Chromatic Perceptual Learning but No Category Effects without Linguistic Input

Abstract

Perceptual learning involves an improvement in perceptual judgment with practice, which is often specific to stimulus or task factors. Perceptual learning has been shown on a range of visual tasks but very little research has explored chromatic perceptual learning. Here, we use two low level perceptual threshold tasks and a supra-threshold target detection task to assess chromatic perceptual learning and category effects. Experiment 1 investigates whether chromatic thresholds reduce as a result of training and at what level of analysis learning effects occur. Experiment 2 explores the effect of category training on chromatic thresholds, whether training of this nature is category specific and whether it can induce categorical responding. Experiment 3 investigates the effect of category training on a higher level, lateralized target detection task, previously found to be sensitive to category effects. The findings indicate that performance on a perceptual threshold task improves following training but improvements do not transfer across retinal location or hue. Therefore, chromatic perceptual learning is category specific and can occur at relatively early stages of visual analysis. Additionally, category training does not induce category effects on a low level perceptual threshold task, as indicated by comparable discrimination thresholds at the newly learned hue boundary and adjacent test points. However, category training does induce emerging category effects on a supra-threshold target detection task. Whilst chromatic perceptual learning is possible, learnt category effects appear to be a product of left hemisphere processing, and may require the input of higher level linguistic coding processes in order to manifest.

Effects of Language on Visual Perception

“…Second, are studies showing that color discrimination can be altered within an individual by manipulating linguistic factors. Learning new color categories (analogous in some ways to children learning to produce and comprehend color labels) can induce more categorical color perception [52][53][54] a finding consistent with both off-line and on-line effects of language ( Fig. 2a).…”

“…The predictive coding perspective may help to make sense of the limits on the effects of language on perception and the often-observed task sensitivity. For example, people who speak languages with different color naming schemes do not appear to differ in how small a color difference they are able to perceive (i.e., size of their just-noticeable difference) [54,92]. Within a language too, the size of a just-noticeable-difference is not well correlated with the placement of lexicalized color categories [93]; and categorical color perception itself is surprisingly task-dependent [94,95].…”

Misconceptions About Colour Categories

“…This may explain why many of the effects observed in previous studies disappeared when using different stimulus samples (Bachy, Dias, Alleysson, & Bonnardel, 2012;A. M. Brown, Lindsey, & Guckes, 2011;Cropper, Kvansakul, & Little, 2013;Davidoff, Goldstein, Tharp, Wakui, & Fagot, 2012;Gerhardstein, Renner, & Rovee-Collier, 1999;Grandison et al, 2016;Lindsey et al, 2010;Roberson, Hanley, & Pak, 2009;M. A. Webster & Kay, 2012;Witzel, Cinotti, & O'Regan, 2015;Witzel & Gegenfurtner, 2011.…”

“…They found that colour vision itself is inherently categorical (Regier, Kay, & Khetarpal, 2007), and that colour categories already exist in infancy before language acquisition (Bornstein, Kessen, & Weiskopf, 1976;Franklin, Clifford, Williamson, & Davies, 2005;Franklin & Davies, 2004;Franklin, Drivonikou, Bevis, et al, 2008;Franklin, Drivonikou, Clifford, et al, 2008;Franklin, Pilling, & Davies, 2005;Ozturk, Shayan, Liszkowski, & Majid, 2013;Skelton, Catchpole, Abbott, Bosten, & Franklin, 2017). Still other findings did not find categorical patterns in colour perception and contradicted the idea of categorical perception (Bachy et al, 2012; A. M. Brown, Lindsey, & Guckes, 2011;Cropper, Kvansakul, & Little, 2013;Davidoff, Goldstein, Tharp, Wakui, & Fagot, 2012;Gerhardstein, Renner, & Rovee-Collier, 1999;Grandison et al, 2016;Kay & Kempton, 1984; Misconceptions about colour categories 8 al., 2010; Roberson, Hanley, & Pak, 2009;Webster & Kay, 2012;Witzel & Gegenfurtner, 2011. How is it possible that some studies observe effects of categories on perception, other studies find that perception determines categories, and still others do not find any evidence for categorical perception?…”

Red is the new orange: Nonlinguistic categorical color perception

“…Bgreen^(yeondu, or yellow-green, and chorok, or green) find these two colors to be more dissimilar than do English speakers (reviewed by Davidoff & Fagot, 2010). Although the extent to which language affects color categorization remains a matter of debate, it is generally accepted that linguistic labels have a unique and profound effect on our perception and categorization of colors (e.g., Grandison et al, 2016).…”