There are ways in which you can make that distinction objective to a certain degree. For example, by looking at responses that could be generated in the brain to exactly the same stimulus and there could be differences there.

We can be more or less conscious when you create grades of focus on a subject that is flowing in our stream of consciousness.

There's that effect that is very physical, very down there at the synaptic level, which really means microscopic cellular level, but also molecular level, because all of those structures are operating on an electrochemical basis and so the changes there are very important.

You're not the same after, say, an incredible love affair that went very well or a love affair that went bad. Or something that happens to your health, or something that happened to somebody else's health, that is close to you. Or something that happens professionally.

But whether we want to do it because we want to have people to have a different idea of who we are or not, we do it naturally. So the way we construct our narrative is different from the way we constructed it a year ago. The difference is maybe very small or it may be huge.

When you experience the emotion of sadness, there will be changes in facial expression, and your body will be closed in, withdrawn. There are also changes in your heart, your guts: they slow down. And there are hormonal changes.

The mechanism of primary emotions does not describe the full range of emotional behaviors. They are, to be sure, the basic mechanism. However, I believe that in terms of an individual's development they are followed by mechanisms of secondary emotions, which occur once we begin experiencing feelings and forming systematic connections between categories of objects and situations, on the one hand, and primary emotions, on the other.