Those two are some questions i have in mind, analyzing the psychology thats portrayed in chapter 1-10.
How do other people’s/groups of people’s actions worsen the situation? How bad do things have to get before people feel they have no option but to leave?
In The Grapes of Wrath the sharecroppers have lost or are about to lose their means of making a living. They leave when they realize that they don't have any choice anymore, because the choice was made for them--many of them were forced off their land.
Throughout his novel John Steinbeck's concept of the "oversoul" is prevalent; people also are caught in something larger than themselves. This largeness is symbolized by the "monsters" of Chapter 5, the diesel tractors that do not run on the ground, but on their own roadbeds. Steinbeck describes how man cannot control the monster that does not allow him to see the land as the dust is stirred up, dust that itself is introduced in Chapter 1 as an unstoppable force against the Okies, as well.
The "monster" is a force that dehumanizes:
The tenant pondered. Funny thing how it is. If a man owns a little property, that property is him, it's part of him, and it's like him. If he own property only so he can walk on it and handle it and be said when it isn't doing well, and feel fine when the rain falls on it, that property is him, and some way he's bigger because he own it. Even if he isn't succesful he's big with his property. That is so.
But let a man get property he doesn't see, or can't take time to get his fingers in, or can't be there to walk on it--why then the property is the man. He can't do what he wants, he can't think what he wants. The property is the man, stronger than he is. And he is small, not big. Only his possession are big--and he's the servant of his property. That is so, too.
The farms of California were not like those of the Midwest, which were owned by individual farmers who worked the land themselves. Instead, in California wealthy people in the Northeast owned these farms and they were dealt with by banks as a big business. Rarely did the owners visit these farms; rather, the owners hired managers to take care of the hiring of workers, etc.
How are other people's or groups of people's actions worsening the situation? Two easy examples. First, how about the guy who takes the job driving the bulldozer. He's one of them, but in these times he has to make a living. In doing so, in ensuring he has his sandwich to eat for lunch every day and can feed his family, he is helping displace his former neighbors and friends. Second, I'm thinking of all the people who are taking advantage of desperate people and are buying their household goods for a song and then gouging them on the purchase of a vehicle with which to travel west. This is way less forgivable than just trying to feed a family; however, even the small things contribute to the bigger picture of displacement.
I would pay attention to how the role of economics and wealth influences the interactions between people. Steinbeck demonstrates a strong tendency to showing how the relationships between groups of people are altered when economics and material conditions are involved. In terms of how psychology is impacted by economics, Steinbeck shows that people in dire economic conditions can have elements of community present, but the fear of economic shortcomings can threaten such notions of harmony. It seems to be a telling message in this particular economic crisis in which we are immersed right now.