Is Seeing Believing? Exploring the McGurk Effect

Overview

The McGurk effect demonstrates audiovisual integration in speech perception: when auditory and visual syllables conflict (e.g., auditory /ba/ paired with visual /ga/), listeners often report a fused percept such as /da/). Although this effect is well established in adults, it remains unclear at what age children integrate auditory and visual speech information automatically. My study investigated whether susceptibility to the McGurk effect differs between 4-year-olds, 11-year-olds, and adults (N=15). Participants completed six incongruent audiovisual trials under eyes-closed and eyes-open conditions and reported what they heard. Fusion responses, reports of a third syllable different from both the auditory and visual inputs, served as the primary measure of audiovisual integration. In the eyes-closed condition, fusion responses were minimal across all groups, confirming that visual input was necessary to elicit the effect. In the eyes-open condition, participants were more likely to report fused sounds when visual information conflicted with auditory information. Developmental differences emerged: four-year-olds produced very few fusion responses (7%), indicating they were less likely to be McGurked and suggesting that automatic audiovisual integration is still developing. In contrast, 11-year-olds (43%) showed fusion rates comparable to adults (40%), demonstrating adult-like integration by late childhood. Fusion rates also varied by stimulus: sounds with more visible mouth movements (e.g., /ba/, /va/) elicited higher fusion overall (e.g., “ba-ga” 37%; “ba-va” 30%), suggesting that more visually prominent articulations are more likely to be integrated with auditory input. Together, my findings highlight developmental strengthening of audiovisual speech integration and the role of visual prominence in shaping perception.

Competition history

• CSEF 2026 Behavioral & Social Sciences (Junior Division) · Entry J-03-08

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