The SIGCSE Technical Symposium is celebrating its 50th year, and a constant theme throughout this history has been to better understand how novices learn to program. In this paper, we present a perspective on the evolution of introductory programming education research at the Symposium over these 50 years. We also situate the Symposium's impact in the context of the wider literature on introductory programming research. Applying a systematic approach to collecting papers presented at the Symposium that focus on novice programming / CS1, we categorized hundreds of papers according to their main focus, revealing important introductory programming topics and their trends from 1970 to 2018. Some of these topics have faded from prominence and are less relevant today while others, including many topics focused on students, such as making learning programming more appropriate from gender, diversity, accessibility and inclusion standpoints, have garnered significant attention more recently. We present discussions on these trends and in doing so, we provide a checkpoint for introductory programming research. This may provide insights for future research on how we teach novices and how they learn to program.