A crucial component of EMDR is Bilateral Stimulation, which is where some kind of “back and forward” or “left and right” stimulation is produced either in audio or visually.

The client usually either follows some kind of visual object with their eyes, or else has some kind of audio stimulation played to them which alternates between their left and right ears. Which of the two is more effective and commonly used though?

The most commonly used form of bilateral stimulation is the visual form, since it appears in many cases to be the most powerful and effective way of stimulating the mind/brain to process traumatic memories. In some cases audio stimulation can be more effective depending on the nature of the traumatic memory being worked on.

Other forms of stimulation like “tapping” are also sometimes used during the EMDR process. Therapists do have slightly different methodologies on working with trauma and many of them prove to be equally effective.

Regardless of the form of bilateral stimulation used, it has proven to be a very effective way of resolving traumatic memories. Let’s look at the different kinds of BLS and in little more detail and offer some possible reasons as to it’s effectiveness.


Visual Bilateral Stimulation is Generally More Effective and Common

Visual bilateral stimulation in generally the most commonly used nowadays in EMDR therapy, since it appears to produce the most powerful effect in many cases.

It most commonly takes the form of the therapist moving their hand backwards and forwards, left and right, up and down, in front of the patient, getting them to follow it all around with their eyes, whilst they also focus internally on a particular traumatic memory.

For EMDR to be effective there must be this dual focus of attention – just following some kind of visual external stimulus with no internal trauma to focus on is not usually effective, and conversely focusing only on an internal state with no external bilateral stimulation is not effective either.

There has to be this dual focus on both an internal state and an external stimulus for bilateral stimulation to be effective. The therapist has to help the patient, as best they can, stay with both the inner and outer experiences at the same time for the processing to occur.

However, when done correctly, this form of bilateral stimulation in the framework of EMDR therapy has proven to be remarkably effective in helping people resolve traumatic memories, taking the sting out of them and greatly unburdening the client.

When successful, the memory is no longer seen as traumatic, but just as another memory. They can let it go and move on with their lives. In this sense, the use of bilateral stimulation can literally be a life changer for people burdened with distressing memories. Let’s look at the audio component of this.

EMDR Eye Movements

Visual Bilateral stimulation usually involves the therapist moving their hand backwards and forwards in front of the client, getting them to follow it with their eyes

Audio Bilateral Stimulation Can Also Be Used

Audio bilateral stimulation usually consists of some kind of alternating audio stimulation which switches between the left and right ears.

Audio bilateral stimulation can sometimes be more effective if the troublesome memory being worked on has a strong audio component to it that continues to feature prominently in the person’s recollection of it. Some example of this could include:

  • Certain things being said sticks in the person’s memory.
  • Hearing certain triggers words, noises or songs in the present brings them back to the past memory, because these words are also associated in some way with that memory.
  • Intonations and inflections of voice in memories of verbal abuse can stick with the person.
  • Music in the background at the time sticks with them.
  • Loud noises, bangs, explosions associated with the trauma.
  • Any other audio rather than visual aspect to the trauma.

In some of these cases it has been found that using audio rather than visual stimulation can be more effective in “rooting out” these kind of memories with a strong audio component to them. This is discussed briefly in the video above.

There are loads of resources online claiming to have audio recordings of bilateral stimulation which can help with trauma and other things. Many of these are produced by people who are not experts in trauma or psychotherapy so they should be taken with a grain of salt. Some of them may be effective; some may not be.

If you are looking for a recording of bilateral stimulation from an authoritative source trained in trauma and EMDR, then check out the BLS Nature Sounds recording on this page from Australian EMDR therapist Dr James Alexander. The recording is around 20 minutes long and available for just ten dollars.

Why is Bilateral Stimulation So Effective?

Researchers are still not totally sure why EMDR and BLS are so effective and how exactly they work. They just know that it is very effective. There are several leading hypotheses as to why; but none have been proven conclusively. See the video above for discussion of this and also our article on the topic.

In general terms though, it appears that bilateral stimulation is so effective in processing trauma because it provides a distraction for the brain which pulls it out of exclusively focusing on the traumatic memory alone. It gives the patient something else to focus on.

This is the entire idea behind the conept of bilateral stimulation – some kind of external audio or visual stimulus is provided for the person to focus on and follow, whilst also focusing internally on a traumatic memory – the dual focus of attention we mentioned above.

This dual focus of attention appears to blur and distort the traumatic memory, since the mind/brain is also focusing on something else at the same time. The emotional “charge” or “sting” is taken out of it, and it becomes less bothersome and distressing to the person. The short video below summarizes this theory very well.


Another way of looking at this is that having some of kind of stimulation to follow visually left and right, or audibly between the left and right ears, stimulates the left and right sides of the brain in an alternating pattern.

This has the effect of pulling the person out of a purely left brain focus, which can happen when a person is focusing on traumatic memories. It “loosens up” the brain’s perception of the memory and again takes the emotional charge out of it. The mind/brain becomes less fixated on it and can let it go.

In short then, it appears that bilateral stimulation in a sense distracts the mind/brain into letting go of a traumatic memory. The memory is never forgotten; rather the emotional sting is taken out of it so it becomes just another memory and does not bother the person anymore.


  • Mary-Beth Zolik, M.Ed LMHC

    Mary-Beth is a Licensed Mental Health Counselor with a M.Ed in Clinical Mental Health Counseling from the University of Montevallo. Mary-Beth has been in the field of psychology in a variety of roles for the past 20 years.

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