Perceptual fluency is the ease of processing stimuli based on manipulations to perceptual quality. Perceptual grouping is the process that determines what these "pieces" of the perceptual field are. Hallucinogens cause perceptual and cognitive distortions without delirium. Categorical perception is involved in processes of perceptual differentiation. Psychiatry focuses on affective, behavioral, cognitive, and perceptual disorders. The disorder is typically associated with cognitive disruptions in early perceptual and attentional processes. Psychological tests measure specific abilities, such as clerical, perceptual, numerical, or spatial aptitude. This law describes a relation between visual input and mental perceptual states. Another conceptualization classified attention into mental attention and perceptual attention. Color theory has described perceptual and psychological effects to this contrast. Philosophies of mind explore whether objectivity relies on perceptual constancy. Operating the LCAC demands unique perceptual and psychomotor skills. Multimodality integrates different senses into one unified perceptual experience. Like perfect pitch, synesthesia is simply a difference in perceptual experience. As a rule, they underestimate maladaptiveness of their social isolation and perceptual distortions.