Statistical learning as a reference point for memory distortions: Swap and shift errors.

Humans use regularities in the environment to facilitate learning, often without awareness or intent. How might such regularities distort long-term memory? Here, participants studied and reported the colors of objects in a long-term memory paradigm, uninformed that certain colors were sampled more frequently overall. When participants misreported an object's color, these errors were often centered around the average studied color (i.e., "Rich" color), demonstrating swap errors in long-term memory due to imposed statistical regularities. We observed such swap errors regardless of memory load, explicit knowledge, or the distance in color space between the correct color of the tested object and the Rich color. An explicit guessing strategy where participants intentionally made swap errors when uncertain could not fully account for our results. We discuss other potential sources of observed swap errors such as false memory and implicit biased guessing. Although less robust than swap errors, evidence was also observed for subtle shift errors towards or away from the Rich color dependent on the color distance between the correct color and the Rich color. Together, these findings of swap and shift errors provide converging evidence for memory distortion mechanisms induced by a reference point, bridging a gap in the literature between how attention to regularities similarly influences visual working memory and visual long-term memory.