Abstract
The neural correlates of visual statistical learning (VSL) remain debated, but neuroimaging and neuropsychological findings support the emerging view that MTL involvement is needed for this form of implicit learning. We extended new findings showing that performance on classic triplet VSL tasks is interrupted in amnesic patients. We sought to test whether some forms of VSL may persist without intact MTL, by combining stimuli within and between broad categories (faces and scenes) in an otherwise typical VSL paradigm. In Experiment 1, the familiarization task required participants to monitor sequentially presented faces (male/female) and scenes (indoor/outdoor), and to report image flickers. 16 AB pairs were repeated, such that A always predicted B. The nature of these pairs was the key manipulation. To examine how categorical boundaries impact VSL these pairs were consistent (male->male; indoor->indoor), inconsistent (male->female; indoor->outdoor) or cross-category (male->outdoor; indoor->female). During a surprise 2AFC recognition phase, the task was to pick the more familiar pairing versus a foil. Here, the amnesic participant showed chance performance, suggesting no VSL and a reliance of this form of VSL on MTL structures. In Experiment 2, the familiarization task was modified to require a stimulus categorization judgment. During the recognition stage, the patient demonstrated significantly above chance performance for a subset of AB pairs. Surprisingly, her recognition was better for the pairs that crossed category boundaries, regardless of whether the same (male ->outdoor) or a different (male->indoor) motor response was required. She showed this same pattern across two testing sessions separated by more than a week. These data provide additional context to our understanding of the relationship between VSL and the MTL. We found evidence of limited VSL despite profound MTL damage, suggesting that the neural underpinnings of VSL may be more varied and contingent on task demands than previously thought.
Meeting abstract presented at VSS 2017