COMMUNICATION & DISPLAY DESIGN

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Introduction• Human activites and task involve some form of

communication, in which information is exchanced between one and more partisipants.

• People communicate with each other by talking, writing and various forms of non-verbal communication.

• People’s interactions with machines, tools, computers, consumer products, and other devices they use to perform tasks can also be viewed as a form of communication

• People tell machines or other devices what to do, using controls and input devices, and are told what to do and what not to do by displays, signs, signals, and other information-bearing cues in their environment.

Man-Machine

A communication system, as originally proposed b Shannon (1948), consists of :

1.An information source that produces the message(s) to be communicated

2.A transmitter that converts or codes the message into a signal suitable for transmission

3.A channel that transmits the signal from transmitter to receiver

4.A noise source that adds noise to channel5.A receiver that reconstructs or decodes the message

from the signal

An Abstract Communication System

Source of

Signal

Encoder & Signal

Decoder & Receiver

Destination of Signal

Internal noise

External Noise

Channel

These components of a communication system are generic in nature andcan be used to distinguish a wide variety of communication scenarios (Lehto& Miller, 1986)

Information Transmition• The succesfully communicate a message, the message must first be

sent.

• For example, a speedometer might display the current speed of vehicle. The intended receiver must then notice, understand and respon appropriately after receiving the message.

KLM Flight 4805, Boeing 747-206B, PH-BUF, ground collision with Pan American Flight 1736, Boeing 747-121, N735PA

• Location: Tenerife, Canary Islands (Spain)• Date: March 27, 1977

•Both aircraft - KLM Flight 4805, a Boeing 747-206B, Reg. No. PH-BUF; and Pan American (Pan Am) Flight 1736, a Boeing 747-121, Reg. No. N736PA, - had been diverted to Los Rodeos Airport on the Spanish island of Tenerife in the Canary Islands due to a bombing at the airport at their final destination, the neighboring island of Gran Canaria.

• Later, when flights to Gran Canaria resumed, the aircraft collided on the runway in Tenerife as the KLM Boeing 747 initiated a takeoff while the Pan Am aircraft was using the runway to taxi.

• The Spanish investigative authority, Subsecretaria de Aviacion Civil, found that the fundamental cause of the accident was the KLM captain:

1. Took off without clearance; 2. Did not obey the "stand by for take off" direction from the tower; 3. Did not interrupt take off on learning that the Pan Am aircraft was still on the runway; and 4. In reply to the KLM flight engineer's query as to whether the Pan Am aircraft had already left the runway, the KLM captain replied emphatically in the affirmative.

• The investigation also believed that the KLM captain's decision to take off may have been influenced by revised crew duty time limitations recently enacted by the Dutch government. The restrictions were inflexible and highly penalizing to the captain, if exceeded.

• With a total of 583 fatalities, the crash remains the deadliest accident in aviation history. All 248 passengers and crew aboard the KLM flight were killed. There were also 335 fatalities and 61 survivors on the Pan Am flight.

Incident

Man/People

Wrong sense

Wrong intepretation

Wrong decision

fatique,

sleppiness

Lack of knowledge

Lack of skill

Bad mood

Lack of communication

Machine

Hardware

Mechanical failure

software

Environment

virus

Method

Communication is not standardized

SOP wrong

Communication

Man People

MachineTools

ComputerProduct

INFORMATION

INFORMATIONINFORMATION

Noise

Capability / LimitationCapability / Limitation

Human Information Processing Model (Wickens, 1984)

How to Calculate Information (coin toss)

H = ∑pi * Log2(1/pi)

H = Log2nH : Amount of Information (bit)n : The number of equally likely alternatives

Pi : Probability of ith eventi : Alternatives from 1 to n

H = Log2 2 = 1 bit n=2

50% 50%

90% 10%

H = 0,9*Log2(1/0,9) + 0,1*Log2(1/0,1) = 0,9*0,152 + 0,1*3,32 = 0,469 bit

Latihan Soal

100% 0%

H = 1*Log2(1/1) + 0*Log2(1/0) = 0 + 0 = 0

Information ≈ Unexpected Event

Human Capability• Vary among Human

• Sensory storage of ear : 10.000 bits/sec (not including decision making process)

• Maximum information processing vary 6 – 50 bits/second

• (Freivalds, 2009)

Memorize in 10 second

1293458

234598456123

1. Chunking

2. Rehearsal3. Association

• Selective Attention• A general finding of early reseach on human information

processing was that people are limited in their ability to transmit information.

• People have a tendency to see or hear what they expect to see or hear

• The Role of Working Memory• When people perform tasks, they are constantly shuffling

information in and out of consciousness

• This process is nicely described by production system model of human cognition (Newel & Simon, 1972; Anderson, 1983)

1. Task performance is described in terms of the changing contents of working memory in which has a limited capacity of 5 to 9 items

2. The content of working memory changes over time when new information entering working memory replaces or over writes the existing contents

3. The new information can enter working memory when information from the environment is perceived or when fact are retrieved from long-term memory

Well integrated sources of information can act as cues that trigger the retrieval of additional, and hopefully relevant, information from long term memory

Providing information only at the time it is relevant also reduces the chance of overloading working memory and minimizes the change of distracting the operator

Example :

• Lockout tag is placed next to an activated lockout• Switched are labeled on control panel• Sign placed on a door warns against entering

• The Mode of Processing

• There are two modes of cognitive processing 1. One is outomatic, less capacity-limited, Possibly

parallel, Invoked directly by stimulus input

2. The second requires conscious control, has severe capacity limitations, is possibly serial and is invoked in response to internal goals

• Decision Making • The ultimate objective of the communication process is to

improve decision making of real people in real environments

DISPLAY DESIGN• Displays are devices designed to communicate messages

to people/machine/tools

Classical view of the human-machine interface (Chapanis, 1965)

• In most cases, display perform a supportive role, in which they supplement other sources of information that might be available to the person using the particular device

Types of display

• Visual display ; are the most encountered• Static display (ex : sign, label, book)• Dinamic display (ex : speedometer, fuel gauges, oil pressure, temperatur

indicator)• Analogue & Digital display• Warning or alerting display • Predictive or historical display • Instructional, command or advisory display • Spatial display (diagram, figuren & chart)• Symbolic display • Pictorial display (images)

• Auditory display; tend to used for alerting or warning related purposes (Wide array of sirens, horns, bells, tones, beeps or buzzers)

Principle of Display Design (1)

• Sensory Modality 1. The most appropriate sensory modality of a display depends on its

intended function, sensory demands of the background of the background task, and sensory capabilities of its intended audience

2. Display that combine sensory modalities can be particulary effective when tasks are performed under changing condition

• Display Location & Layout1. Locate visual displays where they can be seen and put more important

visual in more central locations

2. Display should provide their information at the time it needs to be used

3. Displays and display elements should be grouped consistently with the sequence in which they are used by the operators

4. Tasks requiring information integration are better served by more integrated object-like displays

Principle of Display Design (2)

1. Object that are placed close together will be more likely to be viewed as being related

2. Position displays or display elements so they have obvious spatial referents

Legibility of Display Element

1. The minimum size of a critical detail should be 5 minutes of visual arc for novice observers and not less than 2 minutes of visual arc for experienced operators

2. Symbols and alphanumeric characters should subtend a visual angle of at least 12 minutes of arc

3. Display should provide an adequate contrast between visual elements and their background

4. Avoid crowding of display elements

5. Take steps to deal with the effect of degraded legibility due to aging and adverse environmental conditions

For rapid and accurate identification of individual characters, 16 to 18 minutes of arcis normally adequate, although reading speed continues to increase until characterheight exceeds 22 arc minutes (Chung et al., 1998; Giddings, 1972; Legge et al.,1985; Legge et al., 1987; Legge et al., 1990; Strasburger et al., 1991).

A width-to-height ratio (“Width”/“Height” in Figure 7-4) shall be from 0.5 to 1 to 1to 1 and, for optimal legibility and readability, should be from 0.6 to 1 to 0.9 to 1.Legibility is sometimes sacrificed to some extent for esthetics, conservation of space,or other practical considerations (Benson, L., & Farrell, 1988; Soar, 1955).

Principle of Display Design (3)

• Information Content and Coding1. Display instructions should whenever possible be stated in a positive manner2. Be Selective3. Let the user control the amount and detail of information presented4. Information about the current or desired state or condition of system, item, 5. Display that mae derivative information easily available make it easier for people to

predict what will happen6. Be as realistic as possible in describing the variable you are trying to communicate7. The direction of movement of an indicator on a display should be compatible 8. Color coding is a good tool for conveying relationship between display elements; 9. Many coding schemes other than color, including shape 10. Verbal and numerical codes tend tobe better understood and requires less learning than

symbols or other coding methods11. The use of analogies and metaphors often can greatly improve the learnability and

understandability of display element 12. In most cases, line graph are preferred slightly over vertical bar graphs and preferred

strongly over horizotal bar graphs13. Multiple single line on single line are prefered over multiple single line graphs in point

reading 14. Varioation in pitch, amplitude, an modulation can be used to specified distinguished

sounds.

• Presentasi • ANSI-HFES 100, 2007• Kelompok 1 : bab 5• Kelompok 2 : bab 6• Kelompok 3 : bab 7• Kelompok 4 : bab 8• Kelompok 5 : bab 1,2,3,4

• Presentasi • ANSI-HFES 100, 2007• Kelompok 3 : bab 7• Kelompok 4 : bab 8

• Good and Bad Display• Contoh-contoh display (baddesign.com)• Standard (ukuran huruf, kontras, jarak pandang, dsb)