Thomas Edison was a rather intelligent guy, but it seems that he had a different way of ascertaining as to whether or not an individual would be worthy of a job after meeting them for an interview. Upon them arriving, Edison was known to provide them with a bowl of soup. He would then pay close attention to see if they added some salt or pepper before tasting it.
This does sound rather basic, but it allowed him to see if they were analytical in their thoughts and also as to whether or not they made some assumptions and just believed that there was insufficient seasoning before they even checked it out. If they did go ahead and use salt or pepper before tasting, then they would never get the job.