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Sarit Szpiro, Laura Wang, Marisa Carrasco; Training reveals a coupling between overestimation and improved discrimination. Journal of Vision 2015;15(12):1299. doi: 10.1167/15.12.1299.
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© ARVO (1962-2015); The Authors (2016-present)
Goal. Training improves visual discrimination and detection (perceptual learning). Recently, we found that training on an estimation task leads to increased overestimation of motion directions from a boundary (Szpiro, Spering&Carrasco, Perceptual learning modifies untrained pursuit eye movements. Journal of Vision, 2014). Thus, two different training protocols (discrimination vs. estimation training) with similar motion direction stimuli can lead to seemingly different findings – improved discrimination versus increased overestimation. Can these results be linked? To examine whether and how these two perceptual phenomena are related – we assess the two training protocols with both tasks, for trained and untrained directions. Methods. For each observer, we determined discrimination coherence thresholds for ±4° motion directions from the horizontal via staircases and used it for training and testing. Two separate groups of observers trained on the ±4° with either an estimation (n=7), or a discrimination task (n=7); a third control group did not train (n=7). Training lasted three days. During pre and post-test, all observers were tested on the two tasks: a binary motion direction discrimination (up vs. down) and an analog direction estimation task by rotating a mouse. During testing we presented directions of ±2°(difficult), ±4° (trained) and ±8° (easy). No feedback was given during the experiment. Results and Conclusion. Neither estimation nor discrimination accuracy changed in the control group. In contrast, training on estimation significantly increased overestimation and improved discrimination for trained and untrained directions. Similarly, training on discrimination significantly improved discrimination accuracy and increased overestimation for trained direction and untrained-easy directions. Thus, we found coupling between two different tasks, with different goals (categorization vs. estimation): improved discrimination was paired with increased overestimation and vice versa. These results suggest that improvements in perceptual tasks due to training may stem from a shift in the perceived stimuli, possibly in order to improve categorization.
Meeting abstract presented at VSS 2015
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