The choice between two pleasant things is generally easier than that between two unpleasant unless questions are involved which cut deeply into the life of the individual. Such a conflict situation can upon occasion also lead to an oscillation between two attractions. It is of considerable importance that in these cases a decision between two attractions. It is of considerable importance that in these cases a decision or one goal alters its valence in such a way as to make it weaker than that of the renounced goal.

p. 123. - A Dynamic Theory of Personality, 1935