A psychology student was to help a professor in conducting a personality
test. The room was set up with various props in order to move through
the assessment quickly. The first person to enter the room started
through the test.

"How does this glass of water look to you?"
Person 1: It is half empty.
Student writes 'pessimist' in his report.

Person 2 enters the room. "How does this glass of water look to you?"

Person 2: It is half full.
Student writes 'optimist' in his report.

Person 3 enters the room. "How does this glass of water look to you?"