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MACRO. A user-programmed set of input commands that can be executed as a single command.
MAIN MENU. The initial, or highest level, menu in a hierarchy.
MANUAL. (1) Operated by people rather than automatically. (2) Documentation giving instructions for the assembly, operation, or repair of a system or software application.
MASKING. Masking is the amount by which the threshold of audibility of a sound is raised by the presence of another (masking) sound. The unit customarily used is the decibel.
MEAN TIME BETWEEN FAILURE (MTBF). Availability formulation expressing the dependence of availability on reliability. Total system operating time divided by the number of system failures during that time period.
MEDIAL PLANE. The medial plane is a vertical plane that divides the body into left and right. It is perpendicular to the frontal plane.
MEMORY. (1) Recall and recognition of anything previously learned or experienced. (2) The component of a computer, control system, or the like, designed to provide ready access to data or instructions previously recorded.
MENTAL MODEL. Psychological construct describing an internal representation of a system used for predictions, control, and fault diagnosis.
MENTAL WORKLOAD. A measure of demands for cognitive activity or cognitive effort during the performance of a task.
MENU. A display of command options or data elements in a software application.
MENU BREADTH. The amount of options per menu screen in a menu system.
MENU DEPTH. The number of levels in a menu system.
MENU SYSTEM. A typically hierarchical arrangement of menus within a software application.
MENU NAVIGATION. The process of moving through a menu system.
METABOLIC RESERVES. The energy source stored in chemical form, such as carbohydrates, that can be efficiently mobilized and utilized by the body, particularly for muscular activity and work beyond the normal level of activity of an individual.
METABOLISM. The sum of all the physical and chemical processes by which living organized substance is produced and maintained; also the transformation by which energy is made available for the uses of organisms.
METHOD OF ADJUSTMENT. A psychophysical method used primarily to determine thresholds; in this procedure the subject varies some dimension of a stimulus until that stimulus appears equal to or just noticeably different from a reference stimulus.
METHOD OF CONSTANT STIMULI. A psychophysical method used primarily to determine thresholds; in this procedure a number of stimuli, ranging from rarely to almost always perceivable (or rarely to almost always perceivably different from some reference stimulus), are presented one at a time. The subject responds to each presentation: “yes-no," "same-different,” “greater than - equal to - less than,” etc.
METHOD OF EQUAL SENSE DISTANCES. A psychophysical method used primarily to scale sensations; in this procedure the subject adjusts a set of stimuli until the elements of the set appear to be equidistant along some dimension.
METHOD OF LIMITS. A psychophysical method used primarily to determine thresholds; in this procedure some dimension of a stimulus, or of the difference between two stimuli, is varied incrementally until the subject changes his response.
METHOD OF MAGNITUDE ESTIMATION. A psychophysical method used primarily to scale sensations; in this procedure the subject assigns to a set of stimuli numbers which are proportional to some subjective dimension of the stimuli.
METHOD OF MAGNITUDE PRODUCTION. A psychophysical method used primarily to scale sensations; in this procedure the subject adjusts a stimulus along some dimension until the magnitude of the stimulus appears equal to some specified magnitude.
METHOD OF PAIRED COMPARISONS. A psychophysical method used primarily to scale responses; in this procedure stimuli are presented in pairs to a subject who compares them along some dimension.
METHOD OF RANK ORDER. A psychophysical method used primarily to scale sensations; in this procedure stimuli are presented to a subject and he orders them along some dimension.
METHOD OF RATIO PRODUCTION. A psychophysical method used primarily to scale sensations; in this procedure the subject adjusts a stimulus along some dimension until that stimulus appears to be a specific fraction or multiple of a reference stimulus.
METHOD OF SINGLE STIMULI. A psychophysical method used primarily to scale sensations; in this procedure stimuli are presented singly to a subject who rates them along some dimension.
METS. A functional energy expenditure classification, using multiples of the resting metabolic value. Thus, 2 mets is two times resting metabolism.
MINIMUM SEPARABLE ACUITY. Smallest space between two lines that can be discriminated as a gap. It is measured in terms of the angle subtended by the gap, measured at the eye.
MNEMONIC. A technique or designed coding system to aid in memory storage or retrieval.
MODE. The internal state of a system which determines how controls or input commands are interpreted.
MODE ERROR. Selection of action inappropriate for the current system mode.
MONITOR. To observe, listen in on, keep track of, or exercise surveillance over by any appropriate means, as, to monitor radio signals; to monitor the flight of a rocket by radar; to monitor a landing approach.
MOTION AND TIME STUDY. A systematic study of work systems, which have the purposes of: (1) developing a preferred system and method (usually one with lowest cost); (2) standardizing this system and method; (3) determining the time required by a qualified and properly trained person working at a normal pace to perform a specific task or operation; (4) assisting and training a worker in the preferred method. Motion study (or methods design), finding the preferred method of doing work. Time study (or work measurement), determining standard time for performing a specific task. Taylor used the term time study almost indiscriminately—including what the Gilbreths called motion study—much to their chagrin, especially when he took time studies without first studying the “one best way.” (See Z94.17 WORK DESIGN & MEASUREMENT.)
MOTION PARALLAX. The apparent difference in rate of movement of two objects actually moving at the same velocity but at different distances from the observer.
MOTOR SKILL. The ability to achieve the more or less complicated adjustments of hands, fingers, legs, feet, or other parts of the body in an integrated, smoothly flowing sequence resulting in the performance of some act.
MOUSE. An input device moved by the hand along a flat surface to move a cursor on a display.
MULTIMEDIA. Information display presenting multiple formats or stimulating multiple sensory modalities.
MULTITASKING. The performance of multiple tasks simultaneously.
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