Senior investigators received their degrees more than five years ago and have since been active in their fields. Junior investigators are:
- graduate students;
- researchers who have earned their degrees within the past five years; or
- those who have previously earned degrees in other fields and entered their present field within the past five years.
In the case of multi-author papers, the category is determined by the status of the first author listed, unless another author is designated at the time of submission as the primary investigator, in which case the latter will also be the award recipient. Authors need not be members of Mensa.