The brain has two sides, the left side which control logical and rational thinking, and the right side which is more dominant in artistic activities which require imagination.
What’s more, even when we do activities which are more successful using the right side of brain, we often use the left side instead. An example of this drawing. Many people try to identify the thing they are drawing, e.g. an eye or a nose, and then copy their idea or what an eye or a nose looks like. In other words, they draw what they know and not what they see. This is an example of left brain thinking and the result is usually very childlike.
However, you can switch off the left side of the brain when you are drawing by using the following technique, invented by Betty Edwards, who has written a book about learning to draw the right side of the brain.