human computer interaction basics

Human Computer Interaction

Natnael Gonfa

April 15, 2023 Hawassa University Institute of Technology (School of Informatics)

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Brief Introduction

• Human Computer Interaction is about designing computer systems so the user can carry out their activities productively and safely.

• It is not how easy something is to use it is about how usable it is.

• It is a discipline concerned with the design, evaluation and implementation of interactive computer systems for human use and with the study of major phenomena surrounding them.


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When thing go wrong

• In some case it is easier to see when the HCI is bad and need to improve.

• If a customer order a special software and then never uses it, it can be because of the bad HCI.


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Goals of HCI

• To develop usable, safe and functional computer systems.

• Usability is concerned with making systems easy to learn and easy to use.

Chapter 1

Human Factors


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Human Factors

• Human Factors concerned with the fit between the user, equipment and their environments.

• It takes account of the user's capabilities and limitations in seeking to ensure that tasks, functions, information and the environment suit each user.

• human factors specialists or ergonomists consider the job (activity) being done and the demands on the user; the equipment used (its size, shape, and how appropriate it is for the task), and the information used (how it is presented, accessed, and changed).


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• Cognitive Principles

• Understanding the user designing for humans


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Overview

• What is cognition?• What are users good and bad at?• Describe how cognition has been applied to

interaction design• Mental Models• Internals classic theories of cognition• More recent external theories of cognition


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Why do we need to understand users?

• Interacting with technology is cognitive• Need to take into account cognitive processes

involved and cognitive limitations of users• Provides knowledge about what users can and

cannot be expected to do• Identifies and explains the nature and causes of

problems users encounter• Supply theories, modelling tools, guidance and

methods that can lead to the design of better interactive products


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Cognitive processes

• Attention

• Perception and recognition

• Memory

• Problem-solving, planning, reasoning and decision-making


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Attention

• Selecting things to concentrate on at a point in time from the mass of stimuli around us

• Allows us to to focus on information that is relevant to what we are doing

• Involves audio and/or visual senses

• Focussed and divided attention enables us to be selective in terms of the mass of competing stimuli but limits our ability to keep track of all events

• Information at the interface should be structured to capture users’ attention, e.g. use perceptual boundaries (windows), colour, reverse video, sound and flashing lights


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Activity: Find the price of a double room at the Holiday Inn in Bradley


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Activity: Find the price for a double room at the Quality Inn in Columbia


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Activity

• Tullis (1987) found that the two screens produced quite different results– 1st screen - took an average of 5.5 seconds to search– 2nd screen - took 3.2 seconds to search

• Why, since both displays have the same density of information (31%)?

• Spacing– In the 1st screen the information is bunched up

together, making it hard to search– In the 2nd screen the characters are grouped into

vertical categories of information making it easier


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Design implications for attention

• Make information salient when it needs attending to

• Use techniques that make things stand out like color, ordering, spacing, underlining, sequencing and animation

• Avoid cluttering the interface with too much information

• Avoid using too much because the software allows it


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An example of over-use of graphics


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Perception

• How information is acquired from the world and transformed into experiences

• Obvious implication is to design representations that are readily perceivable, e.g.– Text should be legible– Icons should be easy to distinguish and read


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Is color contrast good? Find italian


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Are borders and white space better? Find french


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Activity

• Weller (2004) found people took less time to locate items for information that was grouped – using a border (2nd screen) compared with

using color contrast (1st screen)• Some argue that too much white space on

web pages is detrimental to search– Makes it hard to find information

• Do you agree?


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Which is easiest to read and why?

What is the time?

What is the time?

What is the time?

What is the time?

What is the time?


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Design implications

– Icons should enable users to readily distinguish their meaning

– Bordering and spacing are effective visual ways of grouping information

– Sounds should be audible and distinguishable– Speech output should enable users to

distinguish between the set of spoken words– Text should be legible and distinguishable from

the background– Tactile feedback should allow users to

recognize and distinguish different meanings


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Memory

• Involves first encoding and then retrieving knowledge

• We don’t remember everything - involves filtering and processing what is attended to

• Context is important in affecting our memory (i.e. where, when)

• We recognize things much better than being able to recall things


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Processing in memory

• Encoding is first stage of memory– determines which information is attended to in the

environment and how it is interpreted• The more attention paid to something…• The more it is processed in terms of thinking

about it and comparing it with other knowledge… • The more likely it is to be remembered

– e.g. when learning about HCI, it is much better to reflect upon it, carry out exercises, have discussions with others about it, and write notes than just passively read a book, listen to a lecture or watch a video about it


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Context is important

• Context affects the extent to which information can be subsequently retrieved

• Sometimes it can be difficult for people to recall information that was encoded in a different context:– “You are on a train and someone comes up to you and

says hello. You don’t recognize him for a few moments but then realize it is one of your neighbors. You are only used to seeing your neighbor in the hallway of your apartment block and seeing him out of context makes him difficult to recognize initially”


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Activity

• Try to remember the dates of your grandparents’ birthday

• Try to remember the cover of the last two DVDs you bought or rented

• Which was easiest? Why?• People are very good at remembering visual

cues about things– e.g. the color of items, the location of objects and marks

on an object

• They find it more difficult to learn and remember arbitrary material – e.g. birthdays and phone numbers


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Personal information management

• Personal information management is a growing problem for many users– vast numbers of documents, images, music files, video

clips, emails, attachments, bookmarks, etc.,– where and how to save them all, then remembering

what they were called and where to find them again– naming most common means of encoding them – but can be difficult to remember, especially when have

1000s and 1000s – How might such a process be facilitated taking into

account people’s memory abilities?


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Personal information management

• Memory involves 2 processes– recall-directed and recognition-based scanning

• File management systems should be designed to optimize both kinds of memory processes– e.g. Search box and history list

• Help users encode files in richer ways – Provide them with ways of saving files using colour,

flagging, image, flexible text, time stamping, etc


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Design implications

• Don’t overload users’ memories with complicated procedures for carrying out tasks

• Design interfaces that promote recognition rather than recall

• Provide users with various ways of encoding information to help them remember– e.g. categories, color, flagging, time stamping


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Problem-solving, planning, reasoning and decision-making

• All involves reflective cognition– e.g. thinking about what to do, what the

options are, and the consequences • Often involves conscious processes, discussion

with others (or oneself), and the use of artifacts – e.g. maps, books, pen and paper

• May involve working through different scenarios and deciding which is best option


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Design implications

• Provide additional information/functions for users who wish to understand more about how to carry out an activity more effectively

• Use simple computational aids to support rapid decision-making and planning for users on the move


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Mental models

• Users develop an understanding of a system through learning about and using it

• Knowledge is sometimes described as a mental model:– How to use the system (what to do next)– What to do with unfamiliar systems or unexpected

situations (how the system works)

• People make inferences using mental models of how to carry out tasks


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Mental models

• Craik (1943) described mental models as:– internal constructions of some aspect of the

external world enabling predictions to be made

• Involves unconscious and conscious processes– images and analogies are activated

• Deep versus shallow models – e.g. how to drive a car and how it works


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Gestalt psychology

• Perception = recognition of objects from• basic visual elements• The whole gestalt is greater than the sum• of its parts• When elements are placed in groups that• define an object we tend to see the group• and not the object• Discover the principles used by the visual• system to group elements


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Gestalt principles

• Principles to describe how people tend toorganize visual elements into a meaningfulwhole– Figure/Ground– Proximity– Similarity– Symmetry– Continuity– Closure

–http://graphicdesign.spokanefalls.edu/tutorials/process/gestaltprinciples/gestaltprinc.htm


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Figure-ground

• We perceive our environment by differentiating between objects and their backgrounds

• We have a natural tendency to perceive gestalt, whole entities

• We strive to find the simplest solutions to incomplete visual information –


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What do you see here?


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Similarity• Things which share visual characteristics

such as shape, size, color, texture, or orientation are seen as belonging together

• Unity occurs because the triangular shapes at the bottom of the eagle symbol look similar to the shapes that form the sunburst.

• The figure on the far right becomes a focal point because it is dissimilar to the other shapes.


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Similarity 2

• When similarity occurs, an object can be

emphasized if it is dissimilar to the others.This is called anomaly.• Focal point of attention


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Proximity

• When elements are placed close together.

They tend to be perceived as a group.


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Common Fate

• When objects move in the same direction,

we tend to see them as a unit.

• http://www.andyrutledge.com/commonfate.

php


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Law of good continuation

• Contours based on smooth continuity are

preferred to abrupt changes of direction• The tendency to perceive unseen

parts ofan object as continuing in a predictable way


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Closure• Closure occurs when an object is

incomplete or a space is not completely

enclosed• If enough of the shape is indicated,

peopleperceive the whole by filling in the missingInformation.


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Conclusion

• Gestalt Principles can be used to impose a logical structure on UI’s

• help people create logical groupings

and increase visibility and comprehensibility of UI


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Understanding users’ needs

• Need to take into account what people are good and bad at

• Consider what might help people in the way they currently do things

• Think through what might provide quality user experiences

• Listen to what people want and get them involved

• Use tried and tested user-centered methods


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Activity

• How does making a call differ when using a:– Cell phone– Public phone box?

• Consider the kinds of user, type of activity and context of use


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What is interaction design?

• Designing interactive products to support the way people communicate and interact in their everyday and working lives

– Sharp, Rogers and Preece (2011)

• The design of spaces for human communication and interaction

– Winograd (1997)


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Goals of interaction design

• Develop usable products– Usability means easy to learn, effective

to use and provide an enjoyable experience

• Involve users in the design process


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HCI and interaction design


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Relationship between ID, HCI and other fields

• Academic disciplines contributing to ID: – Psychology– Social Sciences– Computing Sciences– Engineering– Ergonomics– Informatics


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Relationship between ID, HCI and other fields

• Interdisciplinary fields in interaction design:

– HCI– Ubiquitous Computing– Human Factors– Cognitive Engineering– Cognitive Ergonomics– Computer Supported Co-operative Work– Information Systems


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Design principles

• Generalizable abstractions for thinking about different aspects of design

• The do’s and don’ts of interaction design

• What to provide and what not to provide at the interface

• Derived from a mix of theory-based knowledge, experience and common-sense


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Understanding the user designing for humans

• Visibility • Feedback• Constraints• Consistency • Affordances


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Visibility

• This is a control panel for an elevator

• How does it work?

• Push a button for the floor you want?

• Nothing happens. Push any other button? Still nothing. What do you need to do?

It is not visible as to what to do!


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Visibility

…you need to insert your room card in the slot by the buttons to get the elevator to work!

How would you make this action more visible?

• make the card reader more obvious• provide an auditory message, that says what to

do (which language?)• provide a big label next to the card reader that

flashes when someone enters

• make relevant parts visible• make what has to be done obvious


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Feedback

• Sending information back to the user about what has been done

• Includes sound, highlighting, animation and combinations of these

– e.g. when screen button clicked on provides sound or red highlight feedback:

“ccclichhk”


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Constraints

• Restricting the possible actions that can be performed

• Helps prevent user from selecting incorrect options

• Physical objects can be designed to constrain things– e.g. only one way you can insert a key into a lock


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Logical or ambiguous design?

From: www.baddesigns.com

• Where do you plug the mouse?

• Where do you plug the keyboard?

• top or bottom connector?

• Do the color coded icons help?


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How to design them more logically

(i) A provides direct adjacent mapping between icon and connector

(ii) B provides color coding to associate the connectors with the labels

From: www.baddesigns.com


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Consistency

• Design interfaces to have similar operations and use similar elements for similar tasks

• For example:– always use ctrl key plus first initial of the

command for an operation – ctrl+C, ctrl+S, ctrl+O

• Main benefit is consistent interfaces are easier to learn and use


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When consistency breaks down

• What happens if there is more than one command starting with the same letter?– e.g. save, spelling, select, style

• Have to find other initials or combinations of keys, thereby breaking the consistency rule– e.g. ctrl+S, ctrl+Sp, ctrl+shift+L

• Increases learning burden on user, making them more prone to errors


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Affordances: to give a clue

• Refers to an attribute of an object that allows people to know how to use it– e.g. a mouse button invites pushing, a door handle

affords pulling

• Norman (1988) used the term to discuss the design of everyday objects

• Since has been much popularised in interaction design to discuss how to design interface objects– e.g. scrollbars to afford moving up and down, icons to

afford clicking on


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What does ‘affordance’ have to offer interaction design?

• Interfaces are virtual and do not have affordances like physical objects

• Norman argues it does not make sense to talk about interfaces in terms of ‘real’ affordances

• Instead interfaces are better conceptualized as ‘perceived’ affordances– Learned conventions of arbitrary mappings between

action and effect at the interface– Some mappings are better than others


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Activity

– Physical affordances: How do the following physical objects afford?

Are they obvious?


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Gulfs of execution and evaluation

• The ‘gulfs’ explicate the gaps that exist between the user and the interface

• The gulf of execution – the distance from the user to the physical system

• The gulf of evaluation – the distance from the physical system to the user

• Bridging the gulfs can reduce cognitive effort required to perform tasks


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Bridging the gulfs


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Ergonomics

• Ergonomics is about designing for people, wherever they interact with products, systems or processes.

• ensure that designs complement the strengths and abilities of people and minimize the effects of their limitations, rather than forcing them to adapt.

• Qualified ergonomists are the only recognized professionals to have competency in optimizing performance, safety and comfort.


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Summary (Key points)

• Cognition involves several processes including attention, memory, perception and learning.

• The way an interface is designed can greatly affect how well users can perceive, attend, learn and remember how to do their tasks.

• Theoretical frameworks, such as mental models and external cognition, provide ways of understanding how and why people interact with products.

• This can lead to thinking about how to design better products.