HCI 1-3 Notion Note PDF

🖥️ HCI Created @July 24, 2024 5:14 PM Chapter - 1, Introduction to Human- Computer Interaction Historical Roots of HCI To achieve usability in the design of any interactive product, consider the following factors: To make a product easy to...

🖥️ HCI Created @July 24, 2024 5:14 PM Chapter - 1, Introduction to Human- Computer Interaction Historical Roots of HCI To achieve usability in the design of any interactive product, consider the following factors: To make a product easy to use, think about these things: People's Abilities: Know what most people can and can't do. Specific Users: Understand special needs of the people who will use your product. Work Environment: Consider where and how people will use your product. User Tasks: Make sure your product helps people do their jobs. Technology Limits: Be aware of what the software and hardware can and can't do. Projects often fail for several reasons: Lack of senior management commitment: Without support and involvement from top management, projects can lose direction and resources. Lack of user involvement: If users are not involved, the project may not meet their needs or expectations. HCI 1  Lack of user requirements specifications: Without clear requirements from users, the project may miss key features or functionality. Poor project planning and team problems: Inadequate planning and team issues can lead to missed deadlines, budget overruns, and other problems. Introduction to User-Centered Approach A user-centered approach focuses on users' needs throughout the software development process. Key activities include: Involving Users: Engage users in the development process to ensure their needs are understood. Obtaining Feedback: Regularly seek users' opinions and feedback on the design. Providing Prototypes: Create prototypes for users to evaluate, and use their feedback to improve and redesign the system. User-Centered Development 1. Data Collection: Gather information about users and their needs. 2. Data Analysis: Analyze the collected data to understand user requirements and preferences. 3. Prototyping: Create initial versions of the product for users to review and test. 4. Design: Develop the design based on user feedback and data analysis. 5. Evaluation: Test the product with real users to assess its usability and make improvements. Making good user interfaces is not simple. Basic misconceptions: If I (the developer) can use it, everyone can use it: Developers are often more familiar with the product, so what seems easy to them might be hard for HCI 2  others. If our non-technical staff can use it, everyone can: Non-technical staff might have more knowledge about the product than typical users, so their experience may not reflect that of a regular user. Good user interfaces are just common sense: Designing good interfaces requires careful planning and understanding of user needs, which goes beyond just common sense. A system is usable if all style guidelines are met: Following style guidelines is important, but it doesn’t guarantee usability. Real usability comes from testing and understanding how users interact with the system. Computer Graphics 1. Early Beginnings: Computer graphics started with early technologies like CRT (Cathode Ray Tube) screens and pen devices used in the early days of computers. 2. Development of Techniques: These early technologies led to the creation of new ways for people to interact with computers, such as drawing and manipulating images on screens. 3. Advancements: Over time, work in computer graphics has improved algorithms (step-by-step procedures) and hardware (physical devices) to create and display more realistic images, like detailed machine parts or medical scans. 4. Interactive Graphics: Computer graphics also focuses on how users can interact with and manipulate these realistic images. For example, in CAD/CAM systems, users can design and adjust models of parts or machinery. In summary, computer graphics has played a key role in developing methods and tools for more interactive and realistic computer interfaces. Operating Systems HCI 3  Here's a simple explanation: 1. Operating Systems and Input/Output Devices: Operating systems (OS) created ways for computers to communicate with devices like keyboards, mice, and printers. 2. Examples of OS Contributions to HCI: Tuning System Response Time: Adjusting the computer's speed to match how quickly people can interact with it. Multiprocessing: Allowing multiple tasks to run at the same time, which helps keep the system responsive. Windowing Environments and Animation: Supporting multiple windows and smooth animations on the screen, making it easier for users to manage different tasks. 3. Advanced Tools: These developments led to the creation of "user interface management systems" and "user interface toolkits," which are tools and frameworks to help developers build user-friendly interfaces more easily. In summary, operating systems have played a crucial role in making computers more responsive, efficient, and user-friendly, contributing significantly to the field of HCI. Origins and Evolution of Human Factors, Ergonomics, Industrial Engineering, and Cognitive Psychology Simpler Explanation People have been studying how humans use things for a long time. Making things easy to use: During World War II, people started thinking about how to design things that were easy for people to use. This led to the study of human factors. How people work: Another group of people studied how people worked. They wanted to make work easier and safer. This is called ergonomics. HCI 4  Faster work: Other people tried to find ways to make work go faster. They looked at how people moved and used tools. This is called industrial engineering. How people think: Scientists also studied how people think and learn. This is called cognitive psychology. Computers changed everything. When computers came along, all these groups of people started working together. They wanted to make computers easy to use and helpful for people. They learned from each other and found new ways to design things. Today, we use what they learned to make technology better for everyone. Human Factors VS Ergonomics In HCI, human factors make sure systems are easy to understand and use, while ergonomics make sure they are physically comfortable and safe to use. The Future of Computers: A Simple Explanation Computers are changing fast! Here's what we can expect: Computers Everywhere Computers will be in lots of places, not just on desks. You'll be able to use them anywhere with different kinds of wireless connections. Super Smart Computers Computers will do lots of things. HCI 5  There will be so many things to do that it will be hard to learn how to use them all. Better Pictures and Videos Computers will show really good pictures and videos. These will be easy to make and watch. Computers That Talk and Listen Computers will understand what you say and talk to you. They will show pictures, videos, and text. Faster Computers Computers will be much faster. You will be able to do things on them very quickly. Big and Small Screens Computers will have big screens for lots of people to see. They will also have small, light screens that you can carry with you. Computers in Everything Computers will be inside lots of things around you, like cards or toys. These things will talk to each other and to you. Computers for Groups Computers will help groups of people work together. This will change how we work and do things. More Information There will be lots of information available on computers. It will be easy to find what you need. HCI 6  Computers are getting better all the time, and they will be a big part of our lives in the future. Chapter - 2 Interaction To design something for people, we need to know how they see, think, and move. The Model Human Processor, made by Card, Moran, and Newell in 1983, helps us understand this. It breaks it down into three parts: 1. **Perceptual System**: How we see and hear things. 2. **Motor System**: How they change(manpulate) objects. 3. **Cognitive System**: How we think and solve problems. Each part works with its own memory and has rules for how they work together. Factors to be considered for interaction  Information input/output  Information stored in memory  sensory, short-term, long-term  Information processed and applied  Emotion influences human capabilities  Each person is different. Visual Inputs Receiving Perception of Stimulus HCI 7  Receiving Light: The eye collects light from objects, which bounces off and enters the eye. Focusing Light: The eye focuses light onto the retina, creating an upside- down image. Retina Functions: Rods: Detect light in low-light conditions. Cones: Detect colors and details in bright light. Transforming Light: Rods and cones convert light into electrical signals. Sending Signals: Electrical signals travel to the brain via the optic nerve. Detecting Patterns and Movement: Ganglion cells in the brain analyze signals to recognize patterns and movement. Processing and Interpretation of Stimulus Size and Depth: Visual Angle: The perceived size of an object based on its portion of your view. Size Constancy: Understanding that an object's size remains constant despite distance. Depth Perception: Depth perception is how we tell how far away something is. Brightness: Subjective Reaction: Perception of brightness influenced by light intensity and eye response. Luminance: is how much light something sends out. Just Noticeable Difference: The smallest detectable change in brightness. Color: Hue: The color's name (e.g., red, blue). Intensity: The color's brightness or strength. HCI 8  Saturation: The color's purity or intensity. Color Blindness: Difficulty distinguishing colors, affecting about 8% of men and 1% of women. Constructivism Theory: Our brains create simplified mental models of what we see, focusing on important details. Design Implication: Prioritize key information in designs, as people often ignore minor details. Context in Vision: Context aids in understanding visual information (e.g., recognizing letters within a word). Design Implication: Focus on key information and use context to clarify designs. Reading Process Stages: Visual Pattern: Recognizing the shape of words. Decoding: Translating shapes into language. Understanding: Comprehending words within sentences using grammar and meaning. During the first two stages, the eye makes saccades (jerky movements), followed by fixations. The eye moves both forwards and backward over the text called, regression. Auditory Input (Hearing) Sound Reception: The ear captures air vibrations and sends them to the brain. Filtering: The ear helps to ignore background noise and focus on important sounds. Uses of Non-Speech Sounds: HCI 9  Attention: Alerting users to events or errors. Status Information: Indicating task progress. Confirmation: Confirming actions. Navigation: Guiding users through systems. Characteristics of Sound: Pitch: How high or low a sound is. Loudness: The volume of a sound. Timbre: The quality or type of sound. Touch (Haptic Perception) Touch: Sensation through the skin, crucial for visually impaired individuals. Types of Receptors: Thermoreceptors: Detect temperature. Nociceptors: Detect pain. Mechanoreceptors: Detect pressure. Sensitivity: Different areas of the skin have varying sensitivity levels. Movement and Reaction Time Reaction Time: reaction time + movement time. Movement Time: The time taken to move after reacting. Types of Stimuli: Visual: Approximately 200 milliseconds. Auditory: Approximately 150 milliseconds. Pain: Approximately 700 milliseconds. Factors: Reaction time affects accuracy, especially for inexperienced users. HCI 10  If it takes longer for someone to respond to something, they are less likely to do it correctly if they are new at it. But if someone is really good at something, taking longer to respond won't affect how well they do it. 2.3 Human Memory Memory is essential for daily life, storing knowledge, skills, and experiences. It's divided into three types: Sensory Memory Sensory memory is like a brief holding area for information that comes in through our senses. It's very short-lived and easily replaced by new information. There are different types of sensory memory for each sense: Iconic memory: for what we see Echoic memory: for what we hear Haptic memory: for what we touch To move information from sensory memory to our working memory (short-term memory), we use attention. This means focusing on specific information and ignoring the rest. Short-Term Memory (STM) Short-term memory is like a temporary workspace in your brain. It holds a small amount of information for a very short time. Think of it as the place where you keep the information you're currently using, like remembering a phone number while you dial it. HCI 11  Here are some key points about short-term memory: Limited capacity: You can only hold a small amount of information at once, usually around 5-9 items. Short duration: Information fades quickly, usually within a few seconds, unless you actively rehearse it. (Rapid access ~ 70ms, Rapid decay ~ 200ms) Vulnerable to interference: New information can easily replace old information in short-term memory. Long-Term Memory (LTM) Long-term memory is where we store information for extended periods. Unlike short-term memory, it has a vast capacity and can hold information for a long time. This is where we store facts, skills, and personal experiences. While it takes longer to access information from long-term memory compared to short-term memory (about 1/10 of a second), the information is less likely to be forgotten. There are two main types of long-term memory: Episodic memory: Stores personal experiences and events. Semantic memory: Stores facts, concepts, and general knowledge. Semantic memory is organized in a network-like structure, where related concepts are connected. This allows us to infer new information based on what we already know. We'll explore these memory models in more detail later. LTM can be modelled (Represent) using: There are several ways to represent how information is stored in long-term memory. Here are some common models: 1. Semantic Networks Concept-based: Knowledge is represented as a network of interconnected nodes (concepts). HCI 12  Relationships: Links between nodes show how concepts are related. Inheritance: Information can be inherited from higher-level nodes to lower- level nodes. Example: In an "animal" network, "bird" inherits the property of "can fly" from the higher-level node "bird." 2. Frames Structure-based: Information is organized into structures called frames, which have slots for specific details. Slots: These slots represent attributes or values associated with a concept. Example: A "car" frame might have slots for "color," "make," "model," and "year." 3. Scripts Event-based: Knowledge about familiar events or routines is stored as scripts. Slots: Scripts have slots for roles, props, and actions involved in the event. Example: A "restaurant" script might include roles like "customer," "waiter," and actions like "ordering," "eating," and "paying." 4. Production Rules Rule-based: Knowledge is represented as "if-then" rules. Conditions and actions: If a specific condition is met, a particular action is taken. Example: "If it is raining, then take an umbrella." These models provide different ways to understand how our brains might organize and store complex information. These models help explain how we store and use information in our long-term memory. LTM Model: Semantic Network Model HCI 13  Semantic memory is how our brains organize facts, concepts, and their relationships. It's like a vast network of connected ideas. Access to information: You can quickly retrieve facts and knowledge. Relationships between information: Ideas are linked together, helping you understand how things connect. Inference: You can make educated guesses or deductions based on what you know. The semantic network is a model that explains how our long-term memory is organized. Imagine it as a vast web of interconnected ideas or concepts. Key features of a semantic network: Nodes: These represent concepts or pieces of information. Links: These connect nodes and show relationships between them. Inheritance: Information can be inherited from higher-level nodes to lower- level nodes. For example, if "bird" can fly, then a "sparrow" (a type of bird) can also fly. Associations: Connections between nodes are strengthened through repeated use or association. How it works: When you think of a concept, it activates the corresponding node in the network. This activation can spread to related nodes, helping you retrieve information quickly. For example, thinking about "dog" might also activate related concepts like "bark," "loyal," or "pet." Would you like to explore another model of long-term memory, or delve deeper into how semantic networks work? HCI 14  There are 3 main activities related to LTM: 1. Storage: Information moves from short-term memory (STM) to LTM through rehearsal. Effective storage involves distributed practice over time and meaningful information that can be linked to existing knowledge. 2. Forgetting: Two primary theories explain forgetting: Decay: Information gradually fades away over time. Interference: New or old information interferes with the retrieval of other information (retroactive and proactive inhibition). Emotional factors also influence forgetting. 3. Retrieval: Information is recalled from LTM through cues like categories and imagery. Recognition is often easier than recall. Key Factors in LTM Rehearsal: Repeated practice strengthens memory. HCI 15  Distribution of practice: Spreading learning over time improves retention. Meaningfulness: Information is better remembered when it is connected to existing knowledge. Interference: New and old information can compete for retrieval. Emotional factors: Emotions can influence memory formation and retrieval. Retrieval cues: Clues can aid in recalling information. Note: Recall is like trying to remember a friend's phone number without looking it up. You have to think hard and pull the information out of your brain. It's tough! Recognition is easier. It's like seeing your friend's number on a list of names and numbers. You can quickly point it out because you've seen it before. So, recall is remembering something without any help, while recognition is knowing something when you see it. Thinking Thinking needs different amounts of knowledge. Some thinking is easy because we already know a lot about it. Other times, we need to know lots of things from different subjects. How We Think Reasoning: Figuring things out. 1. Deductive Reasoning(General to specific): Using rules to reach a conclusion. Example: All birds fly. This is a bird. So, it flies. Math: All angles in a triangle add up to 180 degrees. This shape is a triangle. Therefore, its angles add up to 180 degrees. Logic: If it's raining, the ground is wet. It's raining. Therefore, the ground is wet. 2. Inductive Reasoning(Specific to general): Learning from examples. Example: Seeing many white swans makes you think all swans are white. HCI 16  Science: Every crow you've ever seen is black. Therefore, all crows are black. (This is an example of a generalization based on limited observations.) Weather: It's been cloudy for the past week. It's probably going to be cloudy tomorrow. 3. Abductive Reasoning: Guessing the reason for something. Example: Seeing wet grass makes you think it rained. Mystery: You find footprints in the sand. You conclude that someone walked there. Crime Scene: A broken window and missing valuables suggest a burglary. Problem-solving Problem-solving is figuring out how to do something new. We use the things we already know to find a solution. Different Ways to Solve Problems: 1. Gestalt Psychology This approach believes that solving problems often involves a sudden "aha!" moment. You look at the problem in a new way, and the solution becomes clear. It's like seeing a hidden shape in a picture. Example: Figuring out a riddle or a complex math problem suddenly after staring at it for a while. 2. Analogy (Using Similarities) We often solve problems by comparing them to similar problems we've solved before. For example, if you've built a sandcastle, you can use those skills to build a Lego tower. However, if the problems are very different, it's harder to find similarities. HCI 17  Example: Using your knowledge of cooking to figure out how to bake a new cake. 3. Skill Acquisition (Learning and Getting Better) When we practice something, we get better at it. Our brains learn to group information together (chunking) to make it easier to remember and use. This helps us solve problems quickly. Example: Learning to ride a bike or play a musical instrument. 4. Analyzing means-ends (Breaking Down the Problem) This method involves looking at all the possible steps or options to solve a problem. It's like planning out different paths to reach a goal. This works well for puzzles or games with clear rules. Example: Solving a Rubik's cube by considering all possible moves and their outcomes. In short, these are different ways our brains try to solve problems. Sometimes we use one method, sometimes another, and often we use a combination of them. Skill acquisition Learning new skills is about getting better at something. Experts are really good at what they do because their brains organize information in a special way that helps them think and act quickly. Stages of Skill Learning There are three main steps to learning a new skill: 1. Beginner Stage: You're just starting out. You follow basic rules, but it takes a lot of thought and effort. Example: A new driver following traffic rules carefully. 2. Intermediate Stage: HCI 18  You start to get better. You develop specific methods for the task. Example: A driver learning how to parallel park. 3. Expert Stage: You're really good at it. You can do things quickly and automatically. Example: An experienced race car driver. In short, learning a new skill takes time and practice. As you practice, your brain gets better at processing information, and you become faster and more accurate. Errors and mental models We all make mistakes. There are two main types: 1. Slips Doing the wrong thing by accident. Examples: Typing the wrong letter, spilling your coffee, missing an exit. Caused by tiredness, distraction, or changes in routine. 2. Mistakes Doing the wrong thing because you think it's right. Examples: Using the wrong formula in math, misunderstanding instructions. Caused by incorrect knowledge or understanding. Mental models are how we picture things in our heads. They help us understand how things work. But if our mental model is wrong, we might make mistakes. For example, if you think a car works like a bicycle, you might be surprised when you try to steer it by turning the handlebars. Emotions HCI 19  Emotions are our body's reactions to things that happen around us. They involve both physical and mental responses. Theories of Emotion There are different ideas about how emotions work: James-Lange Theory: We feel emotions because of physical changes in our body. For example, we feel scared because our heart races. Cannon-Bard Theory: Emotions and physical changes happen at the same time. Schachter-Singer Theory: Our emotions depend on how we interpret our physical reactions based on the situation we're in. Emotions and Behavior Affect is the general feeling state that comes from physical reactions. Positive emotions help us think creatively and solve problems. Negative emotions can make it harder to concentrate and solve problems. Stress is a negative emotion that can make problem-solving even more difficult. Pleasant designs can create positive emotions and make it easier to use products. In short, our emotions influence how we think and act. Understanding emotions is important for creating user-friendly products and services. Individual Differences People are not all the same. While general principles can be applied to many people, it's crucial to consider individual differences when designing products or systems. Importance of Considering Individual Differences Inclusive Design: Creating designs that work for as many people as possible. HCI 20  User Satisfaction: Meeting the specific needs of different user groups. Effective Products: Designing products that are tailored to specific user requirements. Factors Affecting Individual Differences Long-term differences: These are stable characteristics like gender, physical abilities, and intelligence. Short-term differences: These are temporary states like stress, fatigue, or mood. Changing differences: These factors evolve over time, such as age. Identifying User Groups To address individual differences effectively, designers should: Divide users into specific groups based on shared characteristics. Analyze the potential impact of design decisions on each group. Ensure that designs don't exclude any significant portion of the user population. By understanding and accommodating individual differences, designers can create products and systems that are more usable, efficient, and satisfying for a wider range of people. Knowing about psychology can help. Psychology is the study of the mind and behavior. Understanding how people think and feel can help us create better designs. For example, we know that it's hard to see blue things, so we shouldn't use blue for important information. But it's not always simple. We need to understand the whole picture, not just one small part. Would you like to learn about a specific example of how design can be improved by understanding people better? HCI 21  Chapter - 3 Interaction Key Components of a Computer System A computer system is composed of interconnected components that work together to process information. The primary elements influencing user interaction are: Input Devices Text entry: Keyboards are commonly used for entering textual data. Pointing: Devices like mice, touchpads, and styluses allow for interaction with visual interfaces. Output Devices Visual displays: Screens, both small (e.g., smartphones) and large (e.g., monitors), present information visually. Digital paper: Emerging technology offering a paper-like display for reading and writing. Virtual reality: Specialized devices create immersive experiences through interactive displays. Physical interaction: Haptic feedback devices provide tactile sensations. Paper Output: Traditional method of producing printed documents. Input: Can be scanned to convert physical documents into digital format. Memory Stores data and instructions for the computer's operation. Processing The central processing unit (CPU) executes commands and performs calculations. HCI 22  These components collectively enable a computer system to receive input, process information, and produce output in various forms, catering to different user needs and applications. Interactivity: Talking Back and Forth with Computers Interactivity (with or without a computer) is a process of information transfer. How Computers Used to Talk (batch processing) A long time ago, computers were like slow talkers. You had to give them a big pile of information all at once, and then wait a long time for an answer. It was like writing a long letter and waiting for a reply. How Computers Talk Now Today, computers are like fast texters. You can ask them something, and they almost instantly give you an answer. This is called interactive. It's like having a quick chat with a friend. So, interactivity means that computers can talk to you quickly and easily. Keyboards The most common text input device Allows rapid entry of text by experienced users Key press causes a character code to be sent Usually connected by cable, but can be wireless Layout – QWERTY Common Layout: Used almost everywhere, but: Other Keys: Non-letter keys are placed differently in some places. Accented Symbols: Needed for different languages. Small Differences: Between UK and USA keyboards. HCI 23  Typing Speed: QWERTY isn’t the fastest for typing. Other Layouts: Can be faster, but most people stick with QWERTY because they’re used to it. Alternative Keyboard Layouts Alphabetic Layout: Keys are in alphabetical order. Speed: Not faster for trained typists or beginners. Dvorak Layout: Key Placement: Vowels and some consonants on the left hand; only consonants on the right. Efficiency: Common letters are under the strongest fingers; letter combinations alternate between hands. Benefits: 10-15% improvement in typing speed and less fatigue. Challenge: Most people stick with QWERTY, making it hard to switch. Special Keyboards: Purpose: Designed to reduce fatigue (extreme tiredness) and prevent repetitive strain injury (RSI) (overuse injury). Example: The Marlon left-handed keyboard for one-handed use. For example: 1. Chord Keyboards Few Keys: Usually only four or five. Typing Method: Letters are typed by pressing combinations of keys. Compact: Small size, great for portable devices. Learning: Short learning time because key presses resemble letter shapes. Speed: Can be very fast once trained. HCI 24  Challenges: Social resistance to using them and potential fatigue (extreme tiredness) from extended use. 2. Phone Pad and T9 Entry Numeric Keys: Typing involves multiple presses on the number keys (e.g., 2 for a, b, c). T9 Predictive Text: Method: Type as if each letter has a single key. Function: Uses a dictionary to predict and guess the correct word. Numeric Keypads Purpose: Used for quickly entering numbers. Examples include calculators, PC keyboards, telephones, and ATMs. Variety: Not all numeric keypads have the same key arrangement. Handwriting Recognition Input Method: Text is entered into a computer using a pen and digitizing tablet, allowing for natural interaction. Technical Challenges: Capturing all necessary information like stroke path and pressure naturally. Breaking down connected handwriting into individual letters. Accurately interpreting each letter. Dealing with different handwriting styles. Usage: Commonly found in personal digital assistants (PDAs) and tablet computers. Speech Recognition HCI 25  Rapid Improvement: Technology is getting better. Best Use Cases: For a single user with initial training to learn their voice and habits. In systems with a limited vocabulary. Useful when hands or eyes are occupied or for users with disabilities. Challenges: Interference from external noise. Issues with pronunciation. Handling large vocabularies. Limited feedback to the user. Speech is a single-channel mode, meaning only one person can speak at a time. Usage Scenarios: As an alternative to keyboard text entry in current software. With new software specifically designed for speech recognition. In situations where keyboards are impractical or impossible to use. Design Guidelines: Consider using voice recognition when hands or eyes are occupied. Avoid using it in noisy or insecure environments. Use familiar vocabulary to help users pronounce words more consistently. Positioning, Pointing, and Drawing 1. The Mouse Description: A handheld pointing device that is very common and easy to use. Challenges: Beginners may face hand-eye coordination problems. HCI 26  Characteristics: Planar Movement: Moves in a 2D plane. Buttons: Typically has 1 to 3 buttons for selection, options, or drawing. How It Works Motion Detection Methods: Mechanical: Uses a ball on the underside that rolls as the mouse moves. Works on most flat surfaces. Optical: Uses a light-emitting diode (LED) to detect motion. Can work on special pads or desks. Less affected by dust and dirt. Measures changes in reflected light to calculate movement in the X and Z planes. 2. Touchpad Description: A small, touch-sensitive surface. Function: Moves the mouse pointer by stroking or dragging fingers across it. Usage: Mainly found in laptop computers. Trackball Description: An inverted mouse where the ball rotates inside a stationary housing. Advantages: Allows for very fast movement, useful for gaming. Usage: Used in some portable and notebook computers. 3. Joystick Description: A control with buttons for selection. Usage: Commonly used for computer games, aircraft controls, and 3D navigation. Keyboard Nipple/Trackpads Description: A small joystick is located in the middle of the keyboard. Usage: Found in some laptop computers; controls the rate of movement across the screen. HCI 27  4. Touch-sensitive Screen Function: Detects the presence of a finger or stylus on the screen, acting as a direct pointing device. Advantages: Fast and requires no special pointer. Good for menu selection. Suitable for hostile environments; resistant to damage. Disadvantages: Can leave marks on the screen. Less accurate due to the blunt nature of fingers. Hard to select small areas or perform precise drawings. Using it for extended periods can be tiring. Stylus Description: A small pen-like tool used to draw directly on the screen. Technology: Can use touch-sensitive surfaces or magnetic detection. Usage: Common in PDAs, tablet PCs, and drawing tablets. Light Pen Description: An older technology that uses light from the screen to detect location. Current Usage: Rarely used today. Eye Gaze Function: Controls the interface based on the direction of eye gaze (e.g., look at a menu item to select it). Technology: Uses a laser beam reflected off the retina. Advantages: Potential for hands-free control. Accuracy: High accuracy requires a headset. HCI 28  5. Cursor Keys Used for two-dimensional navigation. Four keys (up, down, left, right). Most common layout is the inverted “T” shape. 6. Discrete Positioning Controls Found in phones, TV controls, etc. Includes cursor pads or mini-joysticks. Used for discrete left-right, up-down movements. Mainly for menu selection. Example: The directional pad (D-pad) on game controllers or TV remote controls. Guidelines for Pointing Device Selection Use Touchscreen When: Training is minimal. Frequency of use is low. Desk space is small. Task requires little or no text input. Mouse vs. Trackball: Mouse is generally faster. General Tip: Minimize hand and eye movement between input devices. Display devices Bitmap Displays Description: Screens made up of a vast number of colored dots (pixels). HCI 29  Resolution: Number of pixels on the screen (width x height). Examples: SVGA 1024 x 768, PDA 240 x 400. Example: A standard computer monitor might have a resolution of 1920 x 1080. Density: Pixels per inch (dpi). Typically between 72 and 96 dpi. Example: A high-resolution smartphone screen might have 300 dpi. Aspect Ratio: Ratio between width and height. Common ratios: 4:3 for most screens, 16:9 for wide-screen TVs. Example: Many modern TVs and monitors use a 16:9 aspect ratio for a widescreen display. Cathode Ray Tube (CRT) How it works: Shooting tiny particles: The TV shoots out tiny, invisible particles called electrons from the back of the screen. Controlling the particles: These particles are guided and shaped by magnets. Making light: When the particles hit the front of the TV, they make the screen glow. This is where the picture appears. Usage: Used in TVs and computer monitors. Health Hazards of CRTs HCI 30  X-rays: Mostly absorbed by the screen, but some can escape from the back. Phosphor Radiation: Very low levels, not a big concern. Radio Frequency and Ultrasound: Emitted by the screen. Electrostatic Fields: Can cause rashes; depends on distance and humidity. Electromagnetic Fields: Can create small currents in materials, including the human body. Effects: Eyes: Increased risk of cataracts. Reproductive Health: Concerns about miscarriages and birth defects. Health Tips Don’t sit too close to the screen. Avoid very small text. Take breaks from looking at the screen. Don’t place the screen in front of a bright window. Work in a well-lit area. Liquid Crystal Displays (LCD) Advantages: Smaller and lighter. No radiation problems. Common Uses (found in): PDAs, portable devices, notebooks, desktops, and home TVs. Dedicated displays like digital watches and mobile phones. Features: Reflects light rather than sending it out, which reduces eye discomfort. HCI 31  When it says "reflects light rather than sending it out, which reduces eye discomfort," it means that the display doesn't produce its own light, but instead, it uses external light (like sunlight or room light) to make the screen visible. This is different from screens that emit their own light, which can sometimes cause eye strain, especially after long periods of use. In simpler terms, LCD screens are easier on your eyes because they reflect existing light rather than shining a bright light directly at you. This reflective quality is part of why devices like digital watches and some mobile phones with LCD screens can be more comfortable to look at for longer times. More flexible and offers additional functions compared to older display types. Large Displays Uses: Ideal for meetings, lectures, and other group settings. Technologies: Plasma: Usually used for wide screens. LCD (Liquid Crystal Display): These screens use a backlight behind liquid crystals to create images. The liquid crystals control how much light gets through, forming the picture you see. LCDs are usually thinner, use less power, and work well in bright rooms because of their backlight. HCI 32  Plasma: Plasma screens use tiny cells filled with gas. When the gas is charged with electricity, it glows and forms the image. Plasma screens are known for showing deep colors and clear images, especially in dark rooms. However, they are thicker, use more power, and are not as bright as LCDs in well-lit environments. In short, LCDs are more common today because they are thinner, lighter, and better in bright rooms, while Plasma screens were once popular for their rich colors and better performance in darker settings. Video Walls: Made up of many small screens combined. Projected: Uses RGB lights or LCD projectors. Back-projected: Uses glass with a projector behind it. Situated Displays Location: Found in public or semi-public places. Can be large or small, for large crowds or small groups. Types: Information Displays: Show information relevant to the location. Interactive Displays: Use a stylus or touch-sensitive screen for user interaction. Key Point: The meaning or function of the display is linked to its location. Digital Paper and 3D Digital Paper: Also called interactive paper. HCI 33  Patterned paper used with a digital pen to create handwritten digital documents. The paper’s dot pattern tracks the pen’s position and transfers the handwriting to a computer. Example: Livescribe Smartpen with its special dot-patterned notebooks. Virtual Reality (VR) and 3D Interaction: VR: Allows users to move and interact in a computer-simulated environment, creating a 3D experience similar to real life. Example: Oculus Rift or HTC Vive VR headsets. 3D Displays: Desktop VR: Uses a regular screen with mouse or keyboard control. Creates a 3D effect through perspective and motion. Example: 3D games on a computer with standard monitors using software like NVIDIA 3D Vision. Seeing in 3D: Stereoscopic Vision: Uses multiple display devices to create depth. Example: 3D movies viewed with 3D glasses in a cinema. VR Helmets: Track head and possibly eye movements. Example: Oculus Quest 2 VR headset. Screen with Shuttered Glasses: Glasses that alternate blocking each eye to produce a 3D effect. Example: NVIDIA 3D Vision glasses used with compatible monitors. Sounds Types of Sounds: Beeps, bongs, clonks, whistles. Used for error indications or confirming actions (e.g., key clicks). HCI 34  Speech Output: Digitized Speech: Recorded human speech stored in digital format. Synthesized Speech: Generated by computers using speech processing techniques. Advantages: Useful when the user's eyes are busy or they cannot access the screen. Disadvantages: Limited Information: Speech provides less detail because it’s fleeting. Privacy and Security: Less secure in open environments. Single Channel Mode: Can’t listen to multiple messages at once. Speech Speed: Spoken words (~120-180 words per minute) are slower than reading (~200-300 words per minute). Guidelines for Speech Output: Use When: Eyes are busy or screen access is limited. Avoid When: Privacy and security are crucial, multiple messages are needed at once, or high frequency of use. Output Rate: Approximately 180 words per minute. Voice Prompts: Present the goal first and the action last. Example: “For playing the message, press two.” “Please press two to play the message.” Touch and Feel Importance: Games: Vibration feedback enhances the gaming experience. Simulations: Provides the realistic feel of tools, like surgical instruments. HCI 35  Haptic Devices: These devices create touch sensations, allowing users to "feel" virtual objects. Texture, Smell, Taste Limitations: Current technology has very limited ability to replicate these senses. Physical Controls Specialist Controls: Required for specific applications such as industrial machinery or consumer products. Example: Emergency Stop Button: A large red button on factory machines, used for quickly stopping operations in an emergency. Clear Dials: Used on equipment like ovens or industrial machines, where precise control over settings (like temperature or speed) is needed. Clear markings on dials ensure accurate adjustments. Paper: printing and scanning 1. Paper as Input and Output: Paper is traditionally seen as an output medium, but it can also serve as an input medium through processes like OCR (Optical Character Recognition) and scanning. 2. Printing: Images printed on paper are made up of small dots, allowing for any character set or graphic to be printed. Critical Features of printing include: Resolution: The size and spacing of dots, measured in dots per inch (dpi). Speed: Usually measured in pages per minute (ppm). HCI 36  3. Types of Dot-based Printers: Dot-Matrix Printers: Use an inked ribbon(like a typewriter) and a line of pins that strike the ribbon to create dots on the paper. Typical resolution ranges from 80-120 dpi. Ink-jet and Bubble-jet Printers: Tiny blobs of ink are sent from the print head to the paper. Typically offer 300 dpi or better. Laser Printers: Work similarly to a photocopier by depositing electrostatic charges on a drum, which picks up toner and rolls it onto the paper before fixing it with heat. Typically offer 600 dpi or better. Printers Explained - Laser, Inkjet, Thermal, & Dot Matrix (youtube.com) 4. Fonts: the particular style of text. Different fonts affect the style of printed text (e.g., Courier, Helvetica, Palatino). Readability of Text: Lowercase letters are easier to read in word form. Uppercase letters are better for individual letters and non-words, such as flight numbers (e.g., BA793 vs. ba793). 1. Scanners: Types of Scanner (youtube.com) Scanners convert paper documents into digital bitmaps. Types of Scanners: Flat-bed Scanners: Paper is placed on a glass plate, and the whole page is scanned into a bitmap. HCI 37  Hand-held Scanners: The scanner is manually passed over the paper, typically digitizing a strip 3-4 inches wide. Typical resolutions range from 600–2400 dpi. Scanners are used in desktop publishing, document storage, and retrieval systems to reduce paper use. Optical Character Recognition (OCR) Function: OCR converts scanned bitmap images into editable text. Handling Different Fonts: Advanced OCR systems can segment text, break it down into lines and arcs, and decipher characters from various fonts. Page Format Consideration: OCR must account for columns, pictures, headers, and footers to accurately interpret the text layout. Memory Short-Term and Long-Term Short-Term Memory - RAM: Random Access Memory (RAM): Found on silicon chips. Fast access time (~100 nanoseconds). Typically volatile, meaning it loses information when power is turned off. Some non-volatile RAM is used to store basic setup information. Long-Term Memory - Disks: Magnetic Disks: Floppy Disks: Store around 1.4 MB. Hard Disks: Typically range from 40 GB to several hundred GB. Access time is about 10 milliseconds. HCI 38  Optical Disks: Use lasers to read and write data. More durable than magnetic disks. Examples include CD-ROMs and DVDs. Flash Memory: Silicon-based but retains data even without power. Common in USB drives, PDAs, cameras, etc., for data storage and transfer. Compression and Storage Formats Compression: Purpose: Reduces the amount of storage needed. Lossless Compression: Allows exact recovery of text or images (e.g., GIF, ZIP). Works by identifying and shortening repeated patterns (e.g., AAAAAAAAAABBBBBCCCCCCCC becomes 10A5B8C). Storage Formats - Text: ASCII: 7-bit binary code representing each letter and character. UTF-8: 8-bit encoding, supports a wide range of characters (Unicode). RTF (Rich Text Format): Stores text with formatting and layout details. SGML (Standardized Generalized Markup Language): Treats documents as structured objects. XML (Extended Markup Language): A simpler version of SGML, commonly used in web applications. Storage Formats - Media: Images: Various formats (e.g., PostScript, GIF, JPEG, TIFF, PICT) with different compression methods. HCI 39  Audio/Video: Numerous formats (e.g., QuickTime, MPEG, WAV) often require compression, especially for streaming and network delivery, using indexing for easy access. Processing and Networks Processing Speed: Design Assumptions: Designers often assume processors are fast and create more complex interfaces. Problems with Slow Processing: Cursor Overshooting: When the system lags, it may buffer key presses, causing the cursor to jump unexpectedly. Icon Wars: Users may click multiple icons due to delayed response, leading to sudden and chaotic system reactions. Problems with Fast Processing: Overly Fast Responses: For example, help screens might scroll too quickly, making the text difficult to read. Limitations on Interactive Performance: 1. Computation Issues (processing bound): If calculations take too long, users get frustrated. "Computation bound" means the system is slow because it takes a long time to do calculations. If the calculations are too complex or take too much time, it can make everything else slow and unresponsive. Example: If you’re running a complex math program, and it’s slow because it’s doing a lot of calculations, that’s being computation-bound. 2. Storage Channel Issues: Slow transfer of data from disk to memory causes delays. HCI 40  This means the system is slow because data takes too long to move from the hard drive to the computer's memory. Example: If opening a large file from your hard drive takes a long time to load into memory, that's a storage channel-bound issue. The delay in transferring the data makes everything feel slower. 3. Graphics Issues: Updating graphics can be slow. Adding a special graphics processor can help. Graphics Bound: This means the system is slow because updating or rendering graphics takes too much time. Example: If a video game is lagging or moving slowly because it takes a long time to render the images on screen, that's a graphics-bound issue. 4. Network Capacity: Slow network speeds can make things lag when many computers share resources like files and printers. This means the system is slow because the network connection is too slow or overloaded. Example: If it takes a long time to download a file or stream a video because the network is too slow, that's a network capacity issue. Networked Computing: Networks allow access to: Large memory and processing power Other people (group projects, email) Shared resources, especially the web HCI 41  Issues: Network Delays: Slow response times due to slow connections. Conflicts: Problems when multiple people update the same data. Unpredictability: Future network issues or changes that can affect performance. Example 1: Basic Computer Architecture Definition: The basic architecture of a computer system, from a user interaction perspective, includes the computer itself, input devices (like a keyboard and mouse), output devices (like a screen), and hard copy devices (like printers). Example: Computer System: A desktop setup might have a monitor for displaying information, a keyboard for typing, and a mouse for navigating. Input Devices: You use the keyboard to type text and the mouse to point and click on items. Memory: The computer has two types of memory: short-term memory (RAM) that is lost when the computer is turned off, and long-term memory (like a hard drive or SSD) that stores data even when the computer is off. HCI 42