<p dir="ltr">This study investigates healthcare decision-making dynamics among adults diagnosed with autism spectrum disorder (ASD) without intellectual disability (ID), focusing on the influence of the egocentric norm concept and comparing it to neurotypical (NT) individuals. Employing a quasi-experimental design and meticulously developed vignettes, the research gathers quantitative and qualitative data from Prolific survey responses, exploring nuances in decision processes. The findings reveal substantial disparities in response patterns between individuals with ASD without ID and NT counterparts, emphasizing the significance of the egocentric norm. Factor analysis and structural equation modeling support the validity of the questions and highlight egocentric norms’ impactful role in health-related decisions.</p><p dir="ltr">Qualitatively, themes within both groups illuminate unique decision-making processes, including enduring support from significant others, autonomy trends, and reliance on digital resources. The study contributes nuanced insights for healthcare practitioners, policymakers, and educators, emphasizing the need for tailored interventions that resonate with the distinctive decision-making dynamics of individuals with ASD without ID. While acknowledging limitations related to sample characteristics and reliance on self-reported data, the study provides an in-depth understanding of the interplay between the egocentric norm, Reasoned Action Approach (RAA) concepts, and other influential factors in healthcare decision-making.</p>