Glossary

Search results

Anticipatory Grasp(also: Pregrasp Planning, Pre-grasp, Pre-shaping)

Anticipatory grasp refers to the pre-shaping of the hand before contact with an object, based on expectations about the object's size, shape, and orientation. In sighted people this planning is driven primarily by visual input during the reach phase and produces smooth,…

Childhood apraxia of speech(also: CAS, Developmental verbal dyspraxia, DVD)

A motor speech disorder in which the brain has difficulty planning and coordinating the precise movements of the tongue, lips, jaw, and palate needed for intelligible speech. Unlike other speech disorders caused by muscle weakness, CAS involves impaired motor programming — the…

Co-contraction(also: Unintended Co-contraction, Muscle Co-activation)

The simultaneous activation of antagonistic muscles — for example, the biceps and triceps firing at the same time. Some co-contraction is normal and useful for joint stability, but involuntary or excessive co-contraction is common in conditions such as spasticity, cerebral…

Fractionation(also: Finger Fractionation, Finger Independence)

The ability to move individual fingers independently of one another, a key measure of fine motor control assessed in stroke rehabilitation. After a stroke, patients often lose fractionation, meaning that attempting to move one finger causes involuntary coupled movement in…

Grasp Aperture(also: Hand Aperture, Finger Aperture)

Grasp aperture is the distance between the thumb and opposing finger(s) as the hand opens to receive an object during a reach. It scales with perceived object size, peaks before contact at a value typically larger than the object itself, and then closes to grip - a well-studied…

Kinesthetics(also: Kinaesthetics, Kinesthesia, Kinesthetic sense)

The sense of body position, movement, and muscular effort derived from receptors in muscles, tendons, and joints. Kinesthetics is closely related to — and often used interchangeably with — proprioception, though kinesthesia typically emphasizes awareness of active movement while…

Mirror Neuron System(also: Mirror Neurons)

The mirror neuron system is a network of brain regions that activate both when a person performs an action and when they observe another person performing the same action. It is implicated in motor simulation, action understanding, and learning by imitation. Neuroscientific…

Motor Function Time(also: Motor Response Time, Motor Cycle Time)

The time required to execute a physical action such as pressing or releasing a key, clicking a mouse button, or moving a pointing device. In the Model Human Processor, motor function time for able-bodied users averages approximately 70 milliseconds per action. For motor-impaired…

Sensorimotor(also: Sensorimotor System, Sensorimotor Control)

Relating to the integration of sensory input (proprioception, vision, touch) with motor output (muscle activation and coordinated movement). Sensorimotor processes let people plan, execute, and correct movements in real time, usually without conscious effort. Neurological and…

Spasm(also: Muscle Spasm, Spasticity)

A sudden, involuntary contraction of a muscle or group of muscles that can cause uncontrolled movement or a temporary inability to move. Spasms are common in conditions such as cerebral palsy, spinal cord injury, and multiple sclerosis. In the context of computer accessibility,…

Submovement(also: Movement Component, Movement Segment)

A discrete component of a larger aimed movement, separated from other submovements by pauses or changes in velocity. According to the Optimized Submovement Model from motor performance theory, a rapid aimed movement such as moving a cursor to a target consists of an initial…

11 results.