With respect to the location of Cumorah, members of the Church have one of two biases:
(i) They are biased in favor of believing the prophets (who have consistently taught that Cumorah is in New York)
(ii) They are biased in favor of believing the M2C intellectuals (who have consistently taught that the prophets are wrong because Cumorah is in southern Mexico).
[Note: there are a few proponents of other non-New York locations, but the principle is the same. Either you follow the prophets or you follow the intellectuals.]
Does it matter which bias one has?
It might seem self-evident that a bias against believing the prophets is undesirable, at least for active members of the Church. It seems especially problematic to have BYU/CES employees teaching students to disbelieve the prophets.
These teachers use euphemisms for disbelieving the prophets, such as "The New York Cumorah was only their opinion, and they were wrong," or "They spoke to the best of their understanding at the time, but they were wrong."
That line of reasoning can be used to reject the prophets on whatever topic you want. As we've discussed, M2C is a "gateway drug" toward disbelieving the prophets on other topics.
As pervasive as the M2C bias is, it can be changed. I know, because I once shared that bias, but I changed my bias toward believing the prophets.
For me, there was always a bit of cognitive dissonance with M2C because I had learned when I was young that Cumorah was in New York. I knew it was taught in General Conference, but until the last two years or so, I didn't know about Letter VII and I certainly didn't know it was copied into Joseph's history and republished so many times.
My ignorance left me susceptible to the M2C ideas I learned at BYU as a student, and later as an avid follower of FARMS, BYU Studies, etc. I trusted my professors. I trusted the faithful LDS authors who taught M2C. I've explained before that I reviewed John L. Sorenson's book An Ancient American Setting for the Book of Mormon because I had an archaeologist friend who was doing a peer review.
I've met lots of people who have changed their bias from rejecting the prophets to accepting them, but it seems that in the Church today, far more people follow the intellectuals than follow the prophets regarding the Hill Cumorah. This is understandable given the preference given to M2C material in Church media, art, visitors centers, and, of course, at BYU/CES.
Some people are uncomfortable with my criticism of BYU/CES. Let me put it this way. I'm not critical of any individuals, all of whom are wonderful, good, well-intentioned, etc. What I criticize is the continued teaching that the prophets were wrong, which appears in the fantasy maps taught at BYU and the Institute manual.
So how do we "cure" confirmation bias?
Researchers have shown that knowing confirmation bias exists does not cure it. We also know that more information does not cure confirmation bias because our minds interpret every bit of information so as to confirm our biases (often by dismissing as false, wrong, or illogical any contradictory bits of information--which is how M2C advocates characterize the teachings of the prophets).
I won't take the time to go through a detailed strategy today, but here are some of the ways the M2C bias has been cured in the past.
1. Read Letter VII. Ask yourself, why did Joseph Smith have this copied into his history and have it republished so many times? Why would President Cowdery deceive the Church by claiming it was a fact that the final battles took place west of the Hill Cumorah in New York, and that Mormon's depository was in that same hill? A few months later, the Savior appeared to Joseph and Oliver in the Kirtland temple (D&C 110). Letter VII continued to be taught and published afterward.
2. Read the accounts of Mormon's depository. Ask yourself, why did Brigham Young think this was so important that he spelled it out just two months before he died? Why did he fear it would otherwise be forgotten by members of the Church? And if Brigham Young was correct, this means Joseph and Oliver spoke from personal knowledge when they wrote Letter VII.
3. Consider the number of people you have to disbelieve to maintain your M2C bias. These include Joseph Smith, Oliver Cowdery, David Whitmer, Brigham Young, Heber C. Kimball, Wilford Woodruff, the Pratt brothers, Anthony Ivins, Joseph Fielding Smith, James E. Talmage, LeGrand Richards, Marion G. Romney, Mark E. Petersen, and Gordon B. Hinckley. Do you really believe all of these prophets misled the members of the Church?
4. Consider the scriptural comments about scholars, professors, and the learned.