Vision & Hearing
What is the NIOSH recommended maximum time weighted dB level?
Weighted average of 85dB for an 8 hour shift.
Name the main components of the HIP model.
Perceptual encoding (sensory register and perception), central processing (attention, DM, WM, LTM), responding (response selection, execution)
A traffic light, is a good example of this principle, as the 3 states of information are coded into both positions (top, middle, bottom) and colors (red, yellow, green).
Redundancy gain.
Define SDT.
“Framework to describe and study decisions that are made in uncertain or ambiguous situations”
A means to quantify the ability to discern between a signal and the absence of signal (or noise)
What is a contrast ratio?
The ratio of character luminance:background luminance.
What is the difference between rods and cones (purpose and distribution within the eye)
Rods: sensitive to light, poor spatial res, no color discrimination, night vision, outside fovea
Cones: Colors, daylight vision, in fovea
What is the term for the mental process of transforming sensory input into meaningful information?
Perception.
Provide an example for the principle of multiple resources.
Multimodal interfaces: audiovisual, audio-haptic, visuo-haptic etc.
Define sensitivity (d') and criterion (c)?
d': separate of noise and the (noise+)signal curves.
c: the judgement of decision criterion of the observer
Explain scaling (A vs. C) and time weighting (fast vs. slow) and explain when each is used.
Scale used to calculate dB values (A is typically used; C is used for louder sounds)
Time weighting weighs sound exponentially with time (slow for most occupational assessments; fast to determine peak values)
Define luminance and illuminance and provide an example of each.
Luminance: light reflected or emitted by surface
Illuminance: light falling on the surface
Art example. Luminance is the light coming off art work; illuminance describes the light hitting the art from the overhead lighting.
What is the difference between working and long-term memory?
WM: mental "scratch pad"; used during rehearsing, planning, visualizing, etc.; short-term store for needed for certain mental tasks
LTM: mental models of how world works; the repertoire of past experiences and knowledge; Learning occurs when WM content goes into LTM.
Give an example of how lack of discriminability may have life-threatening consequences.
Failing to discriminate between two medications
Failing to discriminate or notice a stop signal, red light etc.
What are the assumptions of SDT?
Response is yes or no.
Info is based on uncertainty.
2 normal distributions.
How can SDT inform display design?
- Optimizing d' to make signals more distinct from background noise.
- Minimizing false alarms.
- Usability testing: assessing design effectiveness in terms of sensitivity, response criteria, and overall user performance.
What is visual acuity and what are factors that affect it?
Visual acuity: measure of the ability of the eye to distinguish shapes and the details of objects at a given distance
Factors: brightness, contrast, glare, target movement, visual problems
List and define the four factors influencing selective attention.
SEEV (salience, effort, expectancy, value)
Instead of showing gradually changing colors, it is better to show discrete changing of colors, e.g. divided into 5 distinct levels, so it’s easily distinguishable.
Avoid absolute judgement limits.
*Which error is more costly and critical, a false positive (false alarm) or false negative (miss)? Justify your answer.*
It depends on the context.
For instance, in the context of medical screening and airport bag screening, a FN may be more costly than a FP.
What are the four visual search strategies, and how do they involve bottom-up or top-down processing?
Serial: one after the other
Parallel: items examined in parallel
Conspicuity: bottom-up
Expectancies: top-down
*What do the contours in the loudness graph mean?*
Different frequency and SPL (dB) combinations where it is perceived to be equivalent at 10, 20, etc. phon.
Phon = unit of loudness
*Bailey is searching for her car keys in the morning. Is she using bottom-up or top-down processing? Justify.*
Both. Bailey's search is driven by bottom-up stimuli (salient colors, shapes, etc.) as well as top-down factors (expectations, scene semantics).
*For each of the 4 categories of display principles: (1) name a principle and (2) provide an example.*
•Four categories of display principles (Ch. 8.2):
A. Perceptual – How user initially perceives material presented (5 principles)
B. Mental model – Users interpret displays based on their expectations (based on past experience) of the system being displayed (2 principles)
C. Attention – considers multitasking, types of attention (3 principles)
D. Memory (3 principles)
You are conducting a perception experiment in which participants are asked to detect the presence or absence of a faint sound in a noisy environment. Participants are given two response options: "Yes" to indicate they heard the sound, and "No" to indicate they did not hear the sound.
Based on your data analysis, you find the following:
Calculate hit rate and false alarm rate.
HR = TP/(TP + FN) = 40/70
FAR = FP/(FP + TN) = 10/70
*Prof. Riggs wants Peiyu to design the interface of a website aimed to help the elderly book vacation trips, and Peiyu does not have the slightest clue of how to begin. Provide Peiyu with initial guidelines of: (1) factors to consider, (2) design recommendations.*
Elderly are more likely to have visual acuity and hearing loss issues. Icons and buttons should probably be bigger, more intuitive, and largely spaced. Avoid display clutter.