Knowing the Latin sources of these two words should indeed help anyone who might want to use them. If you would both use and teach the verb 'to effect', why? The point of teaching is to improve students' usage, in meaning, skills, and grammatico-lexically, without having them waste too much energy on rare usages, inaccuracies, or inapplicable practices. Unless the student is writing or reading psychological works, I do not see how this usage would be helpful, so I would teach it only using discretion. On the other hand, the noun 'affect' I would use in connection with the idea of 'affection' or emotion. So because I have not used and would not use it, I would not teach it. As a graduate student I cannot recall using effect as a verb, and in my readings I never saw it make a point clearer. My answer, though I'd rarely go this far on this rabbit trail, is that I rarely see 'to effect' except in connection with 'to effect change', for which I would greatly prefer to use 'cause' or 'change'. To get into questions of what is possible and in which contexts, finally progressing to when should someone use 'effect' as a verb or 'affect' as a noun, is likely to be a wasted exercise both for myself and for the student. Lucy, it appears to me, is confused about the basic difference.

Which is correct: the dictionary definitions (and if so, which dictionary), academic usage, or common usage?

Affect me