Bilateral stimulation is used in EMDR therapy and in some Occupational therapy. I am going to leave some sites if you'd like more information. My "mom" definition is that it is an activity that stimulates both sides of the brain helping to calm the brain.
http://www.emdrinaction.com/store/equipment -the above equipment plus some info
http://nejm.highwire.org/cgi/content/abstract/349/20/1925 - the abstract of a study on bilateral stimulation
http://www.emotionaltuning.com/gpage6.html - What is bilateral stimulation
http://www.focusstones.com/barbara-walters-applies-bilateral-stimulation.html -Barbara Walters and bilateral stimulation