Human computer interaction-Memory, Reasoning and Problem solving

CS8079-Human Computer
Interaction
Presented by
N. Jagadish kumar
Assistant Professor
Department of Information Technology
Velammal Institute of technology

Unit-1 Foundation of HCI
Session-3
• The Human – Memory – Reasoning & Problem
solving

Definition
• Memory is our ability to encode, store, retain
and subsequently recall information and past
experiences in the human brain.
• It can be thought of in general terms as the
use of past experience to affect or influence
current behavior.

Structure of memory
• Much of our day-to-day activities rely on
memory.
• Apart from storing information, it contains our
knowledge of actions or procedures.

….
It is generally agreed that there are three types of
memory or memory function:
• sensory buffers
• short-term memory or working memory
• long-term memory
These memories interact, with information being
processed and passed between memory stores.

Sensory Memory
• The sensory memories act as buffers for
stimuli received through the senses.
• A sensory memory exists for each sensory
channel:
• iconic memory for visual stimuli
• echoic memory for aural stimuli
• haptic memory for touch

…..
• These memories are constantly overwritten by
new information coming in on these channels.
• Example for the existence of Iconic memory.
• ﬁrework displays where moving sparklers
leave a persistent image.
• Information remains in iconic memory very
brieﬂy, in the order of 0.5 seconds.

….
• Example for the existence of echoic memory
is evidenced by our ability to ascertain the
direction from which a sound originates.
• Example when some ask to you when your
reading? You ask them to repeat the question.
only to realize that you know what was asked
after all.

….
• Information is passed from sensory memory
to short-term memory by attention, thereby
ﬁltering the stimuli to only those which are of
interest at a given time.
• Attention is the concentration of the mind on
one out of a number of competing stimuli or
thoughts.

Short term memory
• For example, calculate the multiplication 35 × 6 in your
head.
• The chances are that you will have done this
calculation in stages
stage1 : 5 × 6 =30
stage 2: 30 × 6=180
Stage 3: 30+180= 210
To perform calculations such as this we need to store
the intermediate stages for use later

….
• Short-term memory can be accessed rapidly,
in the order of 70 ms.
• However information can only be held there
temporarily, in the order of 200 ms.

…
• 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.

….
• Look at the following number sequence:
265397620853
• Now write down as much of the sequence as
you can remember.
• How many digits could you remember? If you
remembered between ﬁve and nine digits
your digit span is average.

…
• Now try the following sequence:
44 113 245 8920
• Here the digits are grouped or chunked.
Therefore chunking information can increase the
short-term memory capacity.
• The successful formation of a chunk is known as
closure
• This process can be generalized to account for
the desire to complete or close tasks held in
short-term memory…….

Human computer interaction-Memory, Reasoning and Problem solving

Experiment to recall Sequence of
words
• Most people would have difficulty
remembering the following sequence of
chunks:
• HEC ATR ANU PTH ETR EET
• However, if you notice that by moving the last
character to the ﬁrst position, you get the
statement ‘the cat ran up the tree’ the
sequence is easy to recall.

..
• In experiments where subjects were able to
recall words freely, evidence shows that recall
of the last words presented is better than
recall of those in the middle . This is known as
the recency effect.

Long Term Memory
• long-term memory is our main resource.
• Here we store factual information,
experiential knowledge, procedural rules of
behavior – in fact, everything that we ‘know’.
• First, it has a huge, unlimited, capacity of
memory.
• Secondly, it has a relatively slow access time
from the memory.
• Thirdly, forgetting occurs more slowly in long-
term memory

….
• Long-term memory is intended for the long-
term storage of information.
• 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:
1.episodic memory
2. semantic memory.

Episodic memory
• Episodic memory : involves the recollection of
specific events, situations, and experiences.
Your memories of
• your first day of school
• attending a friend's birthday party
• your brother's graduation are
all examples of episodic memories.

Semantic memory
• Semantic memory refers to general world
knowledge that we have accumulated
throughout our lives.
• For example, knowing that football is a sport
is an example of semantic memory

our knowledge about dogs may be stored in a
network
Semantic networks represent the associations and relationships between
single items in memory

Structured Representation-Frames

Structured Representation -Scripts

….
• 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.
• Frames and scripts can be linked together in
networks to represent hierarchical structured
knowledge.

…
• A script comprises a number of elements, which, like
slots, can be ﬁlled with appropriate information:
• Entry conditions Conditions that must be satisﬁed for
the script to be activated.
• Result Conditions that will be true after the script is
terminated.
• Props Objects involved in the events described in the
script.
• Roles Actions performed by particular participants.
• Scenes The sequences of events that occur.
• Tracks A variation on the general pattern representing
an alternative scenario

Exercise
• Complete the frame representation of the
figure below:

Long Term memory process
• There are three main activities related to long-
term memory:
1.storage or remembering of information
2.forgetting
3 information retrieval

….
• Information from short-term memory is
stored in long-term memory by rehearsal.
• The repeated exposure to a stimulus or the
rehearsal of a piece of information transfers it
into long-term memory.

…
• This process can be optimized in no of ways.
• Total time hypothesis – According to Ebbinghaus.
He discovered that the amount learned was
directly proportional to the amount of time spent
learning.
• Distribution of practice effect- According to
Baddeley . learning time is most effective if it is
distributed over time.
• Example: training period was divided into weekly
sessions of one hour performed better than
those who spent two or four hours a week
learning

Long-term memory processes
• Theories of Forgetting
– Decay
– Interference
• Decay:The first theory suggests that the information held
in long-term memory may eventually be forgotten.
• Jost’s law, which follows from this, states that if two memory traces
are equally strong at a given time the older one will be more
durable.
• Interference: The second theory is that information is lost
from memory through interference.

Long-term memory processes
Retroactive interference
• If we acquire new information it causes the loss of old
information.
• Example : If you change telephone numbers, learning your
new number makes it more difficult to remember your old
number. This is because the new association masks the old.
Proactive Inhibition
• Sometimes the old memory trace breaks through and
interferes with new information.
• Example : When you find yourself driving to your old house
rather than your new one.

Information Retrieval
• Two types
– Recall
– Recognition
• Recall: the information is reproduced from memory.
– Recall can be assisted by the provision of retrieval cues, which enable
the subject quickly to access the information in memory.
– One such cue is the use of categories.
• Recognition: the presentation of the information provides the
knowledge that the information has been seen before.
– Recognition is the less complex cognitive activity since the
information is provided as a cue.

So far we discussed about how information
ﬁnds its way into and out of the human system
and how it is stored.

THINKING: REASONING AND PROBLEM
SOLVING
• Finally here we come to look at how it is
processed and manipulated.
• This is perhaps the area which is most
complex and which separates humans from
other information-processing systems, both
artiﬁcial and natural.

…
• Animals can receive and store information.
• Artificial intelligence machines can receive and
store information.
• But their ability to use that information is
limited when compares to human.
• Humans have the ability to use the
information they stored for reasoning &
Problem solving

Humans
solve problems which we have never
seen before.
able to think about things of which we
have no experience
Conscious and Self- aware
Able to use information to reason and
solve problems
04
03
02
01

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
• abductive.

Inductive Reasoning
• Induction is generalizing from cases we have seen to infer
information about cases we have not seen.
Example 1:
The coin I pulled from the bag is a penny.
That coin is a penny.
A third coin from the bag is a penny.
Therefore, all the coins in the bag are pennies.
Example 2: conclusion does not follow logically from the
statements.
Harold is a grandfather.
Harold is bald.
Therefore, all grandfathers are bald

Inductive Reasoning
Given a cause and an effect, induce a rule.
Example : You can induce that the soup is tasty
if you observe all of your friends consuming it.

Inductive Reasoning
Check whether the mangoes are ripe or raw?

Deductive Reasoning
Given the rule and the cause, deduce the effect

Deductive Reasoning
Deductive reasoning derives the logically necessary
conclusion from the given premises.
Example 1 – Derive logically necessary conclusions
If it is Friday then she will go to work
It is Friday
Therefore she will go to work.
Example 2 – Not necessarily be True
If it is raining then the ground is dry
It is raining
Therefore the ground is dry.

Deductive Reasoning
• Often misapplied…
Some people are babies
Some babies cry
>> Some people cry??
Invalid deduction, Not told that all babies are
people. Truth and validity clash.
People bring their world knowledge into the
reasoning process

Abductive Reasoning
Given a rule and an effect, abduce a cause.

Abductive Reasoning
• Given a rule and an effect, abduce a cause
• It begins with an incomplete set of observations and
proceeds to the likeliest possible explanation for the set.
• Abductive reasoning yields the kind of daily decision-
making that does its best with the information at hand,
which often is incomplete.
• A medical diagnosis is an application of abductive
reasoning: given this set of symptoms, what is the diagnosis
that would best explain most of them?
• Examples of abductive reasoning include
– A doctor making a diagnosis based on test results
– A jury using evidence to pass judgment on a case: in both
scenarios, there is not a 100% guarantee of correctness—just
the best guess based on the available evidence.

Problem Solving
• If reasoning is a means of inferring new
information from what is already known,
problem solving is the process of finding a
solution to an unfamiliar task, using the
knowledge we have.
• Human problem solving is characterized by the
ability to adapt the information we have to
deal with new situations. However, often
solutions seem to be original and creative.

….
1
• Gestalt View
2
• Problem Space Theory
3
•Analogy in Problem Solving

Gestalt Theory
• Problem Solving is both productive and
reproductive
• Reproductive draws on previous experience
• Productive involves insight and restructuring of
the problem
• Not provide sufficient evidence or structure to
support its theories
• ‘Functional Fixedness’ is a Gestalt term referring
to and when learning or past experience
impedes problem solving

Maier’s Pendulum Problem
• Birch and Rabinowitz (1951) adapted the two-cord problem from Maier
(1930, 1931), where subjects would be given 2 cords hanging from the
ceiling, and 2 heavy objects in the room.
• They are told they must connect the cords, but they are just far enough
apart that one cannot reach the other easily. The solution was to tie one of
the heavy objects to a cord and be a weight, and swing the cord as a
pendulum, catch the rope as it swings while holding on to the other rope,
and then tie them together.
The participants are split into 3 groups:
• Group R, which completes a pretask of completing an electrical circuit by
using a relay
• Group S, which completes the circuit with a switch
• Group C which is the control group given no pretest experience.
Group R participants were more likely to use the switch as the weight, and
Group S were more likely to use the relay. Both groups did so because they
were previous experience led them to use the objects a certain way, and
functional fixedness did not allow them to see the objects as being used for
another purpose.

Insight : Problem solving in monkeys
• Monkeys showed “insight” during problem-solving.
• Demonstrated productive “new way of structuring
elements showing insight and creativity”
• Deep useful understanding of the nature of the
problem versus trial-and-error (a.k.a., reproductive //
tried and true // rule-based) problem solving (e.g., of
the cat-in-the-box of Thorndike, 1898).
• Solved problems by using tools.
• Sultan stacks boxes to reach bananas.

Problem Space Theory
• Generating problem states(initial, goal) using legal
state transition.
• In means–ends analysis the initial state is compared
with the goal state and an operator chosen to reduce
the difference between the two.
• Experience allows us to solve problems more easily
since we can structure the problem space
appropriately and choose operators efficiently.
• In General Problem Solver model the problems may
be unfamiliar but the knowledge that is required to
solve them is present in the statement of the problem
and the expected solution is clear. (Solving Puzzles)

• Moving from start state to end state by
moving one disk at a time, and never placing
a smaller disk on a larger disk
• Goal State (clear)
• Initial State (clear)
• Sub-goals (problem can be broken down)
• Problem Space (all possible legal moves
[operators])

• all possible legal moves
• Each legal move from the initial state to some
intermediate state is specifically defined by
an OPERATOR.

• Goal State, Initial State, Sub-goals, Problem
Space
• All possible legal moves (operator actions)

Analogical Mapping
• One special kind of restructuring, is analogical problem solving.
• To find a solution to one problem - the so called target problem, an
analogous solution to another problem - the source problem, is
presented.
As a doctor you have to treat a patient with a malignant, inoperable
tumor, buried deep inside the body. There exists a special kind of ray,
which is perfectly harmless at a low intensity, but at the sufficient high
intensity is able to destroy the tumor - as well as the healthy tissue on
his way to it. What can be done to avoid the latter?
• Mapping knowledge relating to a similar known domain to the new
problem
• People often miss analogous information, unless it is semantically
close to the problem domain

Analogical Mapping
• A General wanted to capture his enemy's fortress. He
gathered a large army to launch a full-scale direct
attack, but then learned, that all the roads leading
directly towards the fortress were blocked by mines.
These roadblocks were designed in such a way, that it
was possible for small groups of the fortress-owner's
men to pass them safely, but every large group of
men would initially set them off.
• The General divided his troops into several smaller
groups and made each of them march down a
different road, timed in such a way, that the entire
army would reunite exactly when reaching the
fortress and could hit with full strength.

Skill Acquisition
• All of the problem solving that we have
considered so far has concentrated on
handling unfamiliar problems.
• Gain insight into how skilled behavior works,
and how skills are acquired, by considering
the difference between novice and expert
behavior in given domains.

Skill Acquisition
• Backwards Chaining (working backwards)
– working back from the end state until reaching
the origin state. This is common for novice
problem-solvers in the domain (also used by
experts).
• Forwards Chaining (working forwards)
– Experts are much more likely to start from the
origin point and move forward whenever the
problem strikes them as readily solvable.

Skill Acquisition
Chess Playing
• Initial state – Opening board positions
• Goal state - one player checkmating the other
• Operators - To move states are legal moves of chess
DeGroot, Chase and Simon - interesting observations
1) players did not consider large numbers of moves in
choosing their move, nor did they look ahead more than
six moves
2) Masters considered no more alternatives than the less
experienced, but they took less time to make a decision
and produced better moves.

Anderson’s ACT model – General Rule
• Proceduralization
– Mechanism to move from the first to the second. It removes the
parts of the rule which demand memory access and replaces
variables with specific values.
• Generalization
– Mechanism which moves from the second level to the third. It
generalizes from the specific cases to general properties of those
cases.
IF cook[type, ingredients, time]
THEN
cook for: time
cook[casserole, [chicken,carrots,potatoes], 2 hours]
cook[casserole, [beef,dumplings,carrots], 2 hours]
cook[cake, [flour,sugar,butter,eggs], 45 mins]

Anderson’s ACT model -
Proceduralization
IF type is casserole
AND ingredients are [chicken,carrots,potatoes]
THEN
cook for: 2 hours
AND ingredients are [beef,dumplings,carrots]
THEN
cook for: 2 hours
IF type is cake
AND ingredients are [flour,sugar,butter,eggs]
THEN
cook for: 45 mins

Anderson’s ACT model -
Proceduralization
AND ingredients are ANYTHING
THEN
cook for: 2 hours
Anderson's ACT Model
1. Uses knowledge extensively
2. Relies upon known procedures
3. Represents skilled behavior
Experts tend to rehearse their actions mentally. Efficient but
cause errors when the context changes.

Errors and Mental models
• Errors result from changes in the context of
skilled behavior (slip)
• Mental model
– Based on superstition rather than evidence
– Incorrect interpretation of the evidence
– Certain universal convention to interpret the
world. If it is violated, explicit support must be
given to correct mental model
– Incorrect modeling result in error (mistake)

Human computer interaction-Memory, Reasoning and Problem solving

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