The nursing home where I volunteered last year had an interesting sign in the foyer. Like a poster from kindergarten, it displayed the day of the week, the date and the weather. But it had something I’d never seen on a school poster — “The year is: 2004.”

It’s easy to tell that our thoughts are affected by what day of the week we think it is, by how we think we look at the moment, where we think we are and so on. We’d be having different thoughts if we were at Golden Gate Park on Sunday morning.

But these changeable circumstances are only a few of the things that affect us. People have different thoughts when they think it’s still the ‘30s or ‘40s, as I observed at the nursing home, but most of us aren’t aware of the impact of, say, thinking it’s 2005, since we rarely try thinking otherwise.

I think we ought to. It can be informative to try to live for a while with different assumptions.

If the brain includes a massive version of the nursing home’s sign, with slots for keeping track of everything that might influence our thoughts, it’s worthwhile — not to mention entertaining — to change up the answers every now and then to see how much these background facts and assumptions affect us. Think about your personal nursing home “sign” — where you think you are, what sort of world you live in and how you relate to it. Then see if you have different attitudes when you do the following for a few minutes, hours or days:

• Imagine that Stanford is a second-tier university. You don’t get any credit for being here. If you’re a student, you’ll have to stand out here

in order to go anywhere in the future.

• Imagine that no one pays to attend Stanford. Everyone is here on a merit scholarship funded by the endowment.

• Take down the “Stanford” and “Califrornia” and “United States” placards from your sign and put up something else in the slots for where you’re living. Looking around, it’s not hard to imagine that we’re in Melbourne, San Miguel or even a Martian colony. (This one is particularly fun.)

• Switch the terms “men” and “women” and imagine that women are always more intelligent and capable than men.

• Record the “facts” that women provide the bulk of family income, take the leading role in relationships and propose the majority of marriages.

• Consider the humanities more challenging than technical subjects.

• Imagine that you will be executed if you fail to achieve a 4.0 grade point average. Alternately, imagine that no one but you will see your grades.

• Imagine that you are one of the smartest ten people at Stanford. Then imagine that you’re less intelligent than average.

• Think of yourself as incredibly attractive or exceptionally ugly.

• Try believing in God if you don’t, and try disbelieving if you do. Pretend that our culture worships the sun or that the South Bay’s Mission Peak is a holy site.

• Imagine that all living things are sentient and occasionally can communicate with humans. Pretend that plants can understand you if you talk to them.

• Mix up your idea of the state of the world. Tell yourself that the human population is two billion and stable and that there are vast continents we leave relatively unsoiled. Imagine that humans are living sustainably.

• Pretend that humans are only one of many species of similar intelligence and influence on the world. Perhaps North America belongs to the humans, but a race of land-dwelling dolphins rules Asia and gorillas and chimpanzees control Subsaharan Africa.

• Pretend that the world is set to end in 100 years, after you’re dead — but perhaps while your grandchildren are alive.

• Imagine that you’re orphaned or childless.

• Assume that everyone knows everyone at Stanford, or that we’re a single extended family.

• Suppose that you’re at a different point in your life history. If you’re still young, imagine that you’ve already lived out the bulk of your life expectancy. Alternatively, imagine that people are immortal.

• Think of how you’d feel if you could have any job or position you liked. You’re guaranteed admission to whatever graduate school you like, and you can be a professor of any subject at any school. Or, you’re guaranteed success (and a living) as a writer, artist, actor — anything.

• Your priorities are probably on your board. Take them down and put them up again in a different order. Try relationships before work, health before school, or morality before success.

The people I met at the nursing home certainly had different priorities. I’m not sure whether it was because they’d accumulated wisdom, couldn’t remember much or were near death, but they seemed to value their families much more than their accomplishments. They and many other people I’ve met in other countries and other circumstances had immensely different back-of-the mind assumptions and thus very different ways of life.

We rarely notice how much we’re affected by the relatively constant parts of our “reality.” I think we also forget that much of what we consider “reality” is actually subjective. Given how much our assumptions affect us, it seems like a good idea to choose carefully in whatever parts of our reality we actually can choose.

Andrea Runyan is a junior math and computational science major. Please e-mail her at arunyan@stanford.edu with comments, complaints and observations.