This is pretty fascinating. If you think you are competing against a smaller number of people, you perform better - or at least faster - than if you perceive the field to be large.
Participants were told they were competing against either 10 or 100 other participants and that those scoring in the top 20 percent in completion time would receive $5. The short quiz contained four general knowledge multiple-choice questions (e.g. "Who is the Secretary General of the UN?") and four true-false statements (e.g., "Michigan is shaped like a shoe").Those that were told they were in the group of 10 performed on average 10% faster (29 secs vs. 33 secs) than those told they were in the group of 100. Did that make them less accurate? Not sure. Is it the specifics of this experiment? Or is there really something to this idea that if you think you are competing against a smaller field, you will try harder - even if your goal is percentile placement (so it shouldn't matter how many people you are against)?
Once the first experimenter gave participants the packets and instructions, the second experimenter, blind to the experimental condition, informed participants he would begin timing them with a stopwatch.