Exploring the Role of Working Memory Saturation in Eye Movement Desensitization and Reprocessing (EMDR) Using the Eye Blink Conditioning Paradigm

NCT06878807 | Completed

• 1 other identifier: HCB/2021/0283
• Study Type: interventional
• Target: 112
• Locations: 1 country
• Sites: 1

Brief Summary

Eye Movement Desensitization and Reprocessing (EMDR) is a well-established, evidence-based treatment for posttraumatic stress disorder (PTSD). It is endorsed by leading organizations such as the American Psychiatric Association and the World Health Organization. During EMDR therapy, patients focus on recalling traumatic events while simultaneously engaging with an external stimulus. Specifically, patients undergo lateral eye movements. This process is believed to reduce the vividness and emotional intensity of traumatic memories by addressing and desensitizing their cognitive, emotional, and physical components. Despite its proven efficacy in treating PTSD, the precise mechanisms underlying these therapeutic effects remain not fully understood. Several hypotheses have been proposed to explain the efficacy of EMDR. Among them, the working memory hypothesis is particularly influential and is supported by a substantial body of research. This hypothesis suggests that aversive memories and fear, when recalled, occupy limited memory resources. Therefore, performing a task, such as eye movements, during the recall of the traumatic experience would result in a competition for limited memory resources, leading to a decrease in the vividness and emotional intensity of the traumatic memory. Consequently, the dual task inherent in EMDR is thought to facilitate a rapid elimination of the emotional responses triggered by the traumatic memory, allowing patients to alleviate the physical and psychological distress associated with the trauma. Measuring the effects of an EM intervention through a standardized protocol could clarify the conditions under which the intervention is most effective and elucidate the potential mechanisms of EMDR. In this context, the Eye Blink Conditioning (EBC) task, a well-established and standardized conditioning paradigm, seems relevant for testing the working memory hypothesis. In the EBC task, eyelid closure is measured in response to a corneal air puff, which acts as the unconditioned stimulus. The unconditioned stimulus is paired with a neutral stimulus, a tone, which becomes a conditioned stimulus by eliciting a conditioned response similar to that produced by the unconditioned stimulus. After the conditioning phase, participants undergo the extinction phase. In this phase, the conditioned stimulus is presented without the unconditioned stimulus for many trials, and the main objective is to measure how many trials it takes for the participants to eliminate the previous associative learning between the aversive stimulus (air puff) and the conditioned stimulus (tone). This study aimed to explore whether the effectiveness of a straightforward eye movement intervention in accelerating extinction is influenced by the working memory hypothesis. The hypothesis is that the enhancement of extinction learning is dependent on working memory saturation. Understanding the role of working memory saturation in the effectiveness of eye movements during extinction learning could provide critical insights into the working memory hypothesis as a potential key mechanism underlying the efficacy of EMDR therapy.

Conditions

Eye Movement Desensitization and Reprocessing

Outcome Measures

Primary Outcomes (1)

• Extinction Learning Differences

  Assesses the number of conditioned responses (CR) during the initial block of the extinction phase.

  Baseline

Secondary Outcomes (4)

• Latency of Eyeblink Conditioned Response (CR) During the Eye Blink Conditioning Task

  Baseline

• Intensity of Eyelid Closure During the Eye Blink Conditioning Task

  Baseline

• Trauma History (Childhood Trauma Questionnaire)

  Baseline

• Trauma History (Life Events Checklist-5)

  Baseline

Study Arms (3)

Eye Movement Intervention

EXPERIMENTAL

Participants underwent EM tasks during the first 30 seconds of the extinction phase. All participants in this group experienced identical EM conditions in terms of speed and duration

Behavioral: eye movement

TMT-B

ACTIVE COMPARATOR

Participants performed the Trail Making Test B (TMT-B).

Behavioral: TMT-B

Control group

NO INTERVENTION

Participants engaged in no additional task. These subjects were told to focus their gaze on a wall in front of them.

Interventions

eye movement BEHAVIORAL

Participants underwent EM tasks during the first 30 seconds of the extinction phase. All participants in this group experienced identical EM conditions in terms of speed and duration.

Eye Movement Intervention

TMT-B BEHAVIORAL

Participants performed the Trail Making Test B (TMT-B).

TMT-B

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age between 18 and 65 years
• Provide informed consent

You may not qualify if:

• Prior exposure to EMDR therapy or eye movement (EM) experiments
• Positive diagnosis of PTSD or other Axis I disorders as determined by the Mini-International Neuropsychiatric Interview (MINI)
• Hearing or visual impairments

Sponsors & Collaborators

• Hospital Clinic of Barcelona: lead

Study Sites (1)

Hospital Clinic de Barcelona

Barcelona, Barcelona, Spain

Location

MeSH Terms

Interventions

Eye Movements

Intervention Hierarchy (Ancestors)

Movement; Musculoskeletal Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena; Ocular Physiological Phenomena

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Interim Junior Group Leader

Study Record Dates

• First Submitted: February 6, 2025
• First Posted: March 17, 2025
• Study Start: April 1, 2022
• Primary Completion: December 1, 2024
• Study Completion: April 1, 2025
• Last Updated: September 16, 2025

Record last verified: 2025-09

Data Sharing

• IPD Sharing: Will not share

Locations

ES (1)