Dual attention stimulus (DAS): a simple definition

A dual attention stimulus (DAS) is the external cue, like eye movements, alternating tones, or taps, that EMDR uses during reprocessing. It occupies part of your attention so the rest can stay anchored in the present while a memory is held in mind. Eye movements are the most common form, but any alternating left-right input works the same way.

What forms does a dual attention stimulus take?

The EMDR Institute, founded by Francine Shapiro, lists three forms: eye movements, following a therapist’s hand, a light bar, or a moving target; auditory tones alternating between ears through headphones; and taps or tactile pulses alternating hand to hand. EMDRIA’s glossary describes the shared method as engaging a client in bilateral stimulation through one of these channels while they concentrate on a target memory, which is thought to activate the brain’s own information-processing system. Eye movements are the original form Shapiro described in her foundational text, EMDR Therapy: Basic Principles, Protocols, and Procedures (Guilford Press, 3rd ed., 2018), and still the most commonly used. Tones and taps exist as practical alternatives, useful for telehealth sessions, eye strain, or anyone who finds tracking a moving target harder to sustain.

Is a DAS the same as bilateral stimulation or dual awareness?

Close, but the terms point at different pieces. Bilateral stimulation (BLS) is the general term for the alternating left-right input itself. Dual attention stimulus is the same thing, named for its purpose: giving one part of your attention something to track so the rest can stay with the memory. Dual awareness is different again. It’s the internal state a DAS is meant to support, holding a memory and present-day safety in mind at once, rather than the stimulus doing the supporting.

Why does EMDR use an external stimulus at all?

The leading explanation involves working memory. Recalling a memory and tracking an alternating stimulus appear to compete for the same limited mental resources. A 2022 review in BMC Psychology found this kind of dual-task condition reduced how vivid and emotional recalled memories felt, compared with simply recalling them without a competing task. Researchers haven’t settled on one exact mechanism, and other explanations, like an orienting response to the movement itself, are still debated alongside it. What’s consistent across EMDR’s eight phases is that a DAS runs throughout the active middle phases of treatment, not only at the very start.

Can you use a dual attention stimulus on your own?

Yes, for everyday stress and lighter material. A screen-based moving target works as a visual DAS; alternating tones through headphones work as an auditory one, the same principle behind clinic tools like an EMDR light bar or handheld buzzers. EmEase, a self-guided EMDR app, offers both visual and audio bilateral stimulation for everyday stress at app.emease.com. It’s built for a stressful moment or a looping thought, which is roughly where self-guided EMDR draws its limits. A therapist controlling the stimulus in the room is still what heavier or older memories call for.