motor gain Flashcards
(45 cards)
What is the difference between actions, input devices, and controls?
Actions are human motions, input devices translate those into signals, and controls determine what functions are triggered.
What does the control-display relationship describe?
How user input is mapped to output or system feedback (e.g., moving a mouse moves a cursor).
What are modes in UI design?
Modes allow the same input to have different effects depending on the system state (e.g., CAPS LOCK, editing/view mode).
What are mode errors?
Mistakes caused by forgetting or misinterpreting which mode the system is in, often due to subtle or missing feedback.
What is an example of a fatal mode error?
Air Inter Flight 148 crashed due to confusion between descent angle (3.3°) and vertical speed (3300 ft/min), both shown as ‘33’ or ‘3.3’ on the same display.
What is manual input?
Input using fingers (typing, tapping, gestures), hands (mouse movement), or touch interactions that translate actions to digital input.
What are some non-manual input methods?
Feet (pedals), head pointing, voice commands, body gestures, facial expressions, and eye tracking.
What is the layered model of input?
A hierarchy where physical actions trigger switches that produce scan codes, interpreted into characters or actions by software.
What are hard controls?
Physical devices like keyboards, mice, buttons, scroll wheels, and joysticks that generate input signals.
What are soft controls?
UI elements like buttons or sliders rendered on a screen, usually manipulated via hard controls like a mouse or touch.
What’s the difference between explicit and implicit control?
Explicit control involves intentional user input; implicit control arises from interpreting user behavior (e.g., device orientation).
What is spatial matching in UI controls?
When input is mapped to screen position (e.g., clicking a button), as opposed to semantic matching (e.g., pressing a shortcut key).
What is CD gain?
Control-display gain is the ratio of pointer movement to input device movement. High CD gain allows faster pointer movement with smaller physical effort.
What affects CD gain in modern systems?
Mouse velocity: fast movement increases CD gain (non-linear), allowing quicker cursor travel over larger areas.
What is latency in input systems?
The delay between a user action and the system’s response; if above 0.1s, users notice the lag and experience degraded interaction.
“What is the perceptual threshold for responsiv
What is input performance in HCI?
It refers to how long it takes a user to complete a task or subtask, commonly measured using time-on-task.
Why is low-level input efficiency important?
Low-level tasks like clicking or typing should be quick so they don’t distract from high-level goals.
What is the Keystroke Level Model (KLM)?
A predictive model that estimates expert user task time using a sequence of physical, mental, and system operations.
What are the KLM operators?
K = keystroke, P = pointing, H = hand move, M = mental prep, B = button press; each has a time value used in summing task duration.
When is a mental operator (M) added in KLM?
When the user must think, such as initiating a task, making a decision, or locating an item.
What are limitations of KLM?
It models only expert users, doesn’t handle errors or learning, and can’t detect standard usability issues.
What is a weakness of KLM for pointing?
It assumes a constant time (1.1s), ignoring factors like distance, size, or input device variation.
What is Fitts’ Law?
A model predicting pointing time based on target distance (D) and width (W), using the formula MT = a + b log₂(D/W + 1).
