Hci unit 2(3rd final) (2)

Human Computer Interaction
(INSY4112)
12/18/2021 Prepared by Meseret Hailu, 2021 1

Human in HCI

• Information input/output
• Memory
Reasoning, problem solving skill and error
Emotion
Individual difference

➢ To describe input output channels
➢ To recognize memory as part of model of the human as an
information-processing system.
➢ To identify the three types of memory or memory function
➢ To describe how information finds its way into and out of the
human system and how it is processed, manipulated and stored
➢ To consider emotion in build interfaces that promote positive
responses of users in using computer based systems
➢ To take into account individual differences in the designing
process of interfaces 4
Objectives
12/18/2021 Prepared by Meseret Hailu, 2021

❖ Activity 2:
➢ Discuses the five major senses of human beings:
sight, hearing, touch, taste and smell.
➢ Compare these senses analogues to the activities of
computer
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Human in HCI

❖ Introduction
➢ In this chapter,
✓ First look at the human’s input–output channels, the senses and
responders or effectors.
✓ Secondly, we will consider human memory and how it works.
✓ Thirdly, we think about how humans perform complex problem
solving, how they learn and acquire skills, and why they make
mistakes.
✓ Finally, we will discuss how these things can help us in the design
of computer systems. 6
Human in HCI

➢ Human
❖ The human, the user is the central character in any discussion
of interactive systems.
❖ The human is, after all, the one whom computer systems are
designed to assist.
❖ The requirements of the user should therefore be our first
priority.
❖ In order to design something for human beings , we need to
understand their capabilities and limitations.
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Human in HCI

➢ Human
❖ We will look at aspects of cognitive psychology which have a
bearing on the use of computer systems:
✓ how humans perceive the world around them,
✓ how they store and process information and solve
problems, and
✓ how they physically manipulate objects.
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Human in HCI

❖ A person’s interaction with the outside world occurs through
information being received and sent: input and output.
❖ In an interaction with a computer the user receives
information that is output by the computer, and responds by
providing input to the computer. The user’s output becomes
the computer’s input and vice versa.
❖ Input in the human occurs mainly through the senses and
output through the motor control of the effectors.
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2.1. Information input/output

❖ There are five major senses: sight, hearing, touch, taste and smell.
❖ Of these, the first three are the most important to HCI. Taste and smell
do not currently play a significant role in HCI,
 How we make ‘sense’ of the world around us… inputs and
understanding
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The Human as an
Input Device

❖ In the interaction with the computer, the fingers play the primary role,
through typing or mouse control, with some use of voice, eye, head and
body position.
❖ The application you are using has a graphical interface, with menus,
icons and windows.
❖ In your interaction with this system you receive information primarily
by sight, from what appears on the screen.
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❖ However, you may also receive information by ear: for example, the
computer may ‘beep’ at you if you make a mistake or to draw attention
to something, or there may be a voice commentary in a multimedia
presentation.
❖ Touch plays a part too in that you will feel the keys moving (also
hearing the ‘click’) or the orientation of the mouse, which provides
vital feedback about what you have done.
❖ You yourself send information to the computer using your hands, either
by hitting keys or moving the mouse.
12

➢ Vision
❖ Human vision is a highly complex activity with a range of physical
and perceptual limitations, yet it is the primary source of information
for the average person.
❖ We can roughly divide visual perception into two stages:
✓ the physical reception of the stimulus from the outside world, and
✓ the processing and interpretation of that stimulus.
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➢ Vision
❖ On the one hand the physical properties of the eye and the visual
system mean that there are certain things that cannot be seen by the
human;
❖ On the other the interpretative capabilities of visual processing allow
images to be constructed from incomplete information.
❖ We need to understand both stages as both influence what can and
cannot be perceived visually by a human being, which in turn directly
affects the way that we design computer systems.
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➢ Vision
❖ Vision begins with light. The eye is a mechanism for receiving light
and transforming it into electrical energy.
❖ Light is reflected from objects in the world and their image is focused
upside down on the back of the eye.
❖ The receptors in the eye transform it into electrical signals which are
passed to the brain.
15

❖ The human eye has a number of important components as in the
figure below.
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➢ Vision
❖ The cornea and lens at the front of the eye focus the light into a sharp
image on the back of the eye, the retina.
❖ The retina is light sensitive and contains two types of photoreceptor:
rods and cones.
❖ Rods are highly sensitive to light and therefore allow us to see under a
low level of illumination. However, they are unable to resolve fine
detail and are subject to light saturation.
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➢ Vision
❖ This is the reason for the temporary blindness we get when moving
from a darkened room into sunlight:
✓ The rods have been active and are saturated by the sudden light.
✓ The cones do not operate either as they are suppressed by the rods.
✓ we are therefore temporarily unable to see at all.
✓ There are approximately 120 million rods per eye which are
mainly situated towards the edges of the retina.
✓ Rods therefore dominate peripheral vision.
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➢ Vision
❖ Cones are the second type of receptor in the eye.
❖ They are less sensitive to light than the rods and can therefore tolerate
more light.
❖ There are three types of cone, each sensitive to a different wavelength
of light. This allows color vision.
❖ The eye has approximately 6 million cones, mainly concentrated on
the fovea, a small area of the retina on which images are fixated.
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➢ Vision
❖ Understanding the basic construction of the eye goes some way to
explaining the physical mechanisms of vision but visual perception is
more than this.
❖ We will consider some of the capabilities and limitations of visual
processing by looking at little more closely at how we perceive size
and depth, brightness and color, each of which is crucial to the design
of effective visual interfaces.
20

➢ Vision
❖ The information received by the visual apparatus must be filtered
and passed to processing elements which allow us to recognize
coherent scenes, disambiguate relative distances and
differentiate color.
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➢ Vision
❑ Interpreting the signal
1. Perceiving size and depth
❖ How does the eye perceive size, depth and relative distances?
❖ To understand this we must consider how the image appears on the
retina.
❖ The size of that image is specified as a visual angle and perception of
depth
❖ Visual angle affected by both the size of the object and its distance
from the eye. 22

➢ Vision
1. Perceiving size and depth Contd…
❖ Visual angle indicates how much of view object occupies (relates to
size and distance from eye)
❖ Visual acuity is ability to perceive detail (limited)
❖ Familiar objects perceived as constant size (in spite of changes in
visual angle when far away)
❖ Cues like overlapping help perception of size and depth
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Visual angle

➢ Vision
❖ Therefore if two objects are at the same distance, the larger one will
have the larger visual angle.
❖ Similarly, if two objects of the same size are placed at different
distances from the eye, the furthest one will have the smaller visual
angle
❖ If we expect an object to be of a certain size then we can judge its
distance accordingly.
25

➢ Vision
2. Perceiving brightness Contd…
❖ Brightness is in fact a subjective reaction to levels of light.
❖ It is affected by luminance which is the amount of light emitted by an
object.
❖ The luminance of an object is dependent on the amount of light falling
on the object’s surface and its reflective properties.
❖ Luminance is a physical characteristic and can be measured using a
photometer.
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➢ Vision
2. Perceiving brightness Contd…
❖ Contrast is related to luminance:
❖ it is a function of the luminance of an object and the luminance of its
background.
❖ Although brightness is a subjective response, it can be described in
terms of the amount of luminance that gives a just noticeable difference
in brightness
❖ However, the visual system itself also compensates for changes in
brightness. 27

➢ Vision
3. Perceiving color
❖ Color is usually regarded as being made up of three components:
hue(tone), intensity(strength) and saturation (diffusion ).
❖ Hue is determined by the spectral wavelength of the light. Blues have
short wavelengths, greens medium and reds long. Approximately 150
different hues can be discriminated by the average person.
❖ Intensity is the brightness of the color, and
❖ saturation is the amount of whiteness in the color. By varying these
two, we can perceive in the region of 7 million different colors. 28

➢ Vision
3. Perceiving color contd…
❖ The eye perceives color because the cones are sensitive to light of
different wavelengths.
❖ There are three different types of cone, each sensitive to a different
color(blue, green and red).
❖ we should remember that around 8% of males and 1% of females suffer
from color blindness, most commonly being unable to discriminate
between red and green.
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➢ Vision
3. Perceiving Colo Contd… r
❖ Optical illusions highlight the differences between the way things are and
the way we perceive them and in interface design we need to be aware
that we will not always perceive things exactly as they are.
❖ The way that objects are composed together will affect the way we
perceive them, and we do not perceive geometric shapes exactly as they
are drawn.
❖ So far we have concentrated on the perception of images in general.
However, the perception and processing of text is a special case that is
important to interface design, which invariably requires some textual
display. 30

➢ Vision
❖ However, in reading, the perception and processing of text is a special
case that is important to interface design, which invariably requires
some textual display.
❖ There are several stages in the reading process.
✓First, the visual pattern of the word on the page is perceived.
✓It is then decoded with reference to an internal representation of language.
✓The final stages of language processing include syntactic and semantic
analysis and operate on phrases or sentences.
31

➢ Hearing
❖ The sense of hearing is often considered secondary to sight.
➢ The human ear
❖ Just as vision begins with light, hearing begins with vibrations in the
air or sound waves.
❖ The ear receives these vibrations and transmits them, through various
stages, to the auditory nerves.
❖ sound changes or vibrates in air pressure. It has a number of
characteristics which we can differentiate.
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➢ Hearing
➢ Hearing provides information about environment: distances, directions,
objects etc.
❖ Physical apparatus:
outer ear – >protects inner and amplifies sound
middle ear –>transmits sound waves as vibrations to inner ear
inner ear – > chemical transmitters are released and cause impulses in
auditory nerve
❖ Sound
– Pitch –> sound frequency
– loudness –> amplitude
– timbre –> type or quality 33

➢ Hearing
❖ Sound can convey a remarkable amount of information. It is rarely
used to its potential in interface design, usually being confined to
warning sounds and notifications.
❖ The exception is multimedia, which may include music, voice
commentary and sound effects.
❖ However, the ear can differentiate quite subtle sound changes and can
recognize familiar sounds without concentrating attention on the sound
source. This suggests that sound could be used more extensively in
interface design, to convey information about the system state.
34

➢ Hearing
❖ Speech sounds can obviously be used to convey information. This is
useful not only for the visually impaired but also for any application
where the user’s attention has to be divided (for example, power plant
control, flight control, etc.).
❖ Uses of non-speech sounds include the following:
❖ Attention – to attract the user’s attention to a critical situation or to the end of a
process,
❖ Status information – continuous background sounds can be used to convey status
information. For example, monitoring the progress of a process (without the need
for visual attention). 35

➢ Hearing
❖ Confirmation – a sound associated with an action to confirm that
the action has been carried out. For example, associating a sound with
deleting a file.
❖ Navigation – using changing sound to indicate where the user is in a
system. For example, what about sound to support navigation in
hypertext?
❖ Humans can hear frequencies from 20Hz to 15kHz.
❖ Auditory system filters sounds
▪ can attend to sounds over background noise.
▪ for example, the cocktail party phenomenon.
36

➢Touch
❖ The third and last of the senses that we will consider is touch or
haptic perception.
❖ Touch provides us with vital information about our environment.
❖ It tells us when we touch something hot or cold, and can therefore act
as a warning.
❖ It also provides us with feedback when we attempt to lift an object
❖ The apparatus of touch differs from that of sight and hearing in that it
is not localized.
37

➢Touch
❖ We receive stimuli through the skin. Provides important feedback about
environment.
❖ May be key sense for someone who is visually impaired.
❖ The skin contains three types stimulus via receptors of sensory receptor:
❖ Thermo-receptors =>respond to heat and cold,
❖ nociceptors =>respond to intense pressure, heat and pain, and
❖ mechanoreceptors =>respond to pressure.
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➢Touch
❖ Some areas more sensitive than others e.g. fingers.
❖ Kinethesis - awareness of body position, affects comfort and
performance
39

❖ Activity 3
❖ Discuss about smell as major senses and compare this sense in the
activity of computer.
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Human in HCI

➢ Movement
❖ Before leaving this section on the human’s input–output channels, we
need to consider motor control and how the way we move affects our
interaction with computers.
❖ A simple action such as hitting a button in response to a question
involves a number of processing stages.
❖ The stimulus (of the question) is received through the sensory
receptors and transmitted to the brain.
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➢ Movement
❖ The question is processed and a valid response generated.
❖ The brain then tells the appropriate muscles to respond.
❖ Each of these stages takes time, which can be roughly divided into
reaction time and movement time.
❖ Speed and accuracy of movement are important considerations in the
design of interactive systems
42
Time taken to respond to stimulus= reaction time + movement time

➢ Movement
❖ 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 operator
but not in the skilled operator.
43

➢ Movement
❖ Reaction time - dependent on stimulus type:
❖ Fitts' Law describes the time taken to hit a screen target:
Mt = a + b log2(D/S + 1)
where:
✓ a and b are empirically determined constants
✓ Mt is movement time
✓ D is Distance
✓ S is Size of target
 targets as large as possible distances as small as possible
❖ It is the last of these that we are concerned with in relation to human–computer
interaction in relation to input/output.
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➢ Summary
❖ An interaction technique is the fusion of input and output, consisting
of all hardware and software elements, that provides a way for the user
to accomplish a low-level task.
❖ The fundamental task of human-computer interaction is to shuttle
information between the brain of the user and the silicon world of the
computer.
❖ Progress in this area attempts to increase the useful bandwidth across
that interface by seeking faster, more natural, and more convenient
means for users to transmit information to computers,
45

➢ Summary
❖ as well as efficient, salient, and pleasant mechanisms to provide
feedback to the user.
❖ On the user’s side of the communication channel, interaction is
constrained by the nature of human attention, cognition, and
perceptual-motor skills and abilities;
❖ On the computer side, it is constrained only by the technologies and
methods that we can invent.
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➢ Summary
❖ It then attempts to find the common ground through which the two
can be related by studying new modes of communication that could
be used for human-computer interaction (HCI) and developing
devices and techniques to use such modes.
✓ A sensor – e.g.. Eye, skin, ear etc
✓ A process – nerves, electricity etc
✓ Limitations – pitch, brightness etc ….. And there is the added
complexity of individual differences in sensory perception
47

➢ Summary
❖ The communication between the user and the system. Their
interaction framework has four parts:
48

➢ Human Memory
❖ Humans have the capacity to remember and retrieve
information…this affects the way they use technology.
❖ Memory is the second part of our model of the human as an
information-processing system.
❖ Much of our everyday activity relies on memory. As well as storing
all our factual knowledge, our memory contains our knowledge of
actions or procedures.
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2.2. Human Memory

➢ Human Memory Contd…
A model of the structure of memory
❖ It allows us to repeat actions, to use language, and to use new
information received via our senses.
❖ It also gives us our sense of identity, by preserving information from our
past experiences. 50
2.2. Human Memory

❖ We need to understand the capabilities and limitations of the human
memory in order to design our interactive systems in such a way that it
will not overload user's abilities.
❖ In this unit we will answer the following questions :
✓How does our memory work?
✓How do we remember arbitrary lists such as those generated in the
memory game?
✓Why do some people remember more easily than others? and what
happens when we forget? 51
2.2. Human Memory

❖ Memory is associated with each level of processing. We will consider
the way in which memory is structured and the activities that take place
within the system.
❖ There are three types of memory or memory function:
✓sensory buffers,
✓short-term memory or working memory, and
✓Long-term memory.
52
2.2. Human Memory

1. sensory buffers,
❖ Momentary stores for stimuli received by the senses.
❖ This information, unless encoded in the short term memory, is quickly
lost.
❖ Information is transmitted through stimuli into our brain.
❖ The sensory memories act as buffers or collector for stimuli received
through the senses: There exists a sensory memory for each sensory
channel.
✓Iconic memory for visual stimuli,
✓echoic memory for aural stimuli and
✓haptic memory for touch or tactile( tangible) stimuli. 53
2.2. Human Memory

i. Iconic memory
❖ We can demonstrate the existence of iconic memory by moving a finger in
front of the eye. Can you see it in more than one place at once? This
indicates a persistence of the image after the stimulus has been removed. A
similar effect is noticed most vividly at firework displays where moving
sparklers leave a persistent image.
❖ Information remains in iconic memory very briefly, in the order of 0.5
seconds.
54
2.2. Human Memory

ii. Echoic memory
❖ Similarly, the existence of echoic memory is evidenced by our ability to
ascertain the direction from which a sound originates.
❖ This is due to information being received by both ears.
❖ However, since this information is received at different times, we must store
the stimulus in the meantime.
❖ Echoic memory allows brief ‘play-back’ of information. Have you ever had
someone ask you a question when you are reading? You ask them to repeat
the question, only to realize that you know what was asked after all. This
experience, too, is evidence of the existence of echoic memory. 55
2.2. Human Memory

❖ If the information that we received pass to the short term memory depends
on attention.
❖ Attention is the concentration of the mind on one out of a number of
competing stimuli or thoughts.
❖ It is clear that we are able to focus our attention selectively, choosing to
attend to one thing rather than another.
❖ This is due to the limited capacity of our sensory and mental processes.
Information received by sensory memories is quickly passed into a more
permanent memory store, or overwritten and lost.
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2.2. Human Memory

❖ Attention means that we filter the information we got through the stimuli
by arousal. Whereas arousal means the level of interest or need we have.
The arousal is an individual factor.
❖ Every human has a different interest and different needs. The information
will then be stored. If it didn't fit our arousal then it will be overwritten by
new incoming information.
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2.2. Human Memory

2. short-term memory or working memory,
❖ Short-term memory or working memory acts as a ‘scratch-pad’ for
temporary recall of information. It is used to store information which is
only required briefly.
For example,
❖ Calculate the multiplication 35 * 6 in your head.
❖ The chances are that you will have done this calculation in stages,
perhaps 5 × 6 and then 30 × 6 and added the results;
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2.2. Human Memory

❖ Or to calculate the multiplication 35 * 6
❖ You may have used the fact that 6 = 2 × 3 and calculated 2 × 35 =
70 followed by 3 × 70 and added the results;
❖ To perform calculations such as this we need to store the
intermediate stages for use later.
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2.2. Human Memory

❖ consider reading. In order to comprehend a sentence you need to
hold in your mind the beginning of the sentence as you read the
rest. Both of these tasks use short-term memory.
❖ However, the information decays in seconds (10 – 20 Seconds
Decay Time) as items are displaced by new items coming in.
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2.2. Human Memory

❖ There are two basic methods for measuring memory capacity.
❖ The first involves determining the length of a sequence which can
be remembered in order.
❖ The second allows items to be freely recalled in any order.
❖ Using the first measure, the average person can remember 7 ± 2
digits.
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2.2. Human Memory

❖ Example
i). 265397620853 . Now write down as much of the sequence as you
can remember. Did you get it all right? If not, how many digits
could you remember? If you remembered between five and nine
digits your digit span is average.
ii). 44 113 245 8920(Did you recall that more easily?) Here the digits
are grouped or chunked, form of a UK telephone number which
makes it easier to remember. Therefore chunking information can
increase the short-term memory capacity.
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2.2. Human Memory

❖ When we looked at short-term memory, we noted the general rule
that people can hold 7 ± 2 items or chunks of information in short-
term memory. It is a principle that people tend to remember but it
can be misapplied.
❖ For example, it is often suggested that this means that lists, menus
and other groups of items should be designed to be no more than 7
items long.
63
2.2. Human Memory

❖ But use of menus and lists of course has little to do with short-term
memory – they are available in the environment as cues and so do
not need to be remembered.
❖ On the other hand the 7 ± 2 rule would apply in command line
interfaces.
❖ Imagine a scenario where a UNIX user looks up a command in the
manual.
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2.2. Human Memory

❖ Perhaps the command has a number of parameters of options, to be
applied in a particular order, and it is going to be applied to several
files that have long path names.
❖ The user then has to hold the command, its parameters and the file
path names in short term memory while he types them in.
❖ Here we could say that the task may cause problems if the number
of items or chunks in the command line string is more than 7.
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2.2. Human Memory

❖ Perhaps the command has a number of parameters of options, to be
applied in a particular order, and it is going to be applied to several
files that have long path names.
❖ The user then has to hold the command, its parameters and the file
path names in short term memory while he types them in.
❖ Here we could say that the task may cause problems if the number
of items or chunks in the command line string is more than 7.
66
2.2. Human Memory

3. Long-term memory
❖ Long-term memory is our main resource where we store:
▪ Factual information,
▪ Experiential knowledge,
▪ Procedural rules of behavior, everything that we ‘know’.
❖ Long-term memory is characterized by huge capacity, slow access
time and relative accuracy over time
67
2.2. Human Memory

3. Long-term memory
❖ It differs from short-term memory in a number of significant ways:
▪ First, it has a huge, if not unlimited, capacity.
▪ Secondly, it has a relatively slow access time of approximately a tenth
of a second.
▪ Thirdly, forgetting occurs more slowly in long-term memory, if at all.
❖ These distinctions provide further evidence of a memory structure with
several parts.
68
2.2. Human Memory

3. Long-term memory
❖ Long-term memory is intended for the long-term storage of information.
❖ Information is placed there from working memory through rehearsal.
❖ Unlike working memory there is little decay: long-term recall after
minutes is the same as that after hours or days.
❖ Long-term memory structure
❖ There are two types of long-term memory:
❖ Episodic memory and semantic memory.
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2.2. Human Memory

3. Long-term memory
❖ Episodic memory represents our memory of events and experiences in a
sequential order or serial form. It is from this memory that we can
reconstruct the actual events that took place at a given point in our lives.
❖ Semantic memory, on the other hand, is a structured record of facts,
concepts and skills that we have acquired. The information in semantic
memory is derived from that in our episodic memory, such that we can
learn new facts or concepts from our experiences.
70
2.2. Human Memory

3. Long-term memory
❖ Semantic memory is structured in some way to allow access to
information, representation of relationships between pieces of
information, and inference. One model for the way in which semantic
memory is structured and it is as a network.
❖ As an example, our knowledge about dogs may be stored in a network
such as that shown in the figure below
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2.2. Human Memory

Long-term memory may store information in a semantic network
72
2.2. Human Memory

❖ To model the representation of more complex objects or events, structured
representations such as frames and scripts organize information into data
structures.
❖ Slots in these structures allow attribute values to be added. Frame slots
may contain default, fixed or variable information.
❖ A frame is instantiated when the slots are filled with appropriate values.
❖ Frames and scripts can be linked together in networks to represent
hierarchical structured knowledge.
73
2.2. Human Memory

A frame-based representation of knowledge
❖ A script represents this default or stereotypical information, allowing us to
interpret partial descriptions or cues fully.
❖
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2.2. Human Memory

❖ A script comprises a number of elements, which, like slots, can be filled
with appropriate information
A script for visiting the vet
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2.2. Human Memory

❖ A final type of knowledge representation which we hold in memory is the
representation of procedural knowledge, our knowledge of how to do
something.
❖ A common model for this is the production system. Condition–action
rules are stored in long-term memory.
❖ Information coming into short-term memory can match a condition in one
of these rules and result in the action being executed.
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2.2. Human Memory

❖ For example, a pair of production rules might be
❖ IF dog is wagging tail
❖ THEN pat dog
❖ IF dog is growling
❖ THEN run away
77
2.2. Human Memory

➢ LTM Processes
❖ There are three main activities related to long-term memory:
▪ storage or remembering of information,
▪ forgetting and
▪ information retrieval.
78
2.2. Human Memory

a) LTM - Storage of information
❖ How does information get into long-term memory? and how can we improve
this process?
i. Rehearsal
▪ information moves from STM to LTM.
▪ The repeated exposure to a stimulus or the rehearsal of a piece of
information transfers it into long-term memory.
ii. Total time hypothesis
▪ amount retained proportional to rehearsal time.
▪ the amount learned was directly proportional to the amount of time
spent learning.
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2.2. Human Memory

a) LTM - Storage of information
iii. Distribution of practice effect
▪ optimized by spreading learning over time.
▪ learning time is most effective if it is distributed over time
iv.Structure, meaning and familiarity
▪ Information easier to remember.
▪ If information is not meaningful it is more difficult to
remember.
▪ if information is meaningful and familiar, it can be related to
existing structures and more easily incorporated into memory.
80
2.2. Human Memory

b) LTM - Forgetting
i. Decay
▪ information is lost gradually but very slowly
ii. Interference
▪ new information replaces old: retroactive interference
▪ old may interfere with new: proactive inhibition
▪ so may not forget at all memory is selective and affected by
emotion – can subconsciously `choose' to forget
81
2.2. Human Memory

c) LTM - retrieval
i. Recall
▪ information reproduced from memory can be assisted by
signals , e.g. categories, imagery
ii. Recognition
▪ information gives knowledge that it has been seen before
▪ less complex than recall - information is cue
82
2.2. Human Memory

c) LTM - retrieval
i. Recall
▪ information reproduced from memory can be assisted by
signals , e.g. categories, imagery
ii. Recognition
▪ information gives knowledge that it has been seen before
▪ less complex than recall - information is cue
83
2.2. Human Memory

➢Reasoning, problem solving, skill and error
❖ Now let's look at how information is processed and manipulated in
human being's mind.
❖ Human thought is conscious and self-aware: while we may not
always be able to identify the processes we use, we can identify
the products of these processes, our thoughts.
❖ In addition, we are able to think about things of which we have no
experience, and solve problems which we have never seen before.
How is this done?
84
2.2. Human Thinking

❖ In this section we will consider two categories of thinking:
reasoning and problem solving.
❖ In practice these are not distinct since the activity of solving a
problem may well involve reasoning and vice versa.
❖ However, the distinction is a common one and is helpful in
clarifying the processes involved.
❖ We come to look at how Information is processed and
manipulated.
85
2.2. Human Thinking

❖ This is the area which is most complex and which separates
humans from other information-processing systems, both artificial
and natural.
❖ An important concept from cognitive psychology is the model
human processor (MHP).
86
2.2. Human Thinking

❖ This describes the cognitive process that people go through
between perception and action.
❖ It is important to the study of HCI because cognitive processing
can have a significant effect on performance, including task
completion time, number of errors, and ease of use.
❖ This model was based on the human information-processing
model.
87
2.2. Human Thinking

➢Human Information Processing Model
88
2.2. Human Thinking
Encoding Comparison
Response
selection
Response
execution
Input Response
Attention
Memory

➢ The model human processor consists of three interacting systems. Each has its
own memory and processor.
➢ The model also includes a number of principles of operation which dictate the
behavior of the systems under certain conditions.
➢ This model focuses on internal cognition driven by the cooperation of three
independent units of sensory, cognitive and motor activity where each unit
maintains its own working store of information.
89
2.2. Human Thinking

1. Perceptual processor:- is in a system, handling sensory stimulus from the
outside world, the motor system and the cognitive system,
✓ Outputs into audio storage
✓ Outputs into visual storage
2. Cognitive processor:- provides the processing needed to connect the two
✓ Outputs into working memory.
✓ Has access to: Working memory , Long term memory
3. Motor processor
✓ Carries out actions
90
2.2. Human Thinking

➢ Reasoning
❖ Reasoning is the process by which we use the knowledge we have to draw
conclusions or infer something new about the domain of interest.
❖ There are a number of different types of reasoning: deductive, inductive and
abductive.
1. Deductive Reasoning
❖ It is a reasoning type one starts with a given theory as the basis for which we
develop hypotheses and then confirm these with specific data acquired using
observation or experimentation.
❖ Derive logically necessary conclusion from given premises from general to specific.
❖ Example :
▪ Major premise: All men are mortal
▪ Minor premise: Socrates is a man
▪ Conclusion: Socrates is mortal 91
2.2. Human Thinking

1. Deductive Reasoning
❖ Logical conclusion not necessarily true:
Example
▪ If it is raining then the ground is dry
▪ It is raining
▪ Therefore the ground is dry …. Is incorrect
❖ When truth and logical validity clash …
▪ Some people are babies
▪ Some babies cry
▪ Inference - Some people cry…. Is Correct?
❖ People bring world knowledge to tolerate
92
2.2. Human Thinking

2. Inductive Reasoning
❖ Is the process of establishing general principles from specific observations
❖ Induction is generalizing from cases we have seen to infer information about cases we have
not seen
3. Abductive reasoning
❖ Abduction reasons from a fact to the action or state that caused it.
❖ It is reasoning from event to cause
❖ This is the method we use to derive explanations for the events we observe.
❖ If the event and the action are unrelated, confusion and even error often result.
Example
▪ Sam drives fast when drunk.
▪ If I see Sam driving fast, assume drunk.
❖ Unreliable: can lead to false explanations 93
2.2. Human Thinking

➢ Problem solving
❖ It is the Process of finding solution to unfamiliar task using the knowledge we
have
❖ There are a number of different views of how people solve problems.
1) The earliest Gestalt view that problem solving involves both reuse of
knowledge and insight.
❖ They claimed, problem solving is both productive and reproductive.
▪ Reproductive problem solving draws on previous experience as the behaviorists
claimed, but
▪ Productive problem solving involves insight and restructuring of the problem.
❖ Other experiments observed human problem-solving behavior. One well-known
example of this is Maier’s pendulum problem
94
2.2. Human Thinking

➢ Problem solving
2) Problem space theory: The problem has an initial state and a
goal state and people use the operators to move from the former
to the latter.
▪ Problem space comprises problem states
▪ Problem solving involves generating states using legal state
transition operators
▪ The problem has an initial state and a goal state and people use the
operators to move from the former to the latter.
95
2.2. Human Thinking

➢ Problem solving
2) Problem space theory
▪ Heuristics may be employed to select operators
e.g. means-ends analysis. In means–ends analysis the initial state is
compared with the goal state and an operator chosen to reduce the
difference between the two.
▪ Operates within human information processing system
▪ Largely applied to problem solving in well-defined areas
e.g. puzzles rather than knowledge intensive areas
96
2.2. Human Thinking

➢ Problem solving
3) Analogy in problem solving:- is done by mapping knowledge relating
to a similar known domain to the new problem – called analogical
mapping. Similarities between the known domain and the new one are
noted
▪ Analogical mapping difficult if domains are semantically different.
people often miss analogous information, unless it is semantically
close to the problem domain.
▪ The use of analogy is indicative of the Gestalt view of productive
restructuring and insight. Old knowledge is used to solve a new
problem. 97
2.2. Human Thinking

➢ Problem solving
4) Skill acquisition
▪ Skilled activity characterized by chunking
▪ Conceptual rather than superficial grouping of problems
▪ Information is structured more effectively
98
2.2. Human Thinking

➢ Errors and mental models
❖ Human capability for interpreting and manipulating information is quite
impressive. However, we do make mistakes
❖ Types of error
 slip
▪ 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 99
2.2. Human Thinking

➢ Emotion
❖ Various theories of how emotion works
▪ James-Lange: emotion is our interpretation of a physiological response to a
stimuli
▪ Cannon: emotion is a psychological response to a stimuli
▪ Schacter-Singer: emotion is the result of our evaluation of our physiological
responses, in the light of the whole situation we are in.
❖ Emotion clearly involves both cognitive and physical responses to
stimuli
100
2.2. Human Thinking

➢ Emotion
❖ The biological response to physical stimuli is called affect
❖ Affect influences how we respond to situations
▪ positive → creative problem solving
▪ negative → narrow thinking
❖ As Donald Norman says:
“Negative affect can make it harder to do even easy tasks; positive affect can
make it easier to do difficult tasks”
101
2.2. Human Thinking

➢ Emotion
❖ Implications for interface design
▪ stress will increase the difficulty of problem solving
▪ relaxed users will be more forgiving of shortcomings in design
▪ Aesthetically pleasing and rewarding interfaces will increase positive affect
➢ Individual differences
▪ long term
✓ sex, physical and intellectual abilities
▪ short term
✓ effect of stress or fatigue
▪ changing
✓ age
102
2.2. Human Thinking

❖ So far we have looked briefly at the way in which humans receive,
process and store information, solve problems and acquire skill.
❖ But how can we apply what we have learned to designing interactive
systems? Is an important question.
103
2.2. Human Thinking

Introduction to HCI cont...
Top-down view

Introduction to HCI cont...
The End of Unit Two

Hci unit 2(3rd final) (2)

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