This study examines the joint effects of interactivity, task complexity, and product knowledge on customers' online purchase decision quality. Interactivity is defined as the extent to which users can participate in modifying the form and content of a mediated environment in real-time. For example, users sort products on a website based on certain criteria (e.g., price). An experiment with 264 participants was conducted to test the hypotheses. The results suggest that interactivity and task complexity jointly affect customers' online purchase decision quality. When customers perform a complex task, interactivity reduces the cognitive resources needed to perform the task and thus improves customers' decision quality. However, when customers perform a simple task, interactivity worsens the mismatch between the cognitive resources available and what is required, leading to deteriorated decision quality. Similarly, product knowledge and task complexity interact to influence customers' decision quality. Product knowledge improves decision quality when customers perform a complex task, whereas it results in deteriorated decision quality when customers perform a simple task. In addition, interactivity interacts with product knowledge to affect customers' intention to revisit the website. Specifically, interactivity has a stronger effect on customers' intention to revisit the website when the customer has more product knowledge.
