Background: As streaming platforms face intensifying competition, understanding how cognitive biases shape purchasing choices presents both a theoretical gap and a practical opportunity. While the Decoy Effect and the Von Restorff Effect have been independently studied in marketing, their potential combined influence on consumer behavior remains under explored.

Purpose: This thesis aims to investigate the individual and combined effects of the Decoy Effect and the Von Restorff Effect on consumer purchase decisions in the streaming services industry. By integrating the Theory of Planned Behavior, the study seeks to uncover how these cognitive biases influence not only consumer choices but also the behavioral intentions underlying those decisions.

Method: A quantitative experimental design was employed involving 162 participants randomly assigned to one of four groups: Control, Decoy Effect, Von Restorff Effect, or a Combination of both. Participants evaluated simulated subscription plans from a fictional streaming platform. Their plan preferences were measured alongside attitudes, subjective norms, and perceived behavioral control using a TPB based survey. Data was analyzed using ANOVA and multiple regression techniques to assess both group differences and psychological predictors.

Conclusion: The results indicate that the combination of the Decoy Effect and the Von Restorff Effect significantly increases the likelihood of consumers selecting a premium plan, compared to either bias alone or the control group. Attitudes emerged as the strongest predictor of purchase intention within the TPB framework and were directly increased by cognitive biases. These findings suggest actionable implications for marketers and developed academic understanding of cognitive biases connection. Future research should examine these effects across broader demographics and real-world platforms.