radiation coming from sources other than those being observed
a person's social heritage: previous experience or training
information that is essential to understanding a situation or problem
extraneous signals that can be confused with the phenomenon to be observed or measured
relatively unimportant or inconspicuous accompanying situation
the state of the environment in which a situation exists
energy that is radiated or transmitted in the form of rays or waves or particles
the act of spreading outward from a central source
the spread of a group of organisms into new habitats
