Bilateral Stimulation in EMDR: Eye Movements, Taps, and Tones Explained

9 min read Updated: December 31, 2024

Bilateral stimulation (BLS) is the distinctive element that sets EMDR apart from other therapies. While you focus on a disturbing memory or feeling, alternating stimulation is applied to both sides of your body—most commonly through guided eye movements, but also through taps or audio tones.

This guide explains what bilateral stimulation is, how it works, the different forms it can take, and why it’s so effective for processing trauma and reducing distress.

What Is Bilateral Stimulation?

Bilateral stimulation refers to any form of alternating, rhythmic left-right sensory input. In EMDR therapy, this stimulation occurs while you focus on a target memory, thought, or feeling. The combination of focused attention and bilateral stimulation appears to activate the brain’s information processing system.

Key Characteristics

  • Alternating: Stimulation switches between left and right sides
  • Rhythmic: Occurs at a steady, consistent pace
  • Dual attention: You focus on internal content while tracking external stimulation
  • Brief sets: Applied in sets of 15-30 seconds, followed by breaks

Types of Bilateral Stimulation

Eye Movements (Visual BLS)

The original and most researched form of bilateral stimulation involves following a moving target with your eyes while keeping your head still.

How it’s done:

  • Therapist moves their fingers side to side about 12-14 inches from your face
  • You follow the movement with your eyes
  • Can also use a light bar, moving dot on a screen, or apps like EMDR4LIFE

Advantages:

  • Most extensively researched form of BLS
  • Easy to implement
  • Provides clear, trackable stimulation
  • Can be done with simple tools or apps

Tactile Stimulation (Tapping)

Alternating physical taps or vibrations on both sides of the body.

Common methods:

  • Therapist taps alternately on your hands or knees
  • Self-administered “butterfly hug” (crossing arms and alternating taps on shoulders)
  • Handheld tappers/pulsers that vibrate alternately
  • Smartphone vibration patterns

Advantages:

  • Good for people who find eye movements uncomfortable
  • Can be done with eyes closed
  • Allows for more internal focus
  • Self-tapping can be used independently

Auditory Stimulation (Tones)

Alternating sounds played to each ear through headphones.

How it works:

  • Tones or clicks alternate between left and right ears
  • Creates a side-to-side auditory experience
  • Often combined with other forms of BLS

Advantages:

  • Good for people with visual difficulties
  • Can be very calming
  • Easy to use during teletherapy
  • Pairs well with eyes-closed processing

How Bilateral Stimulation Works: The Science

Researchers have proposed several theories for why bilateral stimulation is effective. The truth likely involves multiple mechanisms working together.

Working Memory Theory

This leading theory suggests that:

  • Working memory has limited capacity
  • When you hold a memory in mind AND track eye movements, the dual task taxes working memory
  • This causes the memory to become less vivid and emotionally intense
  • The memory is then reconsolidated in a less disturbing form

Research strongly supports this theory. Studies show that eye movements reduce the vividness and emotionality of memories more than other comparison tasks.

Interhemispheric Communication

Another theory proposes that bilateral stimulation:

  • Enhances communication between brain hemispheres
  • Activates both sides of the brain in rhythm
  • May help integrate emotional (right hemisphere) and rational (left hemisphere) processing

REM Sleep Connection

The eye movements in EMDR resemble those occurring during REM sleep, when:

  • Memory consolidation occurs
  • Emotional processing happens
  • Traumatic material may be integrated

Some researchers suggest EMDR may engage similar mechanisms to those active during REM sleep.

Orienting Response

Bilateral stimulation may trigger an investigative or “orienting” response:

  • The brain shifts into an alert, exploratory state
  • This reduces the defensive/fear response
  • Creates optimal conditions for memory reconsolidation

Parasympathetic Activation

Studies show bilateral stimulation can:

  • Decrease heart rate
  • Reduce skin conductance (stress indicator)
  • Activate the relaxation response
  • Lower overall physiological arousal

This calming effect may create a safer internal environment for processing difficult material.

Research on Bilateral Stimulation Effectiveness

Does the Type Matter?

Research generally shows:

  • Eye movements have the most research support
  • Other forms (taps, tones) also appear effective
  • The alternating, bilateral nature seems more important than the specific modality
  • Individual preference may matter—some people respond better to certain types

Key Findings

  • Eye movements reduce memory vividness and emotionality even in single sessions
  • Effects persist over time—memories stay less disturbing
  • Bilateral stimulation adds effectiveness beyond just exposure to the memory
  • The working memory hypothesis is supported by multiple studies

Using Bilateral Stimulation at Home

While full EMDR therapy requires a trained professional, bilateral stimulation can be used independently for general stress relief and emotional regulation.

Appropriate Self-Use

  • Stress reduction: Calming your nervous system during anxious moments
  • Relaxation practice: As part of a regular wellness routine
  • Mild disturbances: Processing minor upsets before they accumulate
  • Resource strengthening: Enhancing positive memories and feelings
  • Sleep preparation: Calming racing thoughts before bed

What to Avoid Without a Therapist

  • Processing traumatic memories
  • Targeting highly disturbing material
  • Treating clinical PTSD or other conditions
  • Extended processing without professional support

Self-Guided Techniques

Using an App

Apps like EMDR4LIFE provide visual bilateral stimulation you can follow on your phone or computer. Simply:

  1. Open the app and start a session
  2. Follow the moving ball with your eyes
  3. Notice your breathing and any shifts in how you feel
  4. Continue for 2-5 minutes or until you feel calmer

Butterfly Hug

A self-administered technique:

  1. Cross your arms over your chest, hands on opposite shoulders
  2. Alternately tap your left and right shoulders
  3. Keep a slow, steady rhythm
  4. Focus on your breath or a calming image

Knee Tapping

While seated:

  1. Rest your hands on your knees
  2. Alternate tapping left and right knees
  3. Maintain a steady rhythm
  4. Notice any sensations or shifts

Optimizing Your Experience

Speed of Stimulation

  • Fast speed (1+ Hz) may be more activating/processing
  • Slow speed may be more calming
  • Adjust based on what feels right and your goals

Duration

  • Sets typically last 15-30 seconds
  • Multiple sets with brief pauses between
  • Total session can range from 2-20+ minutes

Environment

  • Quiet, private space is ideal
  • Comfortable seating position
  • Minimize distractions
  • Have grounding techniques available if needed

Getting Started

Ready to experience bilateral stimulation?

Bilateral stimulation is a simple yet powerful tool. Whether as part of professional EMDR therapy or self-guided practice, it can help calm your nervous system and support emotional processing.