There were more than a few hair-pulling screams at the TV screen during LOST's run. Many commentators threw in the towel when none of the main characters would ask each other important questions. Many commentators spit out their adult beverages when characters would do 180 degree personality turns.
One explanation for these dumb character turns is mass psychology.
Mass psychology isn't a new science. In 1895 a French social psychologist named Gustav LeBon wrote a book called The Crowd: a Study of the Popular Mind. The author basically concludes that people tend to do stupid things when operating as a group.
Well, that is a concise statement of fact.
In LOST, the "group think" was always in play. And many dumb things happened as a result. It was always odd that the group split in half when Jack wanted to move the camp to the safety of the caves (and a fresh water supply). That seemed to be the most logical and sound plan. But the group division was made when most of the survivors preferred to stay on the beach in the hope of rescue. But that same group did nothing to help the cause of rescue (such as a signal fire, an SOS, or building a raft until much later).
One of the strangest group think missions was journey to the radio tower. Why the entire group had to go on a long, dangerous jungle trek to a malfunctioning radio tower made no sense. In the past, a few survivors would trek into the jungle on a mission to find dynamite, a kidnapped person like Walt or Claire, or to hunt for food. But having the entire camp march up the mountain to see the tower and listen to a signal wasted time and resources. The dumbness was revealed when after reaching the group goal, the entire group then turned around and marched back down to the beach.
Then there were the oddest group decision. When Jack's gang is rescued by Penny's boat, he made the suggestion that they all "lie" about the events in order to "protect" the people left behind. This was dumb for many reasons, the first and foremost was that they all saw the island vanish - - - so there was no evidence there was anyone left alive to protect. Then the group decision to create an elaborate back story of survival to throw rescuers from the island also made no sense since the group had no idea where the island was in the first place. If the O6 really wanted to save their friends, they would have told the authorities the truth and led their own mercenary force to liberate the island.
Another strange decision was the group cult status of the Others. They followed Ben, but did not trust him. They worshipped Jacob, but Jacob really did not care about them. They lived like gypsies in the wild while their leaders took over the Barracks. Alpert said that the Others had a different mission than Ben's, especially on the pregnant women dying issue. So why did the Others remain loyal to an outsider like Ben? Out of fear, tradition or just dumb group think?
One explanation of the dumb group think is that all of the people coming to the island have some traumatic events in their lives, including surviving shipwrecks, plane crashes and kidnapping. It is also possible that the "infection" affects the mind to numb the primal instincts and curiosity as a means of controlling people on the island. Likewise, the unique electromagnetic energy source could affect mental abilities. Or it could be sloppy writing and a lack of continuity.
Whatever the cause, there was a mass psychology event playing out in the series. Whether the final phase of this was the characters "creating" a false after life in the sideways world is unclear.