1. 1 Principle of Human Computer Interaction Faculty of Computing and Information Technology King Abdul Aziz University Khalid Al-Omar 1

2. 2 Understanding Human, Computer, and Interaction Lecture 4 2

3. 3 the Human, Computer, Interaction In order to design something for someone, we need to understand the: 1.the Humans – perceive the world around them. – store and process information and solve problems. – physically manipulate objects. 2.the Computer – Technology they going to use 3.the Interaction – How people going to interact to technology 3

4. 4 the human 1.Information Input/Output Channels – visual, auditory, haptic, movement 2.Information stored in memory – sensory, short-term, long-term 1.Users share common capabilities/limitation but are individuals with differences 4

5. 5 Input-Output Channels Five major senses: sight, hearing, touch, taste, and smell. Sight, hearing, and touch are the most important in HCI Receive information from computer Sight Hearing Touch Send information to computer Touch (e.g. mouse), Sight (e.g. eyegaze system (using eyes movement)) 5

6. 6 Input-Output Channels (continue) 1.Vision o Colour o Reading o Optical Illusions 2.Hearing o Sound 3.Touch o Movement 6

7. 7 Vision 1.Colour  Colour blind: is the decreased ability to perceive differences between some of the colors that others can distinguish.  8% males and 1% females colour blind  Red–Green  Blue– There are two major types of color blindness:  Total color blindness (is less common)  Partial color blindness 7 Yellow

8. 8 Partial color blindness Red–Green color blind 8

9. Partial color blindness (continue) – Blue - color blind 9 http://www.colblindor.com/2006/05/08/tritanopia-blue-yellow-color-blindness/ Yellow

10. Total color blindness 10 http://www.colour-blindness.com/variations/total/

11. 11 GUI & color blindness Graphical User Interfaces should be understandable even without colors. 11

12. 12 2. Reading People are able to read at 200 wpm on paper, and 180 wpm on a monitor Reading from computer screen is slower than from a book. – Longer line length – Fewer words to a page 12

13. 13 Reading- lowercase/ UPPERCASE Also, you should know that WORDS WRITTEN IN BLOCK CAPITALS take longer to read than those in lower case. lowercase – easy to read UPPERCASE – Better for individual letters and non-words e.g. flight numbers: BA793 vs. ba793 13

14. 14 3. Optical Illusions 14

15. 15 3. Optical Illusions 15

16. 16 Hearing Provides information about environment: distances, directions, objects etc. Humans can hear frequencies from 20Hz to 15kHz – Human ear can distinguishing frequency changes at low frequency, but is less accurate at high frequencies. Auditory system filters sounds – allowing people to ignore background noise and concentrate on important information. for example, in party 16

17. 17 Hearing People tend to underestimate the amount of information that they receive through their ears. People are selective to their hearing. – For example, if someone says your name People not able to differentiate sound, If sound are too loud or frequencies too similar 17

18. 18 Hearing/Sound Sound used as: – warning or notification – Sound especially used while eyes are busy Types of sound: Speech or non-speech – For example, Non-speech like music Speech sound can be used convey information 18

19. 19 Hearing/Sound Non-speech sound can be used for: 1.Attention For example, end of a process 2.Confirmation For example deleting a file 3.Status information For example, monitoring the progress of a process 19

20. 20 Touch May be key sense for someone who is visually impaired. Stimulus received via receptors in the skin: – heat and cold – Pain and pressure Touch will become more important in the near future Touch become important in shopping online – For example, clothes 20

21. 21 Movement Time taken to respond to stimulus: reaction time + movement time Movement time dependent on age, fitness etc. Reaction time - dependent on stimulus type: – visual~ 200ms – auditory~ 150 ms – pain~ 700ms Increasing reaction time decreases accuracy in the unskilled user but not in the skilled user.

22. 22 Information stored in memory There are three types of memory function: Environment input

23. 23 Sensory memory Buffers for stimuli received through senses – Iconic memory: visual stimuli – Echoic memory: aural stimuli – Haptic memory: tactile stimuli Sensory memory continuously overwritten by new information Information is passed to short-memory by attention

24. 24 Short-term memory (STM) – Rapid access ~ 70ms – Forgetting occur ~ 200ms – limited capacity: the number of objects and chunks of new information an average human can hold in short memory.

25. 25 Short-term memory (STM) – capacity limits can be overcome by 1.Grouping of information into larger meaningful units 2.Individual differences, e.g., chess masters vs. novices 3.Also seen in everyday tasks that must be held in STM

26. 26 Examples 212348278493202 0121 414 2626 HEC ATR ANU PTH ETR EET ‘The cat ran up the tree’

27. 27 Long-term memory (LTM) Stored all our knowledge Slow access ~ 1/10 second Forgetting occur more slowly Huge or unlimited capacity

28. 28 LTM - Storage of information How does information get into LTM? – Rehearsal: information moves from STM to LTM total time hypothesis – Learning amount = Learning time Learning time is most effective if it is distributed over time – optimized by spreading learning over time structure, meaning and familiarity – information easier to remember For example, password should be meaningful to you

29. 29 Errors and mental models Types of error slips – right intention, but failed to do it right – causes: poor physical skill,inattention etc. – change to aspect of skilled behaviour can cause slip mistakes – wrong intention – cause: incorrect understanding humans create mental models to explain behaviour. if wrong (different from actual system) errors can occur

30. 30 Emotion (cont.) emotion influences how we respond to situations – positive  creative problem solving – negative  narrow thinking “Negative affect can make it harder to do even easy tasks; positive affect can make it easier to do difficult tasks” (Donald Norman)

31. 31 Individual differences long term – Gender, physical and intellectual abilities short term – effect of stress Changing through time – age