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Andreas Marzoll, Takeo Watanabe; Task-irrelevant perceptual learning of moving natural stimuli induces a bias away from the exposed movement direction. Journal of Vision 2021;21(9):2164. doi: https://doi.org/10.1167/jov.21.9.2164.
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© ARVO (1962-2015); The Authors (2016-present)
Although visual research often employs artificial stimuli, real visual systems are highly tuned to the properties of naturalistic stimuli (Rao & Ballard, 1999). It has been found that task-irrelevant perceptual learning (TIPL) of suprathreshold stimuli does not occur because of inhibition to the stimuli (Tsushima, Sasaki & Watanabe, 2006). At the same time, it has been reported that no or less attention is necessary for a task-irrelevant naturalistic stimulus to be proceeded (Li et al., 2002). In the present study, we investigated if suprathreshold naturalistic stimuli can circumvent attentional inhibition in TIPL. Six subjects received ten sessions of exposure to moving natural scenes. In each trial (8000 total), subjects completed a central RSVP task while a surrounding natural image moved in a constant direction for each subject (direction randomized between subjects). Before and after exposure, subjects completed a dot motion discrimination task in which they were instructed to identify the direction of 5% or 10% coherently moving dots from among seven equidistant directions (560 trials). Accuracy in the RSVP task increased from 63% to 79% across sessions. Unlike other TIPL studies, motion discrimination accuracy for the exposed direction decreased by about 25%, while an increase of 5% was found for the other directions. Closer investigation revealed that this change was due to a change in response behavior. Given any veridical direction, responses toward the exposed direction decreased by 16%, but increased to the two directions most distant from it (±154°) by 17%. The two intermediate directions did not change noticeably on average (-2% for ±51° and +3% for ±103°). These results suggest a disruptive effect for the exposed direction on TIPL of the direction if the moving backgrounds are natural scenes or, alternatively, a facilitatory effect of the possible head motion direction (as opposed to the low-level pixel movement direction).
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