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Gong-Liang Zhang, Cong Yu; Properties of exposure-based motion direction learning. Journal of Vision 2016;16(12):547. doi: 10.1167/16.12.547.
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Although most perceptual learning studies focus on task-relevant learning, task-irrelevant exposure-based learning (EBL) also occurs as a result of observers' mere exposure to a stimulus feature (Watanabe et al. 2001, Gutnisky et al. 2009). Here we investigated properties of EBL of motion direction discrimination. Observers were passively exposed to random dot kinematogram (RDK) for 5 daily sessions. Before and after exposure, a staircase procedure was used to estimate motion direction discrimination thresholds. We found that (1) After the observers were exposed to subthreshold RDK(coherence = 10%) or null-coherence RDK (coherence = 0) while only performing an irrelevant luminance discrimination task in catch trials (20%), motion direction thresholds were improved significantly at the exposed direction by 41.9 ± 7.0% (p< 0.001) and an unexposed orthogonal direction by 35.3 ± 8.1% (p< 0.001), or at any direction by 35.8 ± 3.2% (p< 0.001) when coherence = 0. (2) The EBL required a pretest of the motion direction discrimination task. Otherwise the improvement was substantially reduced and insignificant (10.0 ± 7.4%, p= 0.21). (3) When the subthreshold RDK (coherence = 10%) was paired with an irrelevant luminance discrimination task every trial with feedback, significant reduction of direction discrimination thresholds was evident only at the exposed direction (31.0 ± 4.1%, p < 0.001), but not at an orthogonal direction (7.3 ± 3.7%, p = 0.10). (4) When attention was distracted from RDK (coherence = 0%) by a central RSVP task, no significant threshold changes were observed (8.7 ± 6.3%, p= 0.24). These results indicate that the interaction between pretest task priming and stimulus exposure, as well as attention to exposed stimulus, are essential for EBL to occur. Reinforcement signals are not required for EBL, but they may gate EBL by limiting EBL to directions that are temporally associated with the reinforcements.
Meeting abstract presented at VSS 2016
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