The ubiquitous presence of smartphones has transformed the way humans interact with technology and has significantly influenced various aspects of modern life. While smartphones provide immense convenience and access to information, concerns have emerged regarding their potential negative impact on cognitive abilities. This research paper critically reviews the existing literature on how smartphone use may be associated with declining intelligence and cognitive performance. The paper examines various studies, experiments, and surveys conducted over the years, presenting the current state of knowledge on this topic. Additionally, it explores potential mechanisms through which excessive smartphone usage might affect cognitive functioning and suggests areas for future research.