 One of the main reasons for holding that improvements in perceptual discrimination can be genuinely perceptual is due to somewhat recent evidence from neuroscience. As Manfred Fahle puts it, during the 1970s and 1980s, it tended to be the case that improvements in perceptual discrimination were thought to be cognitive rather than perceptual (2002: xii). However, during the 1990s, pressure was put on the cognitive interpretation due to new neuroscientific evidence in perceptual learning studies. In particular, studies found that learning-induced plasticity occurs in the adult primary sensory cortices much more than researchers had previously thought (Fahle 2002: xii). Neurological evidence of plasticity in adult primary sensory cortices due to learning provides some evidence that changes in perceptual discrimination can be due to perceptual learning. (See also Garraghty &amp; Kass 1992: 522; Gilbert 1996: 269; Goldstone 2003: 238; Gilbert &amp; Li 2012: 250; and Sagi 2011: 1552–53).