Narrator: Now listen to part of a lecture on this topic in a psychology class.
Professor: Okay, the first kind of memory, we are all very familiar with this, right?
You probably remember what you had for dinner last night.
You have a conscious memory of last night's dinner.
So if I ask you,
"What did you eat last night?"
You could tell me.
But these other kind of memories,
they work differently.
Let's take an example from the world of advertising.
When you're driving along a highway,
you see plenty of billboards, you know, roadside advertisements.
You certainly don't remember them all,
but they still affect you.
Marketing researchers have shown,
but well, to be specific,
let's say there's a billboard on the highway advertising a car called the Panther.
The ad shows a big picture of the car, and above the car in huge letters is the name of the car "Panther".
A lot of people drive by the billboard.
But ask those drivers later if they saw any advertisements for cars,
they'll think about it,
and a lot of them will say "no".
They honestly don't remember seeing any.
They have no conscious memory of the "Panther" billboard.
So you ask these same people a different question.
You ask them to name an animal,
starting with the letter P.
What do you think they'll answer?
Do they say "pig"?
Pig is the most common animal that starts with the letter P,
but they don't say "pig".
They say "panther".
The billboard had an effect,
even though the drivers don't remember ever seeing it.