Categories at the middle level are perceptually and conceptually the more salient. This is perceptually indistinguishable from septimal meantone temperament. Martinet predicted that perceptually similar pairs of phonemes with low functional load would merge. Motion is intrinsically indeterminate, but perceptually determinable, with respect to its length. CIELAB produces a color space that is more perceptually linear than other color spaces. Children extended labels to two perceptually similar animals more often than when they were dissimilar. It is perceptually pleasing to divide objects into an even number of symmetrical parts. Augmented reality is used to enhance natural environments or situations and offer perceptually enriched experiences. The Munsell value has long been used as a perceptually uniform lightness scale. Richard Serra's huge, rusty steel works, which also invite viewers into perceptually confounding interiors. His subjects restored the missing speech sound perceptually without any difficulty. Diagnosis, up until today, is generally purely perceptually based. Perceptually uniform color spaces outperform RGB in cases such as high noise environments. He attributes this to either "maturation" (perceptually) or "experience".