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Ying-Zi Xiong, Jun-Yun Zhang, Cong Yu; Under-stimulation at untrained orientation may explain orientation specificity in perceptual learning. Journal of Vision 2015;15(12):38. doi: 10.1167/15.12.38.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual learning (PL) can transfer completely to an orthogonal orientation if the latter is exposed through an irrelevant task in a Training-plus-Exposure (TPE) paradigm (Zhang et al., 2010). This and additional evidence for learning transfer to new locations/hemisphere after double training (Xiao et al, 2008) suggests that PL reflects cognitive changes beyond the early visual areas. However, it is unclear why PL is orientation specific in the first place and why exposure to the transfer orientation enables learning transfer. Here we used a continuous flashing suppression paradigm to investigate the role of orientation exposure in TPE training. Foveal orientation discrimination was always trained at one orientation. In other blocks of trials flashing white noise was presented to one eye, which suppressed the awareness of an orthogonal Gabor (sometimes a letter C) presented to the other eye. In Experiment I, the observers reported the color (red/green) of a small dot centered on the flashing noise images. They were not told that an orthogonal Gabor was shown to the other eye. This bottom-up orientation exposure produced partial learning transfer to the orthogonal orientation. In Experiment II, the observers guessed whether a Gabor/C was presented, but the orthogonal Gabor was not shown. Such top-down only “orientation exposure” led to no learning transfer. In Experiment III when the orthogonal Gabor did show, learning transfer was complete with this combined bottom-up and top-down orientation exposure. These results indicate that bottom-up orientation exposure is required for learning transfer, and that orientation specificity may result from under-stimulation of untrained orientations, possibly because these orientations are unstimulated or even suppressed during training. Although top-down influence itself has no impact on learning transfer, it can boost the effect of bottom-up exposure, so that high-level learning can functionally connect to new orientation inputs for complete learning transfer.
Meeting abstract presented at VSS 2015
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