Now listen to part of a lecture on this topic in a psychology class.
Consider this experiment.
Two groups of people were asked to watch TV.
And while they were watching, a picture flashed on the screen, less than a second, very quickly so it was barely noticeable.
The picture was a boy with a birthday cake.
Now like I said, there were two groups, and each group saw a slightly different version of the picture.
One group got the boy looking angry.
In fact he was actually throwing the cake on the floor.
The other group got a picture of the boy smiling, happy, holding out the cake like he was offering it.
Same boy, same cake, but different emotions expressed in each picture.
Everyone was then asked to look at a different image.
Now this is a third image, right?
Again it's the boy and the cake, but this time the image stayed on the screen.
In this picture, the boy is just holding the cake, basically no emotion on his face, everything very neutral.
Now remember, nobody knew they'd already seen a picture of this boy.
After a minute, everyone was asked to describe the boy's personality.
Those who'd been exposed to the image of the angry boy, they generally described the boy's personality negatively.
Those who'd earlier seen the happy boy described him, well, positively.