postdoctoral researchers sheldon and leonard do not appear to be postdoctoral fellows as they do not seem to be awaiting another position nor is their research supervised dr eric gablehauser is their boss not an advisor as postdocs they may have been able to teach the research seminar once so this is not conclusive particularly sheldon is a double ph d holder and child prodigy who was a visiting professor at so he would not be in such an appointment for the most part they do not appear as postdocs there is ambiguity to their positions but they have only been shown having research responsibilities so they may be research professors besides sheldon wouldn't waste his time teaching labberdoodles