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Ali Hashemi, Matthew Pachai, Allison Sekuler, Patrick Bennett; Learning to generalize stimulus-specific learning across contexts. Journal of Vision 2016;16(12):1110. doi: 10.1167/16.12.1110.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual learning (PL) in a texture identification task occurs because observers become more sensitive to diagnostic stimulus components, but the particular components that are learned vary across observers. Here, we encouraged observers to adopt a specific processing strategy by manipulating the diagnostic orientation structure of textures. Six targets were generated by applying a 0±30 deg orientation-filter to band-pass filtered white noise. Targets were embedded in non-diagnostic contexts created by filtering novel textures with a 90±30 deg orientation band. The remaining empty orientations served as potential cues for distinguishing the target and context. In a 1-of-6 identification task, observers were trained with the horizontal Target alone (hT-only) or in a vertical Context (hT+vC). Before and after training, observers were tested with hT-only and hT+vC stimuli and controls (vT-only and vT+hC). Training with hT-only produced strong stimulus- and context-specific learning; hT+vC training led to weak but stimulus-specific and context-generalizable learning. Next, we examined if context-generalization reflected a broader, stimulus-transferable learning by testing hT+vC trained observers with novel hT textures. Again, learning was minimal: almost half of the observers did not exhibit learning. For those who learned, we found no evidence of context-generalization or stimulus-transfer. Finally, to make it easier to distinguish targets and context during training, target contrast was held constant while context contrast was varied with a 1up/1down staircase. Significant learning occurred: across training blocks, observers tolerated increasingly higher levels of context contrast. Unlike previous experiments, training improved performance for both the same hT+vC and hT-only stimuli; however, training did not affect performance with novel hT or vT stimuli. Thus, learning was context-generalizable but not stimulus-transferable. In conclusion, learning to identify structure in a specific orientation is difficult when that information is embedded in non-informative orientation information, but this difficulty can be overcome by providing cues to distinguish components.
Meeting abstract presented at VSS 2016
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