A recent article by Po Bronson and Ashley Merriman, in The New York Times, discusses some of the latest research into stress and how we deal with it. It turns out that there is no universal rule for how people handle stress; individuals react to stress very differently.
In part this reaction is explained by a genetic predisposition based up the variant of a gene know as COMT, which affects the rate at which dopamine is cleared from the brain. Basically, an optimal level of dopamine in the brain helps the pre-fronal cortex, the area of the brain that "plans, makes decisions, anticipates future consequences and resolves conflicts." Those with one version of the gene are much better able to use the pre-frontal cortex to performs its functions in stressful situations such as standardized testing. However, those with the other variant of the gene can suffer from a relatively disorganized, slow-to-respond pre-frontal cortex, which may not perform as well in stressful situations.
Please note however, that those with this "disadvantage" may actually have an advantage in other situations that are not characterized by high stress. So there really is no specific optimal genetic make-up in this case. It all depends on the situation one is in.
One important finding of these research studies is that practice and familiarization with the stressful situation (for example, the SAT exam), can help reduce stress and minimize the negative consequences associated with it for those who do not tend to react as well to stress. In other words, preparing and rehearsing for the stressful situation can make it much less stressful. So if you or your child falls into this category, preparation is crucial.
Another important take-way message from this research is that not all stress is bad. In fact, some stress can actually be very helpful for people, especially for those who tend to perform better in stressful situations.
Ultimately, students need to learn to recognize their own strengths, weaknesses, and the characteristics of their own learning and cognition in order to harness the power of their strengths and to work around their weaknesses (in this case by adequately preparing for the stressful situation). Self-knowledge is the key.