Auditors provide a good example of this bias. One hundred thirty-nine professional auditors were given five different auditing cases to examine. The cases concerned a variety of controversial aspects of accounting. For instance, one covered the recognition of intangibles, one covered revenue recognition, and one concerned capitalization versus expensing of expenditures. The auditors were told the cases were independent of each other.
The auditors were randomly assigned to either work for the company or work for an outside investor who was considering investing in the company in question. The auditors who were told they were working for the company were 31 percent more likely to accept the various dubious accounting moves than those who were told they worked for the outside investor. So much for an impartial outsider—and this was in the post-Enron age!
Excerpt from: The Little Book of Behavioral Investing: How not to be your own worst enemy by James Montier