Types of Bilateral Stimulation in EMDR Therapy: What They Are and How They Work

Understanding eye movements, tapping, tactile stimulation, and auditory bilateral stimulation in EMDR therapy

When people first hear about EMDR therapy, they often associate it with one thing: moving the eyes back and forth while thinking about a difficult memory. Eye movements are certainly one of the best-known features of Eye Movement Desensitization and Reprocessing therapy, but they are not the only form of stimulation that may be used. EMDR therapists may use several forms of alternating sensory stimulation, commonly referred to as bilateral stimulation, or BLS. Depending on the client, the phase of treatment, and the clinical purpose, this may include guided eye movements, alternating tactile stimulation, handheld pulsers, tapping, or alternating auditory tones.

Bilateral stimulation is an important component of EMDR, but it is also one of the most misunderstood parts of the therapy. BLS is not a stand-alone treatment, it does not simply “activate both sides of the brain,” and its purpose is not merely to calm the nervous system. To understand why therapists use it, it helps to look at how bilateral stimulation fits within the larger EMDR protocol and what research suggests about its effects on memory.

What Is Bilateral Stimulation in EMDR Therapy?

In EMDR therapy, bilateral stimulation refers to alternating visual, tactile, or auditory input while a client simultaneously attends to aspects of a targeted memory or another therapeutic focus. EMDRIA describes this as dual attention bilateral stimulation, because part of the client’s attention remains connected to the targeted material while another part remains engaged with stimulation occurring in the present.

This distinction is important. EMDR is not simply exposure to a traumatic memory while someone watches a moving light or listens to alternating sounds. It is a structured psychotherapy that includes history taking, preparation, assessment, reprocessing, installation of adaptive beliefs, body awareness, closure, and reevaluation. Bilateral stimulation is used within that broader clinical framework rather than functioning as the therapy by itself.

During the reprocessing phases of EMDR, a therapist may ask a client to briefly notice an image, thought, belief, emotion, or physical sensation connected to a distressing experience. Sets of bilateral stimulation are then introduced, followed by pauses in which the client notices what comes to mind. Over time, the experience may become less vivid, less emotionally intense, or connected with new associations and perspectives.

Why Is Bilateral Stimulation Used in EMDR?

There is still ongoing scientific discussion about exactly how EMDR produces therapeutic change. It is therefore more accurate to talk about proposed mechanisms than to claim that bilateral stimulation has one established neurological explanation.

One of the best-supported explanations for the eye-movement component is the working memory account. Working memory has limited capacity. When a person holds a vivid distressing memory in mind while simultaneously performing another task that also requires attention, such as making rapid eye movements, those two tasks compete for working-memory resources.

Experimental research has found that recalling an unpleasant autobiographical memory while making eye movements can reduce later ratings of its vividness and emotional intensity. Importantly, studies have also found support for a working-memory explanation rather than the popular idea that horizontal eye movements work simply because they increase communication between the brain’s left and right hemispheres.

This may help explain why a person can still remember what happened after EMDR while experiencing the memory differently. The goal is not amnesia. Clients generally continue to know what occurred, but the memory may become less emotionally immediate, less vivid, or less likely to produce the same level of distress when recalled.

Eye Movements

Eye movements are the most recognizable and most extensively studied form of bilateral stimulation used in EMDR. A therapist may move two fingers from side to side while the client follows them visually. Some clinicians use a light bar or another visual target that moves horizontally across the client’s field of vision. In telehealth EMDR, visual bilateral stimulation can also be created through appropriately designed digital tools.

Research examining eye movements during memory recall has repeatedly found reductions in the vividness and emotional intensity of distressing autobiographical memories. Experimental studies suggest that the attentional demands of the eye-movement task may be an important part of this effect.

Speed and other characteristics of the eye movements may also influence how demanding the task is on working memory. This is one reason EMDR therapists adjust bilateral stimulation during treatment rather than assuming one speed or presentation is appropriate for every client.

Eye movements are not comfortable or practical for everyone, however. Some clients experience visual fatigue, headaches, dizziness, difficulty tracking, or simply prefer another form of bilateral stimulation. In those cases, tactile or auditory approaches may be considered.

Alternating Tactile Stimulation

Tactile bilateral stimulation uses alternating physical sensations on the left and right sides of the body. This may involve gentle tapping on the hands, knees, shoulders, or another appropriate location. Some therapists use small handheld devices, often referred to informally as tappers or pulsers, which alternate vibration between the left and right hands.

Tactile stimulation is common in clinical EMDR practice, particularly for clients who find eye movements uncomfortable or distracting. It can also be useful in telehealth settings when the client has access to appropriate equipment or can comfortably use therapist-guided self-tapping.

The research base for tactile stimulation is smaller than the research base for eye movements, so it is important not to assume that every form of tactile BLS works through exactly the same mechanism or produces identical effects.

A 2026 experimental study examined alternating vibratory bilateral stimulation while healthy participants recalled negative autobiographical memories. Vibratory stimulation prevented the increase in emotionality that occurred during repeated recall in the control condition, although it did not significantly reduce memory vividness. The authors described the findings as encouraging while also recognizing that more research is needed.

Earlier clinical research comparing different auditory and kinesthetic stimulation patterns within EMDR also found symptom improvement across stimulation conditions, with some evidence suggesting an advantage for alternating stimulation during certain portions of treatment. Because that study was small, it should be interpreted as preliminary rather than definitive evidence that one tactile method is superior.

Handheld EMDR Tappers

Handheld tactile pulsers are one way therapists provide alternating bilateral stimulation without requiring continuous visual tracking. The client usually holds one device in each hand while the therapist controls the alternating rhythm, speed, and intensity. Some clients prefer this method because they can close or soften their eyes and attend more easily to the internal material that arises during processing.

At Acadia Psychotherapy & Associates, small handheld tactile devices may be used when appropriate and when they fit the client’s preferences and treatment plan. They are simply one option within the EMDR protocol rather than a special or inherently more powerful version of EMDR. As with other forms of BLS, the therapist continues monitoring the client’s level of distress, attention, associations, and ability to remain engaged in the process.

Alternating Auditory Stimulation

Auditory bilateral stimulation typically involves sounds or tones that alternate between the left and right ears, usually through headphones. Some people prefer auditory BLS because it requires less visual or physical engagement than eye movements or tapping. It may also be useful when other sensory methods are uncomfortable or inaccessible. However, the assumption that all BLS methods are interchangeable is not supported by the research.

In one experimental study, eye movements taxed working memory more effectively than alternating auditory beeps and produced greater reductions in the vividness of negative memories. This does not mean auditory BLS has no clinical role, but it does illustrate why clinicians should avoid claiming that every form of bilateral stimulation has been shown to produce the same effects. The choice of stimulation should therefore be based on clinical judgment, the client’s needs and preferences, the purpose of the intervention, and the therapist’s training rather than the assumption that all bilateral techniques are neurologically equivalent.

The Butterfly Hug and Self-Tapping

The Butterfly Hug is a form of alternating self-tapping in which the arms are crossed over the chest and the person alternates gentle taps from side to side. Other variations may involve alternating taps on the knees, thighs, or shoulders. These practices may be used in EMDR-informed preparation, grounding, stabilization, or resource-building exercises. In some contexts they are also incorporated into EMDR protocols.

It is important, however, to distinguish between using alternating tapping as a grounding or resourcing technique and conducting full trauma reprocessing. Watching a bilateral-stimulation video or tapping from side to side while thinking about a traumatic experience is not the same as participating in EMDR therapy. EMDR involves clinical assessment, preparation, target selection, monitoring of distress, attention to dissociation and other factors, and structured closure. The therapist also adjusts the process based on how the client responds. EMDRIA describes EMDR as an eight-phase psychotherapy in which bilateral stimulation occurs within a larger treatment process. For that reason, I generally distinguish between simple self-regulation practices that a client has been taught to use independently and trauma processing that is occurring within therapy.

Is Bilateral Stimulation Supposed to Calm the Nervous System?

Not necessarily. Some people find rhythmic eye movements, tapping, or tactile stimulation calming. Other people experience increased emotion, physical activation, images, memories, or unexpected associations during EMDR processing. That does not mean something has gone wrong.

During trauma processing, the purpose of bilateral stimulation is not simply to make the client feel relaxed. The client may move through periods of distress as different aspects of the memory become accessible. The therapist monitors the process and helps the client remain oriented to the present while allowing processing to unfold within a tolerable range.

This is one reason I am careful with the common social-media description of BLS as a technique that automatically “regulates the nervous system.” Regulation can be part of the experience, particularly during preparation and resourcing, but bilateral stimulation has a broader role within EMDR than simply producing calm.

Does Bilateral Stimulation Activate the Left and Right Sides of the Brain?

The phrase “bilateral” understandably leads people to assume that the therapeutic effect occurs because stimulation alternates between the brain’s left and right hemispheres. That explanation is appealing, but it is much more certain than the science allows.

Research comparing horizontal and vertical eye movements has found similar effects on the vividness and emotional intensity of memories, which does not support a simple interhemispheric explanation. Working-memory competition currently has stronger experimental support as one explanation for the effects of eye movements during memory recall.

There are also physiological and neurobiological theories about EMDR that continue to be investigated. At this point, it is more responsible to say that the mechanism is still being studied than to tell clients that bilateral stimulation definitively “integrates the two sides of the brain.”

Is Bilateral Stimulation Similar to REM Sleep?

You may also hear bilateral eye movements compared with the rapid eye movements that occur during REM sleep. There are theoretical similarities that have led researchers to explore this possibility, but EMDR should not be described as recreating REM sleep or putting the brain into a REM-like state. That explanation goes beyond what has been established.

During EMDR, the client is awake, oriented to the present, and intentionally attending to specific therapeutic material while completing a dual-attention task. The process is clinically structured and very different from naturally occurring sleep. I prefer to explain what we know rather than use a neuroscience analogy simply because it sounds compelling.

Which Type of Bilateral Stimulation Is Best?

There is no single form of bilateral stimulation that is automatically best for every client. Eye movements have the strongest direct experimental research base and are central to the original EMDR procedure. At the same time, tactile and auditory approaches are commonly used in practice when clinically appropriate. A therapist may consider several factors when choosing or adjusting BLS, including the client’s comfort, visual tolerance, sensory preferences, ability to maintain dual attention, physical accessibility, telehealth setting, and response during processing.

A client may also respond differently to different forms of stimulation at different points in treatment. Clinical flexibility is useful, but it should not become an excuse to make unsupported claims. If an alternative BLS method is used, it is reasonable to acknowledge that the evidence supporting that specific method may not be as extensive as the evidence supporting eye movements.

What Does Bilateral Stimulation Feel Like During EMDR?

The experience varies considerably from one person to another. During a set of bilateral stimulation, you may notice memories, images, physical sensations, emotions, beliefs, or associations emerging. Sometimes the connection between one thought and the next is obvious. At other times, something seemingly unrelated may come to mind.

The therapist generally does not require you to analyze every association while the processing is occurring. Instead, you are encouraged to notice what arises and allow the process to continue. After a set, the therapist may ask what you noticed and then use that information to guide the next part of the protocol.

Some clients describe memories becoming more distant or less vivid. Others notice a shift in emotion, a new perspective, a change in a body sensation, or a belief that begins to feel different. EMDRIA notes that clients may experience changes in images, feelings, thoughts, or beliefs as sets of eye movements, sounds, or taps continue. The process is not identical for everyone, and clients remain able to pause or stop at any point.

Bilateral Stimulation Is Only One Part of EMDR Therapy

This may be the most important point of the entire discussion. Bilateral stimulation is not EMDR. EMDR is a comprehensive psychotherapy model. BLS is one procedure used within that model. Focusing exclusively on the eye movements, tapping, tones, or tappers can make EMDR appear much simpler than it actually is. Effective EMDR treatment also depends on appropriate assessment, case conceptualization, preparation, target selection, pacing, monitoring, reevaluation, and the therapeutic relationship. This distinction becomes particularly important when EMDR content is presented online. Bilateral-stimulation videos, apps, audio tracks, and tapping exercises may resemble one component of EMDR, but they do not reproduce the complete treatment protocol.

What the Research Suggests

The research on bilateral stimulation is more nuanced than either of the extremes often presented online. It would be inaccurate to say that BLS has no meaningful role in EMDR. Experimental studies have repeatedly demonstrated that eye movements performed during memory recall can reduce the vividness and emotional intensity of distressing autobiographical memories, and working-memory competition offers a plausible explanation for at least part of that effect.

It would be equally inaccurate to claim that every form of bilateral stimulation has been proven to work identically or that alternating stimulation simply “rewires the brain.” Research comparing eye movements with auditory stimulation has found meaningful differences between modalities, while emerging research on vibratory bilateral stimulation suggests potential effects that still require further investigation. The responsible position is somewhere in between: bilateral stimulation is an important feature of EMDR, eye movements have a meaningful experimental evidence base, alternative forms are used clinically, and the mechanisms and comparative effects of different BLS modalities continue to be studied.

EMDR Therapy in McKinney, Texas

At Acadia Psychotherapy & Associates, EMDR therapy is individualized rather than delivered as a one-size-fits-all procedure. The form of bilateral stimulation we use depends on the client, the treatment plan, and how the person responds during the process. EMDR may be considered when distressing memories, triggers, beliefs, or emotional and physical reactions continue to affect the present. Before beginning reprocessing, we spend time understanding your history, identifying treatment goals, and making sure there is adequate preparation for the work. In-person EMDR therapy is available at our office in McKinney, Texas, with secure online EMDR therapy available to adults throughout Texas.

Learn more about EMDR Therapy in McKinney, Texas.

About the Author

Elizabeth Boyer, LMFT, is a licensed marriage and family therapist and EMDR-trained clinician in McKinney, Texas. She is the founder of Acadia Psychotherapy & Associates and works with adults experiencing trauma-related symptoms, anxiety, chronic stress, burnout, relationship distress, and other concerns using an individualized, trauma-informed approach.

References

Armand, C., Guillaume, F., & Rey, A. (2026). Can vibratory bilateral stimulation reduce the emotionality and vividness of negative autobiographical memories? Journal of Behavior Therapy and Experimental Psychiatry, 91, 102090.

Gunter, R. W., & Bodner, G. E. (2008). How eye movements affect unpleasant memories: Support for a working-memory account. Behaviour Research and Therapy, 46(8), 913-931.

Servan-Schreiber, D., Schooler, J., Dew, M. A., Carter, C., & Bartone, P. (2006). Eye movement desensitization and reprocessing for posttraumatic stress disorder: A pilot blinded, randomized study of stimulation type. Psychotherapy and Psychosomatics, 75(5), 290-297.

van den Hout, M. A., Engelhard, I. M., Rijkeboer, M. M., Koekebakker, J., Hornsveld, H., Leer, A., Toffolo, M. B. J., & Akse, N. (2011). EMDR: Eye movements superior to beeps in taxing working memory and reducing vividness of recollections. Behaviour Research and Therapy, 49(2), 92-98.

Disclaimer: This information is for educational purposes only and is not a substitute for individualized therapy.