Accepted for/Published in: JMIR Serious Games
Date Submitted: May 5, 2025
Date Accepted: Nov 10, 2025
Shadow-Induced Forgetting in a Game-Based Paradigm on Non-Clinical Adults: Crossover Study on the Effects of Consciousness, Emotional Valence, and Temporal Dynamics
ABSTRACT
Background:
Managing intrusive thoughts is a fundamental cognitive function, and intentional forgetting plays a crucial role in mental well-being. Shadow-induced Forgetting (ShIF) is a phenomenon where unrelated episodic memories are weakened when presented during an amnesic shadow—a brief temporal window proximal to suppression tasks.
Objective:
To examine how ShIF varies based on image exposure conditions (conscious vs. unconscious), emotional valence (positive vs. negative), and temporal dynamics (short- vs. long-term effects).
Methods:
This single-center, within-subjects experimental study enrolled 66 university students aged 19-29 years between December 1, 2023 and March 1, 2024. Participants learned cue-target associations while controlling a character in a motor task. We designed a novel game-based paradigm where habitual motor responses were disrupted by reversing game controls, thereby inducing an amnesic shadow. Memory performance was assessed using METEOR scores (semantic similarity measure) immediately after intervention (Day 1), at 24 hours (Day 2), and at 72 hours (Day 4). Electroencephalography (EEG) was conducted on 40 participants to validate neural mechanisms underlying memory suppression.
Results:
A total of 56 participants completed all assessments, with 10 excluded due to technical issues or incomplete data. Significant short-term ShIF effects were observed for consciously cued negative images, characterized by reduced memory performance immediately after the intervention. EEG analyses revealed elevated inhibitory neural activity during suppression of negative memories. Over time, the ShIF effect for consciously cued images diminished, whereas a delayed effect emerged for unconsciously cued images.
Conclusions:
ShIF is more effective for negative and consciously accessed memories, underscoring the efficacy of game-based interventions in facilitating intentional forgetting. These findings have potential applications in developing interventions to alleviate distressing memories, such as those experienced in posttraumatic stress and obsessive-compulsive disorders. Clinical Trial: CRIS Register Number: KCT0009516; https://cris.nih.go.kr/cris/search/detailSearch.do?seq=29053&search_page=L
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