Optimissm, Pessimism, and Mental Representations

Fish, perception

How might this cartoon relate to our mental representation or perception of the world? Do we usually perceive situations as positive or negative? Why? Is this genetic? Environmental?

In the above cartoon, it looks like the fish are having two very different experiences which changes their perception of the world. Their environment and how they are interacting with it (or situated in it) changes their feelings and perceptions of the situation.

What might be a more realistic example of this?