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Explore how EMDR’s bilateral stimulation (eye movements and tapping) helps the brain reprocess trauma. Understand the science behind BLS, eye tracking, and tactile grounding.
When most people first hear about EMDR therapy, they’re intrigued — and often a little skeptical. How could something as simple as eye movements or rhythmic tapping possibly help with trauma?
But beneath the simplicity lies a profound neurological truth. These methods — formally known as Bilateral Stimulation (BLS) — are grounded in how the brain stores memory, and more importantly, how it holds on to unprocessed pain. When trauma isn’t fully integrated, it lingers — not just in the mind, but in the body. It can show up as flashbacks, anxiety, shutdown, or a vague sense that something isn’t quite right.
This article explores the two most commonly used BLS approaches in EMDR: eye movements and tapping. Both help the brain unstick what’s frozen. Both reduce distress. But their effects, delivery, and impact can vary depending on the client — and the context.
What Is Bilateral Stimulation (BLS)?
What Is Bilateral Stimulation (BLS)?
Bilateral Stimulation refers to gentle, rhythmic input that alternates left–right across the body. In EMDR sessions, this is typically done through visual tracking (moving the eyes back and forth), tactile tapping (on the knees or shoulders), or auditory tones. The goal is to stimulate both hemispheres of the brain while the client brings up a memory, belief, or sensation that carries emotional charge.
Think of it as guiding the brain out of “trauma time” — where the past still feels like it’s happening — and back into the present, where integration and relief become possible. As one client once described it: “It’s like my brain finally digested the experience.”
The Neuroscience Behind Eye Movements
The Neuroscience Behind Eye Movements
Eye movements were the original form of BLS developed by Francine Shapiro. Since then, they’ve become the most studied and widely used EMDR technique. Neurologically, they work by taxing working memory while activating visual-spatial networks. This dual action appears to weaken the vividness and intensity of traumatic images — a mechanism supported by neurocognitive research.
They may also replicate aspects of REM sleep, a phase in which the brain naturally consolidates emotional memory. This REM-like stimulation helps explain why clients often experience insight, resolution, and emotional relief after just a few rounds of processing.
Meta-analyses (such as Lee & Cuijpers, 2013) support the effectiveness of eye movements in reducing distress and speeding up reprocessing — particularly for PTSD.
And What About Tapping?
And What About Tapping?
Tactile BLS, such as alternating taps or hand-held buzzers, offers a more grounded, body-based route. It’s often the method of choice for clients who find visual tracking overwhelming, who are working through dissociation, or who attend therapy via telehealth.
Research supports its clinical effectiveness — though it’s been studied less extensively than eye movements. Schubert et al. (2008) found that tapping significantly reduced distress in real-world clients. Maxfield et al. (2008) reported meaningful reprocessing outcomes using tactile stimulation. And Kemp et al. (2010) observed that for clients with complex trauma, tapping could help anchor awareness and prevent dissociation.
While it may work slightly more gradually than eye movements, tapping is often perceived as gentler, more embodied, and easier to tolerate, especially in the early phases of trauma work.
It’s Not About Which Is Better — It’s About What You Need
It’s Not About Which Is Better — It’s About What You Need
The most important question isn’t “Which method is better?” — but rather, “What does your nervous system need to feel safe enough to heal?”
Some clients feel steady and present with eye movements. Others become overwhelmed and need the slow, grounding rhythm of tapping. These aren’t just preferences — they reflect the way different nervous systems respond to sensory input, relational safety, and internal arousal states.
There’s no need to choose once and for all. Good EMDR work is responsive. A therapist may begin with one form of Bilateral Stimulation (BLS) and adjust in real time — based on dissociation, trauma history, or somatic cues from the client.
Table 1 below provides a clinical snapshot of the strengths, applications, and considerations for Eye Movements vs. Tactile Tapping in EMDR. It’s not a ranking — it’s a roadmap.
Ultimately, EMDR is not a rigid script. It’s a process of attunement, adaptation, and trust — in the client, in the relationship, and in the mind’s remarkable capacity to process, integrate, and move forward.
Table 1
Resourcing vs State Change: Why the Difference Matters
Resourcing vs State Change: Why the Difference Matters
This is where two foundational EMDR strategies come into play: resourcing and state change. Though both use BLS, their purpose differs.
State change exercises are short, in-the-moment techniques to help shift from distress to regulation — such as grounding, mindful breathing, or the Butterfly Hug. These are used to anchor the client during difficult material or to close a session.
Resources, on the other hand, are inner strengths that are deliberately installed with BLS — like a “Peaceful Place,” a nurturing figure, or a sense of courage or protection. These internal anchors support emotional resilience and expand the client’s capacity to approach trauma safely.
Tapping plays a role in both — as a bridge between emotional overwhelm and internal calm.
Take Away
Take Away
There’s no single “best” method of bilateral stimulation in EMDR — only what works best for you.
Eye movements may help process trauma more quickly. Tapping might feel safer, gentler, or more grounding. What matters most is flexibility: noticing how your body responds, and adjusting the pace or method as needed.
Healing isn’t a race. It’s a rhythm — one your nervous system learns to move with, calmly, safely, and in its own time.
References
References
Lee, C. W., & Cuijpers, P. (2013). A meta-analysis of the contribution of eye movements in EMDR therapy. Journal of Anxiety Disorders, 27(1), 1–8.
Maxfield, L. et al. (2008). A working memory explanation for the effectiveness of bilateral stimulation. Journal of EMDR Practice and Research, 2(4), 247–261.
Schubert, S. et al. (2008). The efficacy of eye movements and tactile stimulation in EMDR. Journal of EMDR Practice and Research, 2(4), 255–262.
Van den Hout, M., & Engelhard, I. (2012). How does EMDR work? Journal of Experimental Psychopathology, 3(5), 724–738.
Kemp, M. et al. (2010). Tactile BLS and complex trauma. Journal of Trauma & Dissociation, 11(3), 281–292.
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