HCI-Lect-04.pdf

HCI Lecture 04 1  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 quest...

HCI Lecture 04 1  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. The question is processed and a valid response generated. The brain then tells the appropriate muscles (‫)العضالت‬to respond. Each of these stages takes time, which can be roughly divided into reaction time and movement time. 2  Movement Movement time is dependent largely on the physical characteristics of the subjects: their age and fitness. Reaction time varies according to the sensory channel through which the stimulus is received. A person can react to an auditory signal in approximately 150 ms, to a visual signal in 200 ms and to pain in 700 ms. 3  Movement However, a combined signal will result in the quickest response. Factors such as skill or practice can reduce reaction time, and fatigue )‫ (التعب‬can increase it. A second measure of motor skill is accuracy. This is dependent on the task and the user. In some cases, requiring increased reaction time reduces accuracy. 4  Movement Speed and accuracy of movement are important considerations in the design of interactive systems, primarily in terms of the time taken to move to a particular target on a screen. The target may be a button, a menu item or an icon, for example. The time taken to hit a target is a function of the size of the target and the distance that has to be moved. 5  HUMAN MEMORY Have you ever played the memory game? The idea is that each player has to recount a list of objects and add one more to the end. Indeed, 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. 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. 6  HUMAN MEMORY – But 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? – what happens when we forget? In order to answer questions such as these, we need to understand some of the capabilities and limitations of human memory. 7  HUMAN MEMORY Memory is the second part of our model of the human as an information-processing system. memory is associated with each level of processing. Bearing this in mind, we will consider the way in which memory is structured and the activities that take place within the system. 8  HUMAN MEMORY It is generally agreed that there are three types of memory or memory function: sensory buffers: (The sensory memories act as buffers for stimuli received through the senses.) 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 fleetingly)‫)(عابرة‬ long-term memory: (is our working memory or ‘scratch-pad’, long-term memory is our main resource. Here we store factual information, experiential knowledge, procedural rules of behavior – in fact, everything that we ‘know’) 9  HUMAN MEMORY It differs from short-term memory in a number of significant ways. First, it has a huge and 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. 10  Long-term memory processes There are three main activities related to long-term memory: storage or remembering of information, forgetting and information retrieval. First, how does information get into long-term memory and how can we improve this process? Information from short-term memory is stored in long-term memory by rehearsal(‫)بروفة‬. 11  Long-term memory processes what causes us to lose this information, to forget? There are two main theories of forgetting: decay)‫(تسوس‬ and interference. The first theory suggests that the information held in long-term memory may eventually be forgotten. The second theory is that information is lost from memory through interference. A common example of this is the fact that 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. 12  Long-term memory processes The third process is information retrieval. Here we need to distinguish between two types of information retrieval, recall and recognition. In recall the information is reproduced from memory. In recognition, the presentation of the information provides the knowledge that the information has been seen before. Recognition is the less complex cognitive)‫(ادراك‬ activity since the information is provided as a cue)‫(لمح‬. 13  THINKING: REASONING AND PROBLEM SOLVING We have considered how information finds its way into and out of the human system and how it is stored. Finally, we come to look at how it is processed and manipulated. 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? 14  THINKING: REASONING AND PROBLEM SOLVING Thinking can require different amounts of knowledge. Some thinking activities are very directed and the knowledge required is constrained. In this section we will consider two categories of thinking: reasoning and problem solving. 15  THINKING: REASONING AND PROBLEM SOLVING Reasoning: Reasoning )‫(المنطق‬is the process by which we use the knowledge we have to draw conclusions or infer)‫ (اإلستنباط‬something new about the domain of interest. There are a number of different types of reasoning: deductive)‫(استنتاجي‬, inductive)‫(استقرائية‬ and abductive. We use each of these types of reasoning in everyday life, but they differ in significant ways. 16  THINKING: REASONING AND PROBLEM SOLVING Deductive reasoning: Deductive reasoning derives the logically necessary conclusion from the given premises)‫(معطيات او دالالت‬. For example, If it is Saturday then she will go to work. Inductive reasoning: Induction is generalizing from cases we have seen to infer information about cases we have not seen. For example, if every elephant we have ever seen has a trunk, we infer that all elephants have trunks. 17  THINKING: REASONING AND PROBLEM SOLVING Abductive reasoning: The third type of reasoning is abduction. Abduction reasons from a fact to the action or state that caused it. This is the method we use to derive explanations for the events we observe. For example, suppose we know that Sam always drives too fast when he has been drinking. If we see Sam driving too fast we may infer that he has been drinking. 18  THINKING: REASONING AND PROBLEM SOLVING 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. There are a number of different views of how people solve problems. 19  THINKING: REASONING AND PROBLEM SOLVING Gestalt theory Gestalt psychologists were answering the claim, made by behaviorists, that problem solving is a matter of reproducing known responses or trial and error. 20  THINKING: REASONING AND PROBLEM SOLVING Problem space theory Newell and Simon proposed that problem solving centers on the problem space. The problem space comprises problem states, and problem solving involves generating these 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. 21  PSYCHOLOGY AND THE DESIGN OF INTERACTIVE SYSTEMS So far we have looked briefly at the way in which humans receive, process and store information and solve problems. But how can we apply what we have learned to designing interactive systems? For example, we can deduce that recognition is easier than recall and allow users to select commands from a set (such as a menu) rather than input them directly. 22 Thank You 23