HUMAN COMPUTER INTERACTIONhy364/files/lectures/02_Human... · 2020-02-06 · 1st Part: The human We...

HY-364: Επικοινωνία Ανθρώπου - Μηχανής Slide 1HY-364: Επικοινωνία Ανθρώπου - Μηχανής Slide 1HY-364: Επικοινωνία Ανθρώπου - Μηχανής Slide 1

COURSE CS-364 (OPTIONAL)

HUMAN – COMPUTER INTERACTION

UNIVERSITY OF CRETE

FACULTY OF SCIENCES AND ENGINEERING

COMPUTER SCIENCE DEPARTMENT

1st Part: The human We discuss the user’s:

▪ Psychological and▪ Physiological attributes▪ A basic overview of the capabilities and limitations that

affect our ability to use computer systems

2nd Part: The computer Input and output devices are described and the effect

that their individual characteristics have on theinteraction is highlighted

3rd Part: The interaction We discuss the dialogue between the human and the

computer

Slide 2CS-364: Human – Computer Interaction

Model Human Processor (Card, Moran & Newell, 1983). Themodel comprises three subsystems: Perceptual system: handles sensory stimulus from the outside world

Motor system: controls actions

Cognitive system: provides the necessary processing to connect thefirst two subsystems

User as an information processing system:1. Input – output

2. Memory

3. Processing

We are dealing with an intelligent information-processing system, andprocessing therefore includes problem solving, learning, andconsequently, making mistakes


Input in the human occurs mainlythrough the senses and outputthrough the motor control of theeffectors

Major senses:

Vision, hearing, touch, taste andsmell

The first three are the mostimportant for HCI


Vision is a two-step process:

1. Begins with the physical characteristics of theeye, which enables us to see objects (physicalreception of stimulus)

• objects have to be large enough, with enoughcontrast, in a visible colour, and so on, that theeyes can register them

2. In the second step, retinal signals aretransferred to the brain (processing andinterpretation of stimulus)

• once we see an object clearly, we have tointerpret what we see (e.g. what is this icon?)


Primary source of information (for ‘normally’ sighted persons)

Use visual feedback and visual means for attracting attentionwhen:

The information is long and complex

The information will be referred to later

The user’s aural system is already overburdened

The user is not moving about

A verbal response is not needed

Illumination is good

For alerts and warnings which do not need the user’simmediate attention

Design considerations will be presented in the Visual andInformation Design lecture


The most important sense after vision Particularly important for speech

Less used in user interfaces Annoying for others

Less directional / More diffuse

The information transfer rate is less than that of vision Consequently, sound cannot be used to present large

amount of information


Sound output can not be used incertain working environments

e.g., many workstations in the sameroom

For blind people hearing is aprimary input channel


Simple sounds (beep, ring and buzz) Attention grabbing and feedback

Ecological (thump and gurgle) What is happening

Use sound for feedback and attracting attention when:

The information is short and simple

The information will not be referred to later

When an immediate response is needed

The visual system is already overburdened

The user is moving about from place to place

A verbal response is needed

Poor illumination makes vision unreliable


Touch provides us with valuable information on ourenvironment As far as interacting with computer systems is concerned,

touch is the third most important sense after vision andhearing

Although for the average person, haptic perception is asecondary source of information, for those whose othersenses are impaired, it may be vitally important (e.g., Brailleinterfaces)


Conveys important subconsciousinformation

Can be used in areas of high auditory orvisual noise where an additionalchannel is used to provide user’sattention (e.g., vibrating mobilephones)

It is closely associated with ergonomicdesign aspects of a system

Design of input devices (‘feel’ ofkeyboard, shape of mouse, etc.)


Taste and smell are not particularly usefulin Human-Computer Interface design

They are not very accurate in mostpeople

They are highly dependent upon health

They can be trained (e.g., wine experts)

Implications to UI design: you cannot relyon these senses, however they can beused as redundant feedback


How the way we move affects our interaction withcomputers

Movement time and accuracy are two important issues indesigning interactive systems Movement time is obviously dependent largely on the

physical characteristics of human (e.g., age and fitness) Reaction time should not be underestimated as well In some cases requiring increased reaction time

reduces accuracy▪ In many arcade and video games, less skilled users fail at levels that

require faster responses▪ However for skilled operators this is not necessarily the case

▪ Studies on keyboard operators have shown that although the faster operatorswere up to twice as fast as the others, the slower ones made 10 times theerrors


The sensory memories act asbuffers for stimuli receivedthrough the senses. A sensorymemory exists for eachsensory channel

Short-term memory acts as a‘scratch-pad’ for temporaryrecall of information

Long-term memoryAttentionSensory stores

(Iconic, Echoic, Haptic)

Short-term memoryor

Working memory

Rehearsal &

Information

Processing


Long-term memory is the repository of allour knowledge and who we are It has a huge (if not unlimited) capacity

Has a relatively slow access time

Forgetting occurs more slowly, if at all

Mezzanine memory (not a formal name) Understudied

The in-between stuff, things we remember forminutes, hours or perhaps days (think aboutthe exams!)

Rehearsal commits to long-term memory


Decaying time: 30s (without repetition)

Miller’s Magic Number (7+/-2 chunks)

More can be remembered if the items can bechunked (grouped together)

810594737 vs. 810 - 594 – 737

Interface implications

It is advisable to try not to present more than 7 +/- 2items to the user for recall

Keep-in track where the user has been


Two important factors influencing memory performance (Ebbinghaus) :

The delay between learning and recall of information

The amount of information to be remembered

Example:


List most recently used fonts Present example letters

Memory for arbitrary things

The items to be retained seem arbitrary, with no meaning and noparticular relationship to one other or to things already known

Arbitrary knowledge can be classified as the simple remembering ofwhat is to be done, without reliance on understanding, e.g.:

▪ Learn the alphabet

▪ How to use an operating system: “press Control + Alt + Delete”

Memory for meaningful relationships

The items to be retained form meaningful relationships with themselvesor with other things already known

When things make sense, new material can be understood, interpreted,and integrated with previously acquired material

Rules and constraints can help understand what things go together


Memory through explanation

The material does not have to be remembered, but rather can bederived from some explanatory mechanism

The most powerful form of internal memory: understanding

Mental models play a major role

People make up mental models for most of the things they do

This is why designers should provide users with appropriate models


Closure gives a nice “done it” when we complete some part of a task

At this point our minds have a tendency to flush short-term memory in order to get on with the next job

Early automatic teller machines (ATMs) gave the customer money before returning their bank card.

On receiving the money the customer would reach closure and hence often forget to take the card

Modern ATMs return the card first


How memory is processed and manipulated:

Reasoning

Problem solving

Skill acquisition

Errors and mental models


Reasoning is the process by which we use theknowledge we have to draw conclusions or infersomething new about the domain of interest

Types of reasoning:

Deductive reasoning. Derives the logically necessaryconclusions from the given premises▪ E.g. If it is Friday I will go to work. It is Friday. Therefore I

will go to work

Inductive reasoning. Generalisation from cases wehave seen to infer information about cases wehaven’t seen▪ E.g. If every elephant we have seen has a trunk, we infer

that all elephants have trunks

Abductive reasoning. From a fact to the action orstate that caused it▪ E.g. We know that John always drives too fast when he

has been drinking. If we see John driving too fast we mayinfer that he’s been drinking


The process of finding a solution to an unfamiliar task usingthe knowledge we have

How do people solve problems?

The Gestalt view▪ Problem-solving involves both reuse of knowledge and insight

The problem space theory▪ The human mind is a limited information processor▪ The problem space comprises problem states and problem-solving

involves generally these states using legal state transition operators)

Analogy in problem-solving▪ Problem solving is done by mapping knowledge relating to a similar

known domain to the new problem. Similarities between the knowndomain and the new one are noted and operators from the knowndomain are transferred to the new one


All of the problem solving that we have considered so farhas concentrated on handling unfamiliar problems.However, for much of the time, the problems that we faceare not completely new

Instead, we gradually acquire skill in a particular domainarea

In Anderson’s skill acquisition model (ACT), three basiclevels of skill are identified:

1. The learner uses general-purpose rules which interpret factsabout a problem

2. The learner develops rules specific to the task

3. The rules are tuned to speed up performance


People make errors routinely:

Trivial, resulting to temporary inconvenience or annoyance▪ Use salt instead of sugar

Serious, requiring effort to correct▪ Deleting the file you have been typing

the last two hours

Catastrophic, that can not be corrected▪ Plane crashes, nuclear accidents


Μental models are used by people to reason about a system and, in particular, to try to fathom out what to do when something unexpected happens with the system or when encountering unfamiliar systems

The more someone learns about a system and how it functions, the more their mental model develops For example, TV engineers have a deep mental model of how TVs work

that allows them to work out how to set them up and fix them. In contrast, an average citizen is likely to have a reasonably good mental model of how to operate a TV but a shallow mental model of how it works

They are often partial

They are unstable and subject to change

They can be internally inconsistent, since the person may have not worked through the logical consequences of their beliefs


You arrive home from a holiday on a cold winter's night to a cold house. You have a small baby and you need to get the house warm as quickly as possible. Your house is centrally heated. Do you set the thermostat as high as possible or turn it to the desired temperature (e.g. 20°C)?

You arrive home after being out all night and you're starving hungry. You look in the freezer and find all that is left is a frozen pizza. The instructions on the packet say heat the oven to 180°C and then place the pizza in the oven for 20 minutes. Your oven is electric. How do you heat it up? Do you turn it to the specified temperature or higher?


Most people when asked the first question imagine the scenario in terms of what they would do in their own house and choose the first option. A typical explanation is that setting the temperature to be as high as possible increases the rate at which the room warms up. While many people may believe this, it is incorrect. Thermostats work by switching on the heat and keeping it going at a constant speed until the desired set temperature is reached, at which point it cuts out. They cannot control the rate at which heat is given out from a heating system

When asked the second question, most people say they would turn the oven to the specified temperature and put the pizza in when they think it is at the right temperature. Some people answer that they would turn the oven to a higher temperature in order to warm it up more quickly. Electric ovens work on the same principle as central heating, and so turning the heat up higher will not warm it up any quicker


How can we apply psychology knowledge in designinginteractive systems? Guidelines

General design principles and guidelines can be derived from thetheories we have discussed

Models to support designPsychological theory has led to the development of analytic andpredictive models of user behaviour. Some of these include specificmodels of human problem solving, others of physical activity and othersattempt a more comprehensive view of cognition

Techniques for evaluationPsychology provides a range of empirical techniques which we canemploy to evaluate our designs and our systems


Interface designers should be aware of:

The properties of all the devices that comprise a system

All the factors that influence the interface behaviour, since theyinfluence the nature and style of the interaction

The computer:

The participant in the interaction that runs a program

Input – Output

Memory (short-term: RAM, long-term: disks etc.)

Processing


1. Text entry

Physical and Virtual Keyboards

Handwriting & optical character recognition

Speech recognition

2. Pointing & positioning devices

Mouse

Other 2D positioning devices (Trackball, Joystick, Touch Screens, etc.)

Positioning in 3D space (3D mouse, virtual reality helmets, etc.)


1. Displays

Cathode ray tube (CRT)

Liquid crystal display (LCD)

3D displays

Wearables and Head Mounted Displays (HMDs)

Large displays and situated displays

Digital paper


2. Auditory output devices

Designed to be used in conjunction with screen displays

Sounds offer an important level of feedback in interactivesystems

3. Haptic devices

…and paper (Printers and scanners)


Computers which run interactive programs are capable ofprocessing of the order of billion instructions per second

The speed of processing can affect the user interface

Faults when processing speed is too slow▪ The program does the wrong thing

▪ E.g., while playing a graphics-intensive 3D game, a bullet might hityou even if you pressed the key to avoid it as the processor was toobusy and decided to skip your command

▪ The program does the right thing, but the feedback is too slow

▪ E.g., assume that you want to delete an entire line of text byconstantly pressing the backspace key. If your computer is “busy”with another task, then you might end-up deleting more charactersthan needed as the cursor might not be rendered in time


Faults when processing speed is too fast▪ The user must be able to read and understand the output

of the system▪ E.g., Usually during the installation process of a program, many

informative messages that list the files that have been successfullycopied are printed in the console

▪ However, they change so fast that a user might not be able to read them

▪ Such issues influenced the introduction of the “progress bar”


Having looked at the human and the computer, we turn our attention to the dialog (interaction) between them

Contents

Norman’s execution-evaluation cycle

The interaction framework

The context of interaction

Interaction types and styles


Forming the intention

to succeed our goal

Interpreting the system state

(based on perception)

Examination / perception of the

new system state

Executing the

action

Specifying the action

sequence

Evaluating the system state

with respect to the user’s

goals and intentions

WORLD

Exe

cu

tio

n

Evalu

ation


The seven stages form an approximate model, not a complete psychological theory In particular, the stages are almost certainly not discrete entities

Most behavior does not require going through all stages in sequence, and most activities will not be satisfied by single actions

There must be numerous sequences, and the whole activity may last hours or even days

There is a continual feedback loop, in which the results of one activity are used to direct further ones, in which goals lead to subgoals, intentions lead to subintentions

There are activities in which goals are forgotten, discarded, or reformulated


How Easily Can One:

Determine The Function

of the Device?

Tell What Actions

Are Possible?

Determine Mapping

from Intention to

Physical Movement?

Perform the Action?

Tell if System is

in Desired State?

Determine Mapping

from System State

to Interpretation?

Tell What State

the System is In?


The seven-stage structure can be a valuable design aid, for it provides a basic checklist of questions to ask to ensure that the Gulfs of Evaluation and Execution are bridged.

In general, each stage of action requires its own special design strategies and, in turn, provides its own opportunity for disaster.

CS-364: Human – Computer Interaction

The gulf of execution and the gulf of evaluation describe the gaps that exist between the user and the interface

They are intended to show how to design the latter to enable the user to cope with them

The first one – the gulf of execution – describes the distance from the user to the physical system while the second one – the gulf of evaluation – is the distance from the physical system to the user


Norman and his colleagues suggest that designers and users need to concern themselves with how to bridge the gulfs in order to reduce the cognitive effort required to perform a task

This can be achieved, on the one hand, by designing usable interfaces that match the psychological characteristics of the user (e.g. taking into account their memory limitations) and, on the other hand, by the user learning to create goals, plans, and action sequences that fit with how the interface works


Attempts a more realistic description ofinteraction, explicitly including the system

Breaks interaction into four majorcomponents:

User formulates the desired task to achievesome goal needs (and provides input to thesystem)

The input is translated to stimuli for the System

System responses are translated to stimuli forthe Output component, in order to becommunicated to the User

The User must interpret the output to evaluatewhat has happened

O

output

I

input

U

task

S

core


Interaction is affected by:

Physical factors of the environment

Social and organizational factors▪ In order to perform well, users must be motivated

▪ The user may lose his motivations, if the system does not match the actual requirements of the job to be done

▪ The introduction of new technology may prove to be a motivation to users

▪ Providing adequate feedback is an important source of motivation for users


Interaction can be seen as a dialogue between the computer and the user

The choice of interaction style can have a profound effect on the nature of this dialogue

“Interface types” as a generic term includes all the ways in which users communicate or interact with computer systems

Older term: “Interaction styles”, a collection of interface objects and associated interaction techniques



1. Command-based2. WIMP and GUI3. Multimedia4. Virtual reality5. Information visualization and dashboards6. Web7. Consumer electronics and appliances8. Mobile9. Speech10. Pen11. Touch12. Air-based gesture13. Haptic14. Multimodal15. Shareable16. Tangible17. Augmented and mixed reality18. Wearable19. Robots and drones20. Brain–computer interaction (BCI)

Preece et al (2015) identify 20 interface types

HUMAN COMPUTER INTERACTIONhy364/files/lectures/02_Human... · 2020-02-06 · 1st Part: The human We...

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