If a person (a) is poorly, (b) receives treatment intended... If a person (a) is poorly, (b) receives treatment intended to make him better,
and (c) gets better, then no power of reasoning known to medical science can
convince him that it may not have been the treatment that restored his health.
-- Sir Peter Medawar,...
If I kiss you, that is an psychological interaction... If I kiss you, that is an psychological interaction.
On the other hand, if I hit you over the head with a brick,
that is also a psychological interaction.
The difference is that one is friendly and the other is not