What is Bilateral Stimulation?

Bilateral stimulation is stimuli (visual, auditory or tactile) which occur in a rhythmic left-right pattern. For example, visual bilateral stimulation could involve watching a hand or moving light alternating from left to right and back again. Auditory bilateral stimulation could involve listening to tones that alternate between the left and right sides of the head. Bilateral stimulation is a treatment element of EMDR. It was discovered accidentally by Francine Shapiro Phd as she was walking in a park in the late 1980’s. As she was walking Shapiro She noticed that some distressing feelings she was having about a particular situation suddenly ceased. When she reflected back on what happened, she remembered that she had experienced some spontaneous saccadic eye movements (kind of rapid blinking). This led her to experiment further and the discovery that when a person deliberately focuses on a distressing memory, and then concentrates on bilateral stimulation, their distress is reduced. Moreover, the distressing memory seems to become less distressing in a long-term way. This discovery led to the development of EMDR.

What does bilateral stimulation do?

Bilateral stimulation is a core treatment element of EMDR and a process which distinguishes EMDR from any other method. While there is still a lot to learn about this amazing process, it can be said that it produces four main effects;
1.    A relaxation effect including decreased physiological arousal.
2.    Increased attentional flexibility (meaning that your thoughts become less ‘stuck’ on whatever was bothering you).
3.    Distancing effect (meaning that the problem seems smaller and further away).
4.    Decreased worry.

These effects are experienced as a ‘bottom-up’ cascade of changes meaning that they are experienced in the lower areas of the brain first, as a physiological response (ie; decreased tension) then travel ‘up’ the brain leading to mental changes (eg; decreased worry). Because this order works with how the brain normally processes information, the effects are often experienced more quickly and easily than with say top-down strategies such as insight and conscious introspection.

How does bilateral stimulation work?

There are many theories regarding how bilateral stimulation works. My favourite involves the orienting reflex. The orienting reflex is simply the natural tendency for your nervous system to orient itself to new stimuli. The evolutionary implications of this are obvious – is that rustling sound a sabre-toothed tiger or just the wind in the grass? So when your nervous system is subject to bilateral stimulation, your attention is naturally diverted to that, and whatever was in your mind before gets shunted to one side. Normally after a few moments, once your brain realizes you’re not facing a sabre-toothed tiger, your attention returns to the previous subject. This also known as habituation – habituation is when we cease responding to a stimuli.
Habituation does not occur with bilateral stimulation – your brain just can’t turn away from it (some people actually find this a bit irritating but hey, take your pick). As a result of your attention being held captive by the bilateral stimulation, two things happen.  1) You can’t think of the problem and 2) you start to feel relaxed. This leads to changes in the way the memory of the problem is stored through what’s known as  non-associative learning. Nonassociative learning is a change in a response to a stimulus that does not involve associating the presented stimulus with another stimulus or event such as reward or punishment.[4] (Examples of associative learning include classical conditioning and operant conditioning).

Is Bilateral stimulation safe?

For most people bilateral stimulation is distracting and relaxing and perfectly safe. However, because it involves direct sensory stimulation of the nervous system, bilateral stimulation can trigger unexpected responses in people with conditions which involve hypersensitivity to sensory stimuli, Eg; people with acquired brain injury (where the condition involves sensitivity to complex visual or auditory stimuli), migraine sufferers (usually when they have the migraine), people with complex PTSD, people with Dissociative Identity Disorder (where different ego states may be activated by sensory changes). People with these kinds of conditions are not advised to use this process without the guidance of a trained EMDR therapist. These can be located via your local EMDR association or a Google search. For example, in the US its http://www.emdria.org/displaycommon.cfm?an=1&subarticlenbr=235. In Australia its http://emdraa.org/

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