EMDR is a psychotherapeutic approach recommended by the World Health Organization (WHO) for the treatment of disorders such as post-traumatic stress disorder, anxiety, depression and, more generally, psychological distress. In all these disorders, intrusions are one of the symptoms leading to intense emotional distress. EMDR therapy, by making intrusions less emotional and less present in the mind (i.e. less vivid), would reduce psychological distress. This symptomatological reduction would be made possible by the therapist's application of alternating bilateral visual (rapid eye movements following a point from left to right), auditory (tones emitted alternately in the right ear and then in the left ear) and/or tactile (tapping with fingers on the left and right shoulders alternately) stimulations administered while the patient concentrates on his or her intrusive thoughts. Accordingly, the aim of this research is to investigate the efficacy of self-administration of Alternating Bilateral Stimulations (ABS), on the emotional intensity (emotionality) associated with negative intrusive thoughts (or intrusions).

Intrusive thoughts (or intrusions) are recognized as being particularly vivid and emotionally "charged", and constitute one of the transdiagnostic symptoms of numerous disorders such as Post Traumatic Stress Disorder (PTSD), anxiety and depression.

Numerous studies have demonstrated that it is now possible to modulate the persistence of intrusions in memory, as well as their emotional impact, through Eye Movement Desensitization and Reprocessing (EMDR) therapy. EMDR is based on the administration of visual, auditory (sound) or sensory (tapping) Alternating Bilateral Stimulations (ABS). These ABS, which can be self-administered by the patient during the Memory Activation (MA) of an intrusive thought, would reduce the emotionality and vividness of the intrusive symptoms and decrease the associated physiological reactivity.

Recent research claims that the mechanisms of action of ABS involve a joint articulation of both neurobiological (Memory Consolidation/Reconsolidation (M-C/R) and psychological (Working Memory (WM)) theories.

Memory consolidation refers to the transfer of a newly acquired memory trace into WM (fragile and susceptible to forgetting) and its stabilization in Long-Term Memory (LTM). Consolidation involves two processes. The first, synaptic consolidation, requires the triggering of molecular processes operating within a time window of between 10 minutes and 6 hours. The second, called systemic consolidation, can extend over years and takes place mainly during the sleep cycle. Reconsolidation implies that an intrusion, when activated in WM, becomes labile again and must subsequently be consolidated again (reconsolidated) in LTM. A permanent memory can thus be revived, then degraded, notably by the administration of ABS likely to interfere with its reconsolidation in memory.

Working memory (WM) refers to a memory system that enables the temporary retention and processing of information needed to perform complex cognitive tasks. capacity is limited. In fact, the competition of two simultaneous tasks (e.g. BAS administration during the memory activation (MA) of an intrusive thought) implies, in a consequential way, an alteration in its storage performance, as well as a decrease in the emotional load associated with the intrusion. In other words, while WM remains the strongest lead to date, it can only be considered in conjunction with M-C/R theory.

From a clinical/experimental protocol point of view, this link implies compliance with a number of criteria. The first is the temporal criterion for ABS administration (between 10 minutes and 6 hours post-MA), as well as the quantitative criterion relating to the number of MAs (not to exceed 4 MAs). In other words, the application of an interventional methodology that does not meet all these criteria (i.e., administration of ABS performed outside the M-C/R time window and repeated MA of the same intrusion) would induce the involvement of a third process, namely the extinction process. In one study, the application of an extinction protocol performed within the consolidation window (a paradigm known as Retrieval Extinction (P-R/E)) also induced a modification of the initial memory trace. It would therefore seem appropriate to consider the adoption of a tri-processual integrative model involving the joint articulation of Working Memory (WM), Memory Consolidation/Reconsolidation (C/R-M) and the Retrieval Extinction Paradigm (P-R/E). This is why we propose to study, in this research , the role of the application of this tri-processual theoretical modeling on the emotionality and vividness associated with intrusions, as well as on their psychophysiological and psychopathological consequences. Through the use of new technologies, these methodologies could complement conventional psychotherapeutic treatments which, through the self-administration of ABS, could add up and, in fact, potentiate the effectiveness of psychotherapy.

Inclusion Criteria:

• Present symptoms of acute stress (score between 22 and 35 on the Impact Event Scale-Revised, IES-R) and/or PTSD (higher score or equal to 36 on the IES-R), but at least present moderate to high psychological distress (score equal to or greater than 8 on the Kessler Abbreviated Psychological Distress Scale, K6);
• Being in need of psychotherapeutic follow-up but not having started it yet;
• Be aged between 18 and 65 years inclusive;
• Speak and write French (be able to understand information and complete questionnaires independently);
• Have good vision (being able to follow the movement of a white point on a screen);
• Have good hearing and tactile abilities (being able to perceive auditory and tactile tones);
• Have a computer equipped with a webcam;
• Be informed and sign informed consent.

Exclusion Criteria:

• Be an adult protected under guardianship or curatorship;
• Be a person subject to a judicial safeguard measure;
• Present a lack of autonomy implying an impossibility in terms of administering questionnaires and filling out questionnaires;
• Have a vision defect implying an impossibility of visual tracking of a white dot;
• Present a hearing defect and/or tactile abilities implying an impossibility of perception;
• Have a neurological condition constituting measurement biases (muscular dysfunctions, perceptual dysfunctions, etc.);
• Suffer from psychotraumatic and dissociative disorders of complex type (respectively evaluated with regard to the anamestistic data of the patients and with a score greater than 25 on the dissociative experiences scale (Dissociative Experiences Scale, DES);
• Do not present psychological distress (score less than 8 on the Kessler Abbreviated Psychological Distress Scale, K6) ;
• Have a drug or alcohol dependence;
• Benefit from ongoing psychotherapeutic monitoring;
• Have already benefited from psychotherapeutic follow-up or have participated in studies in the last 6 months, both involving EMDR therapy.