A well-known phenomenon called perceptual learning is widely accepted as good evidence that perception in general can indeed be modified. Perceptual learning refers to improvement in a given perceptual skill through repeated practice. For example, as a result of practice, people get better at discriminating between very slightly different line orientations, detecting tiny gaps between two offset lines (vernier acuity), and detecting very low-contrast patterns. Through practice, people can improve their performance on just about any perceptual task you can think of. Evidence suggests that this learning takes place at the earliest (most fundamental) stages of visual processing, in the brain area referred to as the primary visual cortex. Research in neuroscience and psychophysics shows that the brain is a plastic, adaptive organ that is ever changing to meet the demands of the environment.