Professor Chadwick evaluated a graduate student's research proposal negatively simply because he had heard a rumor about the student's incompetence. When later informed that the rumor had been patently false, the professor's assessment of the student's research proposal remained almost as negative as it had been originally. This best illustrates:

Explanation: When people create a belief that is based on something that may be true but also on rumours, they usually stay with that belief even though the opposite is proven and there is clear evidence that the belief is not true. It is simply a psychological tendency in humans, as in Professor Chadwick's case, the perseverance of belief or also known as belief persistence, that is, not giving up the initial belief even in the case of valid newly acquired information that the belief is incorrect.