SUD and VoC: how to use EMDR's two scales
Two short questions run through every EMDR session: “How disturbing does it feel now?” and “How true do those words feel?” The answers, the SUD and VoC ratings, tell you where processing stands, when to move to the next phase and whether a target is really finished. This guide explains both scales and how to use them well, including online.
The SUD scale (0–10)
SUD stands for Subjective Units of Disturbance. The scale comes from behaviour therapy: Joseph Wolpe developed it to rank feared situations during systematic desensitisation, on a scale from 0 to 100. EMDR uses a 0 to 10 version, from 0 (no disturbance, neutral) to 10 (the highest disturbance you can imagine).
A typical way to ask, once the client has the image, the negative cognition and the emotion in mind:
“On a scale from 0 to 10, where 0 is no disturbance or neutral and 10 is the highest disturbance you can imagine, how disturbing does it feel to you now?”
Two details matter. The rating is about how the memory feels now, not how bad the event was at the time. And it is about the memory as a whole as it is activated, not one isolated detail.
The VoC scale (1–7)
VoC stands for Validity of Cognition. Francine Shapiro introduced it in her first controlled study of the method, published in 1989 in the Journal of Traumatic Stress. It measures how true the positive cognition feels at a gut level, from 1 (completely false) to 7 (completely true).
“When you think of that picture, how true do the words ‘I can protect myself now’ feel to you now, from 1, completely false, to 7, completely true?”
Ask for a felt sense, not an intellectual judgement. Many clients know the positive statement is logically true; the VoC asks how true it feels.
When to check each scale
| Phase | SUD | VoC |
|---|---|---|
| 3 Assessment | Baseline rating of the target | Baseline rating of the positive cognition |
| 4 Desensitisation | When you return to the target and the client's reports have become neutral or positive | – |
| 5 Installation | – | After each set, aiming for 7 |
| 8 Reevaluation | At the start of the next session | Has the positive cognition held? |
During desensitisation you don't ask for a SUD after every set. Asking too often pulls the client out of processing and into evaluating. Check it when the associations seem to have settled and you go back to the target.
When is a target finished?
- SUD 0 is the goal of desensitisation. A SUD of 1 can be accepted when a small residual disturbance is ecologically valid, for example some sadness about a real loss.
- VoC 7 is the goal of installation. If it stays at 6 or lower, ask what keeps it from being completely true. The answer often points to a blocking belief or another memory that needs its own work.
- A clear body scan confirms the result.
Be careful with a SUD that drops very fast, especially in a client who wants to please or who tends to dissociate. A low number together with a tense body or a flat voice deserves a closer look.
When the numbers don't move
- The SUD stays high after several sets with no new material: processing may be looping. Change the direction, speed or type of bilateral stimulation, or use a cognitive interweave.
- The SUD goes up: this is common early in processing, as the memory becomes more vivid. Keep going as long as the client stays within their window of tolerance and is aware of the present as well as the memory.
- New memories keep coming up: the client may have moved into another memory network. Note them as possible future targets and return to the original one.
- The VoC stays low: look for a blocking belief (“If I let this go, it means it didn't matter”), or check whether the positive cognition is realistic.
Asking for ratings online
- Stop the stimulus before you ask, so the client can look at you on the video call.
- Some clients find it hard to say a number. They can show it with their fingers, or point to a spot on a line drawn on paper.
- With bilingual clients, agree which language you use for the target and the scales. A memory can feel different depending on the language (see EMDR in a second language).
- Write the ratings down straight away. With a free Remote EMDR account you can keep them as notes in the patient's dossier, next to the session history.