periodic attractor

A periodic attractor, also called a limit cycle attractor, is an attractor that consists of a periodic movement back and forth between two or more values. The periodic attractor represents more possibilities for system behavior than does the fixed-point attractor. An example of a period two attractor is the oscillating movement of a metronome or, in psychiatry, a bipolar disorder that causes a person's mood to shift back and forth from elation to depression.