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

NCT ID: NCT06878807

Last Updated: 2025-09-16

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 112 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2022-04-01
• Study Completion Date: 2025-04-01

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

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: SINGLE

Study Groups

Eye Movement Intervention

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

Group Type: EXPERIMENTAL

eye movement

Intervention Type: 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.

TMT-B

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

Group Type: ACTIVE_COMPARATOR

TMT-B

Intervention Type: BEHAVIORAL

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

Control group

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

Group Type: NO_INTERVENTION

No interventions assigned to this group

Interventions

eye movement

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.

Intervention Type: BEHAVIORAL

TMT-B

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

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

• Age between 18 and 65 years
• Provide informed consent

Exclusion Criteria

• 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

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 65 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Hospital Clinic of Barcelona

OTHER

Sponsor Role: lead

Responsible Party

Hugo López-Pelayo

Interim Junior Group Leader

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

Hospital Clinic de Barcelona

Barcelona, Barcelona, Spain

Countries

Spain

Other Identifiers

HCB/2021/0283

Identifier Type: -

Identifier Source: org_study_id