Although i don't know much about the science behind test taking i am currently enrolled in grade school and i have a moderately strong opinion on the topic. I have been enrolled in the US's gifted (magnet, probe) program since i was 5 years old, however sometimes when i take exams on materials i know 'like the back of my hand' i receive mediocre grades. I absolutely hate taking written exams and so do most of my peers. I fell as it is an inefficient way of testing a student's knowledge. (I dislike standardized testing even more because we are compared by our school, county, state, country, and worldwide average and you never feel competent.) i know that if i engaged in an interview-like conversation with my teacher about the subject they would be very pleased, however our scantrons seem to think otherwise. i also know that some students are rather shy and better spoken on paper, so i think students should have an option of a verbal or written exam for whichever fits them best. for example, I become nervous and fidgety when i take written exams while i stand up straight and loudly project information when i give an oral report. Every child learns their own way, we should be evaluated our own way also.
*I'm assuming that your question was referring to written exams, i hope i was correct.*