Multiple Sequence Learning Systems

Schmidt, Kevin

doi:https://doi.org/10.21985/n2-nc2s-zw87

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Multiple Sequence Learning Systems

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Much prior research on memory systems has focused on establishing dissociations between different types of memory based on behavior, subjective experience, and the brain: explicit memory depends on the medial temporal lobe and is thought to operate consciously through a relatively slower processing bottleneck, while implicit memory is a term for all other learning operating outside subjective awareness and not dependent on the medial temporal lobe. However, to account for findings such as implicit-like statistical effects on medial temporal lobe dependent explicit memories, research must refocus on the interaction between multiple memory systems. This idea was tested in several experiments that assessed how statistical information can be imposed on a nominally explicit recognition memory task. A novel high-repetitions recognition memory task was developed with rapid decision making and feedback over hundreds of lists of kaleidoscope images and perceptually similar foil images. After practice with a consistently ordered sequence of images, an advantage developed for detecting items in a practiced sequence compared to shuffled items. Participants developed greater detection sensitivity (d’) for sequences of practiced items, while shuffling the list items shifted participants into a more liberal decision criterion (c). Data demonstrated that this reduced this statistical learning fluency effect in processing developed early in training and was stable across days. Participant subjective reporting revealed an explicit conscious awareness of the performance gain in sequence, and speed and flexibility operating characteristics further suggested an interaction of multiple memory systems. The data presented suggest reconceptualization of the strict anatomical and subjective distinctions between memory systems to allow implicit statistical learning mechanisms to operate on explicit memory structures.

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