The question of when to use effect and when, affect, came up today. Since I have already dealt with this confusion in a past Good Word (see effect by clicking here), I won’t rehash it here. However, it reminded me of another distinction that often goes unnoticed.
Over the last half of my 35-year teaching stint at Bucknell, the question of my influence over the thinking of students periodically emerged. It became a rather vital question in the 60s and 70s and led to my thinking through the issue.
By the end of the 70s I was telling my students that my intention was not to influence them but to affect them. I was being paid to have some impact on their thoughts and abilities but I tried to avoid conveying my prejudices to them. (Indeed, I try to avoid prejudices in the first place.)
It seems to me that the verb influence implies prejudice in a way affect does not. To affect the thinking of someone, you either have a good or bad effect on it but you do not (necessarily) prejudice it. To influence an election is to tilt it one way or ther other; to affect it is to improve or undermine the process itself, not skewing it in any direction.
The distinction here is subtle and often overlooked but it is a good distinction for careful speakers and writers to work with.