Z94.9 Human Factors (Ergonomics) Engineering

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DARK ADAPTATION. A process of neuro-chemical changes whereby the visual system becomes much more sensitive to light.

DATA ENTRY. Task in which information is entered into a computer.

DATA GLOVE. Input device consisting of a glove with sensors detecting finger movements.

DAZZLE. Extreme brightness of direct or reflected light that causes difficulty in seeing.

DEAD BAND. Loci of control positions, usually around the center position of a knob or lever, for which there is no control output.

DEADMAN CONTROL. Mechanism designed to remove or reduce hazardous energy to a safe level in the absence of the kind of force exerted by a conscious operator.

DEBUG. Removal of software errors.

DECIBEL. A logarithmic scale expressing quantities of sound, or electrical power, signal attenuation and gain. Measurement is relative to a specified reference level.

DECISION MAKING. Selection of action from a set of alternatives.

DECISION TIME. Delay attributable to cognitive processing of input data.

DELPHI METHOD. A procedure for obtaining the consensus of experts in areas such as long-range forecasts by successive iterations of questioning interspersed with feedback to each expert on the others’ opinions and supporting reasons.

DEPTH PERCEPTION. Visual discrimination along the dimension of distance from an observer, using monocular cues (e.g., interposition, accommodation, size) and/or binocular cues (convergence, stereopsis).

DESCRIBING FUNCTION. Mathematical model of human performance, especially in tracking tasks such as aircraft piloting.

DETECTABILITY. Quality of a signal, display, or stimulus that affects the probability of its presence being perceived.

DIALOG BOX. A display window for entering computer commands.

DICHOTIC. Pertaining to differential stimulation of the two ears.

DIOTIC. Pertaining to the stimulation of the two ears by identical stimuli.

DIFFERENCE LIMEN. Difference threshold-–the amount by which two supraliminal stimuli must differ if this difference is to be perceived in an exactly specified portion (usually 50 or 70%) of trials. (See LIMEN.)

DIRECT MANIPULATION. Computer interface in which commands are entered by actions upon displayed objects.

DISPLAY. The presentation of output data from a device or system in a form designed for human perception through vision, audition, or other sensory modality.

DISPLAY LAYOUT. The spatial organization of displays at an interface or workplace.

DISTRIBUTED CONTROL. System arrangement in which control activity is distributed among multiple controllers.

DISTRIBUTED DECISION MAKING. System arrangement in which decision making activity is distributed among multiple decision makers.

DOUBLE CLICK. Two clicks in rapid succession, as a method of computer input.

DYNAMIC DISPLAY. Display containing information that is updated autonomously.

DYNAMIC SYSTEM. A system whose state changes autonomously as well as through controller activity.

DYNAMIC VISUAL ACUITY. The measure of visual acuity used when a target moves with respect to an observer. (See VISUAL ACUITY.)

DYNAMOMETER. A device for measuring the strength of a muscular contraction; typically a hand-grip device with a scale showing squeeze force.


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