The Commonwealth stipulated that he was an expert in his field. The brain is constantly working at interpreting the environment. Through perception, the brain tries to reach a conclusion concerning the environment in order for the person to react to it. However, when the brain receives ambiguous stimuli, it is often difficult or impossible to reach a conclusion about the surrounding environment. The brain will come to a conclusion concerning the environment but the conclusion may be wrong.
Internal factors influence the interpretation of the sense impressions as they come in.
The internal factors are previous experiences, expectations, fears, and anticipations. Every individual's perception is subject to differences based upon the stimuli one receives and what one's internal factors are. In other words, two people with the same vision but different internal factors can, if the stimuli are ambiguous, look at the exact same thing, but reach completely different conclusions about what it is they see. When the stimulus world is ambiguous, that is when the environment is difficult to interpret, humans have a tendency to let internal factors lead them to conclusions about their environment. The more ambiguous the stimuli, the more that internal factors influence the conclusion.