May be able to use the has agent = has active participant relationship for defining this. May want to work with OBI to define this term in a more general sense for investigations.

An observing process in which the observing entity consists of one or more humans.

an entomologist recording the presense of butterflies while walking a transect

a biologist recording an observation of an animal in a field notebook

http://purl.obolibrary.org/obo/IAO_0000123