Chapter 3: Visual, Tactile, and Olfactory Displays

static display

display does not change (stop sign)

dynamic display

represent info that changes over time

(progress bar)

conspicuity

how well the sign attracts attention

visibility

how well a sign can be seen

legibility

ability to distinguish letters, numbers, and symbols from each other

readability

how text quality affect how easy a ready can read the text

advantage of using symbols/pictorials

don't need to be translations for person unfamiliar with the language

disadvantage of symbols and pictorials

user must be able to readily identify the symbol and recognize its referent

The readability of text depends on

visual angle

contrast

stroke width

font selection

visual angle

(3438 x height)/ distance

analog display

A display that shows continuous information, often using a pointer on a scale (e.g., speedometer)

digital dynamic displays

A display that presents information in discrete numeric or alphanumeric form (e.g., digital clock).

advantage of analog

Easier to interpret trends and direction of change.

disadvantage of analog

Hard to read exact numerical values.

advantage of digital

High precision—exact values are shown clearly.

disadvantage of digital

Difficult to detect trends or rate of change.

human factor in choosing display type

user mental models and task demands

factors that influence display location and arrangement

importance

frequency

sequence

functional organizations

quantitative displays

presents numerical data or values

navigation displays and map displays

spatial information

Why are labels important in quantitative displays?

They clarify what the numbers mean (e.g., °C vs. °F, speed vs. RPM), preventing misinterpretation.

Why are labels important in navigation displays/maps?

They help users identify locations, landmarks, or directions—especially in complex spatial layouts.

What role do symbols play in quantitative displays?

Symbols can simplify or highlight units or thresholds (e.g., warning icons at critical levels).

What role do symbols play in navigation displays?

They provide quick visual recognition of features (e.g., airports, hospitals, hazard zones).

Why is color important in quantitative displays?

To highlight critical values (e.g., red = danger, green = safe), and support rapid decision-making.

Why is color important in navigation displays?

To distinguish terrain types, routes, elevation, or alerts (e.g., blue = water, yellow = caution area).

accommodation

the process by which the eye's lens changes shape to focus near or far objects on the retina

duplex visual system

rod and cone photoreceptors

rod photoreceptors

scoptic /night vision

120 million rods in each retina

cone photoreactors

photopic /day vision

6 million cones in each retina

dark adaption

cones: 5 minutes

rods: 30 minutes

Purkinje shift

the shift from cone spectral sensitivity to rod spectral sensitivity that takes place during dark adaptation

visual acuity

sharpness of vision

color blindness

a variety of disorders marked by inability to distinguish some or all colors

how to reduce color limitation

high contrast, symbols,

depth perception

the ability to perceive the world in three dimensions

static cues

occlusion

size

textured gradient

parallel lines appear to converge in the distance (linear perspective)

atmospheric perspective

position relative to horizon

kinesthetic cues

provide information that allows you to sense that your body or limbs are moving or being moved

dynamic cues

motion parallax

moving, closer objects move faster across your view than farther ones

binocular cues

depth cues, such as retinal disparity, that depend on the use of two eyes

Each eye sees a slightly different image—brain fuses them for depth.

egocentric distance

the distance between oneself and things in the world

relative depth

perceive the ordering and relative separations of objects in depth without knowing their exact distances.

personal space

around 10 m around the person

uses convergence and communicative cues

action space

around 30 m

Occlusion, height in visual field, binocular disparity, motion perspective, and relative size.

30+ meteres

occlusion and relative size

illumination

effectiveness of many depth cues are compromised by low light

tactile displays

supplement visual or auditory information

example of tactile cues

vibration of phone

rumble strip on rodas

Proprioceptive cues

perception of the static position of the body and limbs in space

Merkel (disks) cells

Cells that signal the brain that an object has touched the skin; also called tactile cells

meissner corpuscles

respond to light touch

Pacinian corpuscles

respond to deep pressure and vibration

greatest tactile sensitivity

In the fingertips, thumb, and areas of the face, including lips, cheeks, and nose

Where are two-point discrimination thresholds best?

In the fingertips, nose, lips, and cheeks.

Where are two-point discrimination thresholds poorest?

In the upper arm, calf, thighs, and back.

active touch

Touch in which the observer plays an active role in touching and exploring an object, usually with his or her hands.

passive touch

occurs when touch stimuli are applied to the skin, as when two points are pushed onto the skin to determine the two-point threshold.

Olfactory Displays

-related to sense of smell

-ex: stinky smell is added to natural gas so you know recognize it, it's naturally odorless

-ex: wintergreen scent added to carbon dioxide when a fire is detected

limitations with olfactory display

quickly desensitized to odors

distraction caused by active dispersal of odorants