Infant long-term memory: The last quarter century and the next.

Over the last quarter century, research on infant long-term memory has explored the complex, nuanced ways infants remember and how early memories shape interactions with the world. Pioneering investigations in the 1950s and 1960s revolutionized the study of infant cognition and memory. By 2000, foundational properties of infant memory were established via preferential looking, imitation, and operant conditioning paradigms. In the years since, research has advanced understanding of how infants encode, consolidate, and retrieve information across diverse situations. This body of work has revealed that infants possess memory capacities once thought to emerge later in development and that experience shapes both the duration and flexibility of memory. Systematic investigations of reminders have established the necessary and sufficient conditions for retrieval, emphasizing the roles of context, cue, and timing. Advances in behavioral and neuroimaging research, including sleep-based paradigms, have provided insights into memory consolidation during infancy. Recent studies have also broadened the scope of inquiry to include early learning and retention across various media, such as picture books, television, and touchscreens. However, debate continues regarding the nature of infant memory and whether different types of memory follow distinct developmental trajectories. This review outlines future research directions, including how intertwined learning, memory, and attention processes influence one another and are shaped by the dynamic and evolving niches that infants inhabit. Despite major progress, important questions remain unresolved, including the characterization and fate of our earliest memories.