Yes. Naturalism entails we are fallible and always to some degree in ignorance, therefore we must constantly be vigilant against our own errors and unwarranted presumptions. In fact, according to naturalism, progress in knowledge, and any knowledge of the truth whatever, is only achieved by detecting and correcting or abandoning error. Therefore, if we are not constantly testing our every belief for possible error, at least to the extent that we are able (and the principles of pragmatic economy entail we test important beliefs first and unimportant beliefs last), then we cannot claim to know our beliefs are true, and we can never make any progress in our understanding of ourselves and the world.
Objectivity and bias are tested by the method of falsification, a fundamental component of the scientific method: we ask what would prove us wrong (what would we observe, what would be the case, if we were wrong), and then diligently look for it, using every control we know to avoid our tainting the results of our observations. We then subject our findings, and their basis, to rational and informed peers, to see if they get the same results, or different ones. And we proceed from there until there is agreement among all people who follow reliable methods, and if after all that no agreement results, we hold our belief in reservation, as not yet proved.