a cat has learned to escape by turning a button, is faced North, South, East or West; and not much difference if it is painted ten per cent blacker or enlarged by a fifth.Educational Psychology Briefer Course
the general Law of Partial Activity — that a part or element or aspect of a situation may be prepotent in causing response, and may have responses bound more or less exclusively to it regardless of some or all of its accompaniments.Educational Psychology Briefer Course