Research notes · Updated Mar 2026

What we read, and why we build it the way we do.

TheraJoy is built on a small, conservative reading of the bilateral-stimulation literature — and a clear line about what our tool is and isn't. This page is the reading list. It is not clinical guidance.

What we claim, and what we don't.

TheraJoy generates a rhythmic left-right stimulus — visual, haptic, or audio — at a frequency the user controls. That's it. We make no claim that this process treats trauma, PTSD, anxiety, depression, or any other condition.

Clinicians using EMDR and related trauma-focused approaches have, for three decades, integrated bilateral stimulation into structured protocols. Those protocols do not reduce to the stimulus itself, and our app is not a substitute for any of them.

In one sentenceTheraJoy is a metronome for your nervous system — useful, by report, for many people, and nothing like a treatment.

The bilateral-stimulation literature.

Bilateral alternating stimulation (BLS) is the rhythmic left-right cue central to EMDR's "dual-attention" phase. Its active mechanism is disputed: proposed explanations include working-memory taxation (the "taxation" hypothesis), orienting response activation, and parasympathetic entrainment. The literature does not converge on one.

What the literature does agree on: BLS is safe, well-tolerated in clinical settings, and — as one component of a therapist-led protocol — associated with measurable benefit in studies of trauma-focused care.

We read the following as our ground floor:

Shapiro, F. (2018). Eye Movement Desensitization and Reprocessing (EMDR) Therapy: Basic Principles, Protocols, and Procedures (3rd ed.)
Guilford Press · Book
The foundational text. Chapter 3 ("Mechanisms of action") is the most honest inventory of what we do and don't know about why bilateral stimulation seems to help. We re-read it every quarter.
Lee, C. W., & Cuijpers, P. (2013). A meta-analysis of the contribution of eye movements in processing emotional memories.
Journal of Behavior Therapy and Experimental Psychiatry · Meta-analysis
A careful meta-analysis of the "does the eye movement actually matter?" question. Finds small but significant effects attributable to the bilateral component, beyond exposure alone.
van den Hout, M. A., et al. (2011). Dual-task interventions for PTSD.
Journal of Behavior Therapy and Experimental Psychiatry · Review
Argues for the "working-memory taxation" hypothesis: any demanding concurrent task (not just eye movements) can reduce the vividness of distressing memories. Bilateral stimulation is one convenient implementation of that.
de Voogd, L. D., & Phelps, E. A. (2020). A cognitively demanding working-memory intervention reduces reactivity to aversive memories.
Neurobiology of Learning and Memory · Primary research
A recent, well-controlled replication of the dual-task effect. Reinforces that the specific modality (eye movement, tapping, tone) matters less than the rhythmic, attention-splitting structure.

Why haptic, not visual.

We default to haptic stimulation (vibration in alternating hands) for three practical reasons:

  • Eyes-closed self-use. The most common way someone reaches for TheraJoy on their own is with eyes shut. A visual orb works for modes like Ambient, but haptic is the baseline that still functions in the bath, on a plane, or before sleep.
  • Less visually stimulating. Many people report light sensitivity around anxious or dysregulated states. A small, private vibration asks less.
  • Clinically consistent with "tappers." Handheld tactile devices ("tappers") have been a standard part of EMDR practice since the late 1990s. A pair of Joy-Cons is a surprisingly good implementation of that hardware idea.

Whichever mode you run, the device drives at the same underlying frequency — so a preset built on Orb feels identical on Horizon and on AirPods haptics.

Speed, dose, timing.

We expose three parameters: speed (0.3 – 1.5 Hz), intensity (1–10), and dose (time or pass count). The defaults are conservative.

Speed

Published EMDR protocols commonly describe "one to one-and-a-half cycles per second" for reprocessing sets. For resourcing and self-regulation, slower is often reported as calmer. We default to 0.9 Hz, which tends to feel like "a little slower than a walking pace."

Dose

Between-session self-use in published protocols ranges from 30-second "container" passes to 3-minute calm-place installations. TheraJoy defaults to 24 passes (≈ 27 seconds at 0.9 Hz) per set — short enough to be repeatable, long enough to settle.

What we explicitly don't do

  • We do not let clients run sustained stimulation during trauma recall on their own. Our longest single-block preset is 3 minutes.
  • We don't "push" intensity over time. The app never increases stimulation on its own.
  • We don't quantify "progress." No streaks, no charts, no score.

Self-use versus clinical use.

For an individual using TheraJoy on their own, we recommend it for resourcing and grounding — that is, strengthening felt-sense access to calm or safety. Think: closing your eyes, recalling a grounded memory, and letting a slow haptic rhythm move underneath that memory. Many users report that becomes easier to reach with practice.

We do not recommend solo reprocessing of traumatic material. Reprocessing is the work done with a trained clinician, with a full protocol and a container. No app can replace that, and we have built this one specifically to not try.

"The machine is never the therapy. The machine is just a metronome — the therapist is the musician."
— paraphrased from an early EMDR training tape, 1994

Glossary.

BLS
Bilateral stimulation — any rhythmic left-right cue (visual, haptic, or audio).
Dual attention
The state of holding an internal experience (memory, feeling) while also tracking an external stimulus.
Resourcing
The practice of strengthening access to a calm, safe, or positive internal state — often the first phase of trauma-focused work.
Reprocessing
The therapist-led phase in EMDR where distressing memories are revisited with dual-attention stimulation. Not what TheraJoy is for.
Container
A resourcing technique: mentally "putting away" distressing material until the next session. Often cued with short BLS sets.
Pass
One left-right or right-left movement. A full cycle is two passes.

One more time, clearly.

TheraJoy is a consumer wellness tool. The content of this page is a summary of published research made available for transparency. It is not medical, clinical, or therapeutic advice. If you are experiencing significant distress, please contact a licensed clinician or your local emergency line.

If you're a clinician and you spot something here that needs correcting or nuancing, please email us. We'd like to be corrected.