Model Human Processor

A cognitive architecture developed by Card, Moran, and Newell (1983) that models human information processing as three interconnected subsystems: perceptual, cognitive, and motor processors, each with characteristic cycle times. The perceptual processor (~100ms) handles sensory input, the cognitive processor (~70ms) performs decision-making, and the motor processor (~70ms) executes physical actions. The model predicts that simple reaction time equals the sum of these cycles (approximately 240-270ms for able-bodied users). In accessibility research, MHP helps explain and predict switch access performance, as users with motor disabilities show extended motor cycle times (100-300ms) while perceptual and cognitive times remain typical.