EMDR therapy was developed from clinical experimentation and experience. Although a comprehensive approach, the dual attention stimulus (DAS; also sometimes called "Bi-lateral stimulus") is a key technique used during the desensitization and reprocessing phases of treatment. Research consistently shows that EMDR therapy with DAS is more effective than EMDR therapy without DAS. DAS usually takes the form of bilateral eye movements (via hand movements or a light bar), tapping, vibrations (via “buzzers”), or tones (via headphones). A recent study shows that eye movements may have a slight edge over other DAS forms in terms of potency, but all forms are effective. What matters most is matching the form to what works best for the client.