BILATERAL STIMULATION · 15
Bilateral stimulation, the active dual-attention element of EMDR.
A clinician-facing reference to bilateral stimulation — what it is, how it works, and how the modalities compare in the room and online.
DEFINITION
Bilateral stimulation (BLS) is the rhythmic, alternating left-right sensory input used during Eye Movement Desensitization and Reprocessing (EMDR) therapy. It can be visual, auditory or tactile, and it functions as the dual-attention component of the standard eight-phase protocol.
What is bilateral stimulation?
BLS is one of the defining procedural elements of EMDR. It is delivered while the client holds a target memory in mind, and it is used across all eight phases of the standard protocol — most intensely in Phase 4 (Desensitisation).
How does bilateral stimulation work?
The dominant contemporary explanation is working-memory theory: dual attention taxes working memory during recall, reducing the vividness and emotionality of the recalled image. Other proposed mechanisms include an orienting response, interhemispheric communication and REM-like reconsolidation.
Modalities: visual, auditory, tactile
Visual BLS uses eye movements tracking a target. Auditory BLS alternates tones between the left and right ear. Tactile BLS uses alternating taps or vibrations. Studies have not consistently shown one modality outperforms another.
Bilateral stimulation online
Visual and auditory BLS can be delivered remotely through a browser. Sub-100 ms sync keeps therapist adjustments essentially instantaneous on the client screen, preserving the fine timing EMDR requires.
Frequently asked questions
What is bilateral stimulation?＋
Bilateral stimulation (BLS) is rhythmic, alternating left-right sensory input used during EMDR therapy. It can be visual (a moving target), auditory (alternating stereo tones) or tactile (alternating taps or vibrations).
How does bilateral stimulation work?＋
The leading account is working-memory theory: performing an attention-demanding dual task while recalling a distressing memory taxes working memory and reduces the vividness and emotionality of that memory. Additional proposed mechanisms include an orienting response and REM-like memory reconsolidation.
Is one modality of BLS better than another?＋
Studies comparing visual, auditory and tactile BLS have not consistently shown superiority of any single modality. Clinical guidelines recommend choosing based on client preference, comfort and situation.
Can bilateral stimulation be performed remotely?＋
Yes. Visual and auditory BLS can be delivered through a browser tab on the client's screen. BilateralSync synchronises the client display to the therapist's controls with sub-100 ms latency.
How fast should bilateral stimulation be?＋
Standard EMDR protocols recommend faster sets (around one left-right cycle per second, or slightly faster) during desensitisation and slower sets during resource installation. Speed is titrated based on the client's response.
Related reading
Bilateral Stimulation
What is Bilateral Stimulation?
Bilateral stimulation (BLS) is alternating left–right sensory input used in EMDR therapy. Learn what it is, how it works and how clinicians use it.
Theory & Research
How Bilateral Stimulation Works
How does bilateral stimulation work in EMDR? A clear overview of working-memory theory, orienting response and current evidence for the mechanism of BLS.
Bilateral Stimulation
Visual Bilateral Stimulation
Visual bilateral stimulation is the classical BLS modality in EMDR — a moving target the client tracks with their eyes. Learn how it is used and configured.
Bilateral Stimulation
Auditory Bilateral Stimulation
Auditory bilateral stimulation uses tones alternating between the left and right ear. Learn how stereo BLS is used in EMDR and how to configure it online.
Bilateral Stimulation
Tactile Bilateral Stimulation
Tactile bilateral stimulation delivers alternating physical sensations — taps, buzzers or self-tapping — during EMDR reprocessing.
Theory & Research
Working Memory Theory of EMDR
The working-memory theory is the leading contemporary explanation for how bilateral stimulation contributes to memory reprocessing in EMDR.