The questions seemed innocuous. One group of female students was asked about their telephone service, while another group was asked their views on co-ed housing.

Both groups were then asked how pleasant it would be to listen to music for a class assignment, to analyze a poem, to solve an equation or to take a calculus exam -- questions that tested their preference for math or the arts. Students were assigned to the groups at random, so you would expect similar answers from both groups, right?

Wrong.

As tens of thousands of high school, college and university students receive grades for their work in the fall semester this week, there might be more to the grades than whether the students spent the semester partying or studying. A number of experiments show that subtle cues can alter academic preferences -- and test performance -- without anyone being aware of it.

The women in the group who were asked about co-ed housing expressed a greater preference for the arts compared with the women who were asked questions about their telephone service. Researchers believe that reminding the students about their sex -- as a question about co-ed housing would do -- subtly activated an association with the sexual stereotype that the arts are feminine, and math is masculine.

Before we go any further into these troubling waters, let us halt for an important caveat: This phenomenon does not explain all differences in test scores or academic preferences. People clearly do have different temperaments, and talent and application matter greatly. If you spent the last semester tuned out, that provides a simpler explanation for poor grades than the activation of subtle stereotypes.

But the research does raise troubling questions for academicians and parents, not least because the cues we are talking about are so commonplace. Indeed, the research study on the arts-math preferences, conducted by psychologists Jennifer Steele at York University in Toronto and Nalini Ambady of Tufts University in Boston, proved that cues do not have to involve explicit questions.

In another part of the study they recently published in the Journal of Experimental Social Psychology, two groups were told to focus on a plus sign on a computer screen. Periodically, they would see flashes on the right or left.

What the students did not know is that the flashes displayed a word for less than one-tenth of a second, followed by a string of "X's." The word was presented too quickly for the undergraduate women volunteers to be aware of what it said -- but it was enough to make a difference at a subliminal level.

When words with feminine associations such as "doll" or "lipstick" or "skirt" were flashed, students were more likely to express a preference for the arts over math compared with those who were flashed the words "hammer," "suit" or "cigar."

"It is disturbing to think I can show you words outside your awareness and that can influence your preference," Steele said.

Women are not the only ones affected in this way, of course. Reminding white men of the stereotype that Asians are better at math can lower the performance of the white men in math tests.

Again, no one is saying such cues turn brilliant students into dullards, but the cues do cause measurable differences in scores. "Sometimes it is a couple of questions, but when you are talking of acceptance into top universities, one or two questions can make a huge difference," Steele said.

Ambady is currently studying how to address these issues, which obviously have implications for fairness. It gets very complicated: When 5- to 7-year-old and 11- to 13-year-old Asian girls are subtly reminded of their Asian identity, they do better at math tests; when subtly reminded about their sex, they do worse. In other words, both positive and negative stereotypes have effects, and both can be activated simultaneously-- meaning that people seeking to fight stereotypes are well-advised to be cautious.

Ambady said that drawing attention to the girls' individuality -- by asking about their favorite book or movie, for example, or asking them to list a few things about themselves that they liked and disliked -- caused them to do much better on math tests compared with girls primed with a negative gender stereotype that subtly reminded the girls of their group identity.

In another intriguing study, David Butz, a psychology graduate student at Florida State University, found that displaying the American flag in a room when students are asked to solve math problems or anagrams can influence performance. As with other experiments, the students themselves were not aware that the subtle cue made a difference -- in fact, most said they did not even notice the flag.

Butz designed the study after Florida law mandated that an American flag be hung in public classrooms. He found that the flag boosted the performance of white students but not minorities. White students given a math test in a room without a flag solved 44 percent of the problems. Those shown the flag solved 51 percent. Minorities solved 42 percent of the problems without the flag and 41 percent with it -- no difference.

Makes you wonder, doesn't it, about the hidden power that lies in the ordinary things around you?