Adults who are anxious about math have more difficulty doing even basic operations, such as counting six squares on a computer screen, than people who do not dread calculating a tip or the amount they owe the babysitter.

This suggests that "mathematics anxiety," in which people get stressed, worried or upset about doing math, may stem from a basic numerical-processing deficit, says Erin Maloney, a researcher in the department of psychology at the University of Waterloo and lead author of a study published in the journal Cognition this month.

It is possible that when the people were children, this deficit made it harder for them to do increasingly complex mathematics in school. But it could be that the anxiety over math came first, and led to the lack of proficiency, says her colleague, Jonathan Fugelsang. "It is a chicken and egg question. It is hard to know what came first," Dr. Fugelsang says.

The researchers are now planning experiments to see if they can reduce or eliminate math anxiety with specialized training. They are considering exercises to improve working memory - the ability to mentally hold and use information and to manipulate or work with facts stored in short-term memory. Working memory is needed for mental arithmetic.

The work is with adults, but it could lead to ways to help children who get stressed out by math. "Is it something that can be fixed? We would like to think so," Dr. Fugelsang says.

Ms. Maloney, a doctoral student, co-wrote the paper with Dr. Fugelsang, Evan Risko at the University of British Columbia and Daniel Ansari at the University of Western Ontario.

Math anxiety can be assessed with a short questionnaire, and 26 per cent of 2,000 students at the University of Waterloo who were screened for the study met the criteria. All had enrolled in a psychology course, but some were studying science or engineering.

One student described getting sweaty palms and breathing too fast every time she took a math test.

Ms. Maloney says she was drawn to this area of research because she, too, gets anxious about math. She says she has found herself staring at a handful of change, unable to calculate quickly whether she had enough to make a purchase. "I tend to be over-prepared. If something is going to cost $3, I make sure I have $10."

Previous research has shown that adults who suffer from math anxiety have problems with more complex operations such as addition that involves carrying, but not with simple addition or multiplication.

This is the first study to show that they are significantly slower at something as basic as counting the number of squares on a computer screen.

In the experiment, volunteers were shown one to nine black squares on a computer screen at a time and asked to say how many there were. Those who were highly anxious about math were slower and less accurate when they counted five or more squares. Adults who weren't anxious about math were faster and better at counting.

Most people can tell if there are one to four squares on a screen without counting, Ms. Maloney says, but after that, they need to count.

More complex math builds on these basic skills, Dr. Fugelsang says. "Slower processing can have much larger consequences with more complex problems," he says.

Ms. Maloney jokes that she is compensating for her math anxiety with her choice of romantic partner. "My fiancé is a mathematician."