Part of the issue of living in this information-centric age, is the default understanding that humans are logical, and given enough explanation, could understand why things need to be done certain ways. This thread exists to demonstrate how woefully illogical, and thus unobjective, humans are.
The Asch Conformity Experiments (1950s) were conducted to see how humans would yield or defy the majority opinion (using very simple questions, simple enough for a toddler to get correct). When the majority were giving the wrong answers, only 63.2% of the test subjects were able to get the answer right. On all tests, only 5% were always swayed by the crowd, but only 25% constantly defied the majority's wrong opinions. Therefore, the rest were swayed by the majority's wrong opinion some of the time. From these experiments, we can see humans distorting reality to fit in with the majority.
Cognitive dissonance is another example of human inobjectivity. Festinger and Carlsmith (1959) conducted an experiment to observe how humans deal with cognitive dissonance. The experiment used a Stanford University student (not some random dummy) to complete a boring task. Once the task was completed, the student was then offered a large sum of money to set the experiment up for someone else, provided the student said that the experiment was interesting. Despite the student initially saying that the task was boring, when the student was offered money to say that it was interesting, he suddenly found explanations as to why it was interesting, and the researchers found that the student was starting to believe the experiment was interesting. Cognitive dissonance distorts reality, based on one's own interest.
The Halo Effect is the idea that a singular positive trait seen in a person will result in other people viewing that person with all their traits as being good. Nisbett & Wilson (1977) found that when two sets of students watched the same lecture, but with the lecturer in different moods. If the students saw the lecturer in a happy mood, they would attribute other positive attributes to the lecturer, and vice-versa. Students stood by these judgements, despite being informed of this bias, and also given opportunities to revoke their judgement. Most people are completely not aware of this Halo Effect, and how irrational they are being when it's in play.
Perhaps the most fascinating conclusion we can draw from human unobjectivity is that ideas of Democracy are lauded, despite most human's inability to vote with any kind of objectivity (and also the myriad of other problems with Democracy: (https://www.debateart.com/forum/topics/136)). It takes surprisingly little for humans to become unobjective, and thus illogical.