1. There is some sort of a motive that arouses or sustains the activity. This motive may appear in the form of need, a problem or a goal. Essentially the equilibrium of the organism is disturbed and this impels the organism to react to the situation in an effort that comes to terms with it.
2. Several different kinds of responses are made.
3. Finally there is a progressive integration and establishment of the reaction by which the goal is achieved.
4. There is progressive elimination of superfluous unsuccessful or wrong form of activity.
The essential point in trial and error is the second point-the process by which the correct response is identified through trying various responses until a solution which permits the attainment of goal is achieved.