Sensation, Perception, Attention and States of Consciousness
Sensation versus perception
Sensation is detection of physical energy by sense organs; perception is interpretation. Know absolute threshold (minimum detectable stimulus), difference threshold (just noticeable difference, Weber's law), and signal detection theory (hits, misses, false alarms, correct rejections, influenced by sensitivity and criterion). Sensory adaptation reduces response to constant stimulation.
Perceptual organisation
Gestalt principles include proximity, similarity, continuity, closure, and figure-ground. Depth cues are binocular (retinal disparity, convergence) and monocular (linear perspective, relative size, interposition, texture gradient, motion parallax). Perceptual constancies (size, shape, brightness) maintain stability. Top-down processing uses expectations; bottom-up uses raw features. Illusions reveal how these mechanisms misapply.
Attention
Attention is selective, divided, and sustained. Cocktail-party effect illustrates selective auditory attention; inattentional blindness and change blindness show limits. Automatic versus controlled processing differ in effort and capacity.
States of consciousness
Normal waking, daydreaming, sleep stages (NREM stages, REM with dreaming and muscle atonia), and altered states (hypnosis, meditation, drugs). Sleep theories include restoration and consolidation. Drug categories: depressants, stimulants, hallucinogens.
Traps and rule of thumb
Questions often confuse sensation with perception, or label convergence as monocular. Rule of thumb: cues needing two eyes are binocular; everything else is monocular. Remember Weber's law concerns proportional, not absolute, change.