However, it may be wrong to base effectiveness only on recall; we may miss out on those who are 'positively affected' yet do not remember seeing the advertisement. Brain science research suggests that emotions (not feelings) - simple, unconscious and non-verbal responses - help people to make quick decisions in busy markets.
This means that much of what people learn about brands is done so 'implicitly' (with little awareness). For example, if a Coca-Cola advertisement sends the same brand message as before, it may bypass the conscious mind.
If the information is new, however, the consumer may retain it in their working memory. So although effectiveness of advertising can be achieved by measuring recall, it should not be the only method.
Looking for the emotional unconscious in advertising
International Journal of Market Research, Vol 48 Issue 5, 2006