Unformatted text preview: CO105 Communication II
Lesson 4 Lesson Practice, Interference and Problem Solving Problem 1 Objectives
• The implication of practice and interference • Introduction to problem solving skills and strategies • Strength and limitation of expertise in solving problems 2 Practice
• What defines a task as "difficult"? When we use the word difficult in this sense, we mean that we need to concentrate more to carry out the task. Different things may be difficult for different people. In general, if you have practiced a certain task a few times, then that task seems easier and requires less concentration. Typing requires much less attention for a professional secretary than a high school freshman. Therefore, that secretary has more attention left to talk on the phone, carry on a conversation, or perform another task at the same time. perform
3 Practice (cont.)
• Practice reduces the demand on processing Practice resources, so it also reduces interference. Tasks that are highly practiced can become automatic. Almost any task can become easy through practice, so over time, you can learn to do almost any two tasks at once. However, it should be emphasized that interference is only reduced, not eliminated; that is, talking on the phone while driving, no matter how often you do it, will still lower the attention you have available for driving.
4 Stroop Task
• Automatic and Practice Automatic • With practice, some activities can become With automatic--combining many actions into one, and so using less attention. Reading is one example of this. Once you have started to read a word, you can't stop in the middle but it doesn’t prevent yourself from reading a word.
5 Stroop Task (cont.)
• Driving is another example; you don't Driving need to consciously think about the movements you make while driving. Automatic actions are completely routine and are generally less affected by interference, suggesting that they take much less attention to carry out than other activities.
6 Interference in the Stroop Task
• One experiment used very often in One psychology experiments by showing a series of words to students one at a time. Each word is printed in a different color of ink. The subject's task is to say the color of the ink as quickly as possible. 7 Stroop effects Peter
8 Stroop effects Mary
9 Stroop effects GREEN
10 Interference in the Stroop Task Interference (cont.) (cont.)
• For words that are not related to color, this For task is relatively easy. However, when the word printed is the name of a color that conflicts with the color of the ink, the response significantly more slowly. Their lower reaction time shows that something is interfering with the color-naming task.
11 Interference in the Stroop Task Interference (cont.) (cont.)
• If they were able to look at the ink color If without reading the word, then there would be no increase in interference, since it doesn’t matter what the word said. • Since their performance is disrupted more Since for color names than for any other words, the experiment provides good evidence that reading is automatic and the processing is immediate. processing
12 Group discussion
• What are the implications for learning What from ‘Practice and Interference’? from 13 Introduction to Problem Solving Introduction
• Humans have amazing intellectual Humans capabilities. We can create solutions for a number of different and complex problems. problems. • What do we know about problem solving? What • shortcuts and educated guessing shortcuts techniques • use tools like rules and assumptions
14 Introduction to Problem Solving (cont.)
• Make assumptions about a problem at the Make start
– can cause mistakes if our assumptions are can violated. violated. – Those assumptions help structure our Those thoughts, – but too much structure can limit our creativity but and make solving problems more difficult. • We will examine the processes involved in We problem solving, including the strategies and shortcuts that make humans so effective. effective. 15 Strategies for Problem Solving
• Problem Space • To solve the problem, you need to travel from a To starting point, called the initial state, to an ending point, called the goal state. • The initial state includes all the knowledge and The resources you currently have available. • The goal state refers to the solution that you The want to reach. • To get from the initial state to the goal state, you To have a number of tools you can use, called operators. The set of possible ways to travel from the initial state to the goal state is called the problem space.
• Solve a problem is to simply mentally test Solve every possible path leading from initial state to goal state. • Process of trial and error considers all Process possible operators available at every step. 17 R O 18 R O OR 19 R O E 20 R O E T 21 R O E T S 22 R O E T S H
23 Generate-and-Test (cont.)
• Generate-and-test is not a realistic Generate-and-test problem-solving method for most complex problems. Instead, we must rely on strategies that consider only a subset of the possibilities. 24 Hill-Climbing Strategy
• You may always take the direction that You toward the goal state. • However, this strategy may fail if the However, correct path winds around and away from the goal state before returning to it later. 25 Hill-Climbing Strategy (cont.)
• In the river-crossing problems, In • the initial state is a number of predators the and prey on one side of the river and a boat with a limited capacity, • the goal state is to have everyone on the the opposite side of the river, • you often must transport beings back to you the original side of the river.
26 Hill-Climbing Strategy (cont.)
• It may seem like they're going in the It wrong direction, but in fact this "downhill" step is necessary to solve the problem. This type of problem is difficult precisely because people are often inclined use the hill-climbing strategy to move toward the goal state. 27 Sub-problems Strategy
• break each problem down into a few subproblems. • When working through complex problems, people When tend to work very quickly at some points and pause at others. • Smaller problems are easier to solve in general Smaller because there are fewer possible paths to consider. 28 Working Backwards
• Some problems are best solved by starting Some at the goal state and working backward toward the initial state. Many people solve mazes this way, because there are generally fewer choices to consider at the end than at the beginning. • This strategy can reduce the overwhelming This number of paths available from the initial state.
29 Reasoning by Analogy
• One method that works for many different One types of problems is ‘reasoning by analogy’. types • The problem-solver uses his knowledge The about previous similar problems to find on the best way to solve the current one. • Use of analogies hinges on familiarity since Use analogies are not helpful without some previous experience with similar problems.
30 Reasoning by Analogy (cont.)
• Analogies are simply patterns in the Analogies structures of problems because experts are more likely to see patterns in problems' structures. • Novices tend to examine the surface Novices aspects of a problem, such as comparing problems with similar aspects, rather than the structural aspects of how the problem is set up.
31 Making Judgments
• Making judgments due to incomplete information. • For example, John wants to get his mother For something nice for her birthday. She probably didn't give him any hint. John needs to guess what his mother prefer based on what he knows about her and gifts for women in general. John will be making a judgment based on inferences from what he already knows. 32 Making Judgments (cont.)
• People rely heavily on shortcuts to save People time when making complex judgments. • It saves time but not always accurate. It • Our judgments are biased by cognitive Our processes that are carried out outside of our awareness. • We will examine some shortcuts and We biases that commonly influence our judgments.
• Judgments often require analysis of the Judgments frequency of some item or event. • To continue the above example, if John To considers buying his mother a pair of slippers, he might considers how often she wears slippers now. wears • The availability of shortcuts makes use of The information that is easily accessible in memory to make judgments about how common items or events are.
34 Availability (cont.)
• Are there more English words in which "r" is the Are first letter (rabbit, rose) or the third letter (bare, throw)? • The correct answer is the third letter, but if you said The the first letter, you're not alone. • Most people find it easier to give a long list of Most words beginning with "r," since it's easier to search through memory by first letter. • Because those words are more available to them, Because they assume that there are more in the language although the opposite is true. • You can found the correct answer by searching You dictionary, but it may take a whole day. • We prefer using a shortcut, even if it's not always We 35 correct. Availability (cont.)
• Items can also be more available due to the Items frequency with which we encounter them. • Try this question: Which cause of death is more Try frequent, motor vehicle accidents or stomach cancer? • Most people responded that accidents were more Most frequent, but in fact stomach cancer kills more. • Since automobile accidents are reported much Since more than stomach cancer on newspapers, they are more available. • This media bias causes us to overestimate the This frequency of events.
• The representativeness shortcut says that The people tend to believe that categories are homogenous--that is, all individual members of a category are alike and are equally representative of that category. • Thus, people justify in predicting the Thus, behavior of an individual based on information about a large group, or generalizing about a large group based on information about a single individual.
37 Representativeness (cont.)
• In truth, an individual or a small group In shows little similarity to the overall group. People believe in stereotypes because of their tendency to overuse the representativeness shortcut. 38 Usefulness of Shortcut
• Make a judgment when
– Insufficient capability or time to perform complex Insufficient statistical analysis. – Very little background information Very • Shortcut can be an efficient way to process Shortcut information. • Shortcut help us get around these problems by Shortcut using what information we do have and can be accessed quickly to make predictions and judgments judgments • Shortcuts is not perfect but much better than Shortcuts random guesses. random
39 Usefulness of Shortcut
• It's difficult to be aware when we are using It's shortcuts, since we often feel confident about a decision made with almost no evidence. • Just try to be aware of using shortcuts 40 Introduction to expertise
• Experts often have an edge in problem Experts solving in a particular field. solving • Expertise in one field does not generalize Expertise to others. 41 Introduction to expertise (cont.)
• Experts seem to differ from novices in problem Experts solving in several ways. • They have more knowledge than novices, and They they organize their knowledge in a different way. • Because of that knowledge, they perceive and Because frame the problem more efficiently. • Experts also tend to break down the problem Experts into chunks and sub-goals to allow them to navigate the problem from the initial state to the goal state.
42 Expert Knowledge
• Many years of experience in solving a Many particular type of problem • They have more examples of past They problems to compare to the current one that might help them to find an appropriate solution that has been used in similar situations in the past. 43 Expert Knowledge (cont.)
• Experts draw connections between past Experts situations, finding similarities between them. • The wealth of associations gives them The easier access to their knowledge and lets them see patterns among the vast collection of individual examples. 44 Sub-goals
• Experts also tend to break problems down Experts into sub-goals through condensing a large amount of information to make the problem more manageable. • Instead of trying to get from the initial state Instead to the goal state in one leap, experts can see problem as a series of smaller problems to be solved.
• After solving similar problems for a period After of time, many experts find that some of their problem solving skills have become automatic. • An automatic skill takes up fewer An resources from attention and working memory. memory. • It allows experts to solve the problem more It quickly or to devote the saved resources to some other aspects. 46 Limits to Expertise
• One major limit on expertise is that it is not One generalizable. Being an expert in one type of problem does not increase my skills on other problems. • Experts' familiarity can harm the accuracy of Experts' their memories in other ways. Experts' memories for particular problems are less detailed than novices. 47 Limits to Expertise (cont.)
• In addition, experts' memories for problems In are vulnerable to intrusion errors. They tend to insert things into a problem that were not actually there, but that they had seen on previous similar problems. 48 Framing the problem
• The frame of a problem is the set of The assumptions about possible solutions and the attitudes being used to approach it. • These limitation can aid problem solving by These preventing us from pursuing wild and improbable paths, but limit creativity at the same time. 49 Functional Fixedness
• People tend to regard an object as if it had People only one possible function. For example, they look at a saw and see a tool only good for cutting. But, a saw could also be used as, say, a musical instrument! The failure to see other possible uses for an object is called functional fixedness. 50 Strategy Rigidity
• When trying to solve a new problem, people tend to When try a few different paths until they find one that works. However, if the same path works for each problem, people will stop trying new strategies since they have found one that appears to be reliable. This reliance on a single strategy, called strategy rigidity, can be a problem if they encounter a new problem that requires them to use a different method. A easy problem become impossible since they are stuck to one single strategy.
51 Starting Assumptions
• People also make assumptions about the People problem itself at the very start of the problemproblem solving process. They assume that some solving strategies will tend to be useful while others will not. In addition, they may make limiting assumptions about the rules of the problem and about what operators are available to them. As an example, try to solve the Nine Dot Problem Problem
52 53 To connect all dots by using: • Four straight lines Rules: Cannot lift the pen Cannot retrace your path Different direction counts a new line 54 To connect all dots by using: • Three straight lines Rules: Cannot lift the pen Cannot retrace your path Different direction counts a new line 55 Starting Assumptions (cont.)
• This problem is difficult on its own, but it is This made more difficult by the starting assumptions that people make. They assume that their lines must stay inside the square even though that limitation is not stated anywhere in the problem. 56 ...
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- Spring '11
- initial state, goal state