This general term refers to factors within a given organism rather than those external to that organism. Compare with Exogenous.
This general term refers to factors external to a given organism rather than those within that organism. Compare with Endogenous.
Random, undirected movement. Compare with Taxis.
Movement whose direction is determined in relation to a stimulus. Compare with Kinesis.
An environmental agent (such as light or temperature) that entrains an individual's behavior to that environment. Zeitgeber is German for "time-giver."