Answer to Question Q1a
Human-computer interaction (HCI) according to SIG CHI (the Special Interest Group on Computer-Human Interaction of the Association for Computing Machinery) is defined as a discipline concerned with the design, evaluation, and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them.





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Answer to Question Q1b
Usability refers to how user-friendly and efficient a product or system is for its intended users. It focuses on the ease with which the users can learn to use the product, the efficiency of the product in performing its tasks, and the level of satisfaction the users feel while interacting with it. Key elements of usability include effectiveness, efficiency, and satisfaction.

User experience (UX), on the other hand, encompasses all aspects of the end-user's interaction with the company, its services, and its products. It is a broader concept than usability, accounting for the emotions, perceptions, and responses of the user before, during, and after using a product or system. UX covers the holistic experience, including usability, but also takes into consideration design, branding, function, and even the emotional impact on the user.

In summary:
- Usability is about the ease of use and functionality of a product.
- User experience is about the overall feel and impact of the product on the user.





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Answer to Question Q1c
PACT stands for People, Activities, Context, and Technologies.





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Answer to Question Q1d
P (People): A busy working mom uses the app to keep track of groceries needed for the week.
A (Activities): She checks and updates the shopping list throughout the week as she notices items running out.
C (Context): The app is used at home and on the go, possibly in noisy environments like her kids' sports practice.
T (Technology): The app is accessed via her smartphone which she carries with her at all times.





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Answer to Question Q2a
1. The correct option is: 'What, When, Why, Where'. These questions help you understand the subject matter (What), the timing (When), the purpose or motivation (Why), and the location or environment suitable for study (Where).





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Answer to Question Q2b
1. Instructions to give to experts in a Cognitive Walkthrough:
   - Ask experts to examine the interface and its interaction elements from the perspective of the users.
   - Instruct them to walk through tasks step by step as if they are new or infrequent users to identify potential usability problems.
   - Direct them to question each action required by the user, assessing if the action is logical and whether the user will know, without prior knowledge, what to do next.
   - Encourage them to articulate any assumptions they make about the user and to consider different user profiles, cognitive processes, and goals.
   - Tell them to note any points of confusion or error they predict users will encounter.
   - Request that they provide feedback and suggestions for how the user interface could be improved for better usability.

2. Information to provide to experts in a Cognitive Walkthrough:
   - A clear description of the user interface being tested, including screenshots or access to the interface if possible.
   - A precise definition of the tasks and sub-tasks that users are expected to perform with the user interface.
   - Detailed user profiles, including information on the users' experience, skills, knowledge, and demographic characteristics that could influence their interaction with the product.
   - The context in which the interface will be used, including information on any relevant environmental, technical, and social factors.
   - The goals that the users are trying to achieve with the interface.
   - Any known constraints or limitations of the system that could affect user performance.
   - Examples of real-world scenarios or use cases where the interface will be utilized to help experts anchor their examination in practical applications.





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Answer to Question Q2c
Q2c_sub1: Effectiveness - This question addresses the ability of users to learn the functions of the software.
Q2c_sub2: Efficiency - This query focuses on the time spent by users on unproductive actions which is related to the efficiency of using the software.
Q2c_sub3: Satisfaction - The likelihood of users reusing the software reflects their satisfaction with the tool.
Q2c_sub4: Efficiency - The time taken by users on their first attempt to complete a task is an efficiency measurement.





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Answer to Question Q2d
The aspect considered at this stage is 'Selectivity'. Selectivity refers to the ability of the measure to detect changes or differences specifically related to the mental workload and not to other unrelated changes or resource demands.





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Answer to Question Q3a
1. Selective Attention: This is the ability to focus on one particular stimulus while ignoring other stimuli. It enables us to concentrate on one source of information while filtering out distractions.

2. Divided Attention: Also known as multitasking, this type of attention refers to our capacity to process two or more responses or react to two or more different tasks at the same time.

3. Sustained Attention: This is the ability to maintain focus on a specific task or stimulus over a prolonged period of time. It's crucial for tasks that require extended periods of attention, such as reading or listening to a lecture.





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Answer to Question Q3b
1. Automatic decisions typically involve only working memory procedures, while controlled decisions involve interactions with both working memory and long-term memory.
2. Controlled decisions demand conscious thought.





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Answer to Question Q3c
The graphic seems to represent the components of human information processing, especially focusing on how stimuli are processed into responses with attention resources playing a role in the process. Memory and feedback are also components in this model.

Here are the labels for each numbered box:

1. Sensory Input – This is where the initial stimuli are received by our sensory organs (like eyes, ears, etc.).
2. Sensory Memory – This is a very short-term form of memory that holds sensory information. It acts as a buffer for stimuli received through the senses which are processed at a very basic level.
3. Working Memory / Short-Term Memory – Information in sensory memory may be transferred to short-term memory, where it is retained for a brief period and may be manipulated.
4. Decision Making – This stage involves making a decision on what to do with the information that has been processed, leading to some sort of response.
5. Long-Term Memory – Information from the working memory may be encoded into long-term memory, which is a more permanent store of information.
6. Feedback Loop – This represents the process by which information about the results of actions is sent back through the system to modify subsequent actions.

Attention Resources are represented as a filter or gatekeeper that allocates cognitive resources to various tasks and determine which information is processed further in the working memory and which responses are generated.

If I were to label the graphic, I would write these labels near their respective boxes.





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Answer to Question Q4a
1. Visibility of system status - The website should always keep the users informed about what is going on, through appropriate feedback within a reasonable time.
2. Match between system and the real world - The website should speak the users’ language, with words, phrases and concepts familiar to the user, rather than system-oriented terms.
3. User control and freedom - Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue.





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Answer to Question Q4b
This was a formative user study.





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Answer to Question Q4c
The NASA Task Load Index (NASA-TLX) can provide several types of results that can be used to assess the perceived workload of participants during a particular task:

1. Mental Demand: This aspect measures how much mental and perceptual activity is required. It can include thinking, deciding, calculating, and remembering. It tells us how much cognitive effort the task required.

2. Physical Demand: Refers to how much physical activity was required, like pushing, pulling, turning, controlling, or activating. This indicates the level of physical effort put into the task.

3. Temporal Demand: Measures how much time pressure participants felt due to the rate or pace at which tasks or task elements occurred. High temporal demand implies that the task required a fast pace that may increase the workload.

4. Performance: Takes into account the participants' perception of their performance. It reveals how successful participants feel they were in achieving the goals of the task and can highlight the trade-off between performance quality and workload.

5. Effort: Evaluates how hard participants had to work (mentally and physically) to accomplish their level of performance. This helps to understand if the task was easy to accomplish or if it required significant exertion.

6. Frustration Level: Assesses how much irritation, stress, and annoyance participants felt during the task. A high level of frustration could indicate a task that is unnecessarily complex or difficult, affecting the overall user experience.

These results collectively provide a comprehensive view of the participants' subjective workload experiences during the task. They can be analyzed to improve task design, interface design, or workflow efficiency, depending on the context of the study.





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Answer to Question Q4d
Q4d_sub1: The SUS method is introspective.
Q4d_sub2: The Think Aloud method is introspective.
Q4d_sub3: The measuring biometric parameters method is retrospecitve.
Q4d_sub4: The collected data from SUS are subjective.
Q4d_sub5: The collected data from Think Aloud are subjective.
Q4d_sub6: The collected data from biometric parameters are objective.
Q4d_sub7: The measured results from SUS are quantitative.
Q4d_sub8: The measured results from Think Aloud are qualitative.
Q4d_sub9: The measured results from biometric parameters are quantitative.
Q4d_sub10: The focus of SUS is on end user.
Q4d_sub11: The focus of Think Aloud is on end user.
Q4d_sub12: The focus of biometric parameters is on end user.





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Answer to Question Q5a
Continuity is one of the Gestalt principles that describes how the human eye follows elements that are arranged on a line or curve, rather than abruptly changing direction. This law implies that elements aligned in a straight line or smooth curve are perceived by the visual system as more related than elements not on the line or curve, even if they are actually separate. It suggests that the eye will follow the smoothest path when scanning elements and may perceive a continuous flow of elements rather than individual, unrelated parts.

For a web design that illustrates the law of continuity, here's how I would sketch it:

- Place a series of circles in a diagonal line across the page, with the circles at each end significantly larger than those in the middle. This creates a visual path that the eye will naturally follow from one large circle to the other. 
- Above this line of circles, have a smooth, curved line that starts and ends in correlation with the large circles. 
- Along this curved line, intersperse some text boxes or buttons that align with the curve. 
- Perhaps integrate a navigation bar at the top of the page that curves in a gentle arc, with menu items listed along this arc.

In this sketch, the principle of continuity is clear because the elements on the webpage guide the viewer’s eye in a continuous flow, rather than scattering attention in multiple directions. The curved lines and the alignment of elements encourage the viewer to naturally move from one aspect of the design to the next, creating a visual narrative that's easy to follow.





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Answer to Question Q5b
The design principle used in the excerpt of the web page is the Gestalt Law of Proximity. This principle suggests that objects that are near, or proximate to each other, tend to be grouped together by the human eye and perceived as a collective or as part of a pattern. In the graphic provided, we can see this principle at work in the way individual products are grouped together.

The design principle of proximity can be seen in how each product is paired with a label and a price immediately below it, creating a visual association between the item and its description and cost. Each of these groupings is spaced equidistantly from the next, both horizontally and vertically, which further reinforces the separateness of each product grouping. This allows viewers to easily identify and process each set of information as related to that specific product without confusion with other items on the page.





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Answer to Question Q6a
The "Power Law of Practice" describes the phenomenon where the time taken to complete a task decreases as a function of the number of practice trials. It suggests that with repeated practice, the execution of a task becomes more efficient, resulting in a reduction of the time needed to perform the task.

The formula for the Power Law of Practice is:

T(n) = T1 * n^(-b)

Where:
- T(n) is the time taken for the nth trial.
- T1 is the time taken for the first trial.
- n is the trial number.
- b is a constant that describes the rate of learning or improvement (the learning rate).





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Answer to Question Q6b
1. Mapping in design analysis refers to the relationship between the controls and their movements or effects in the system being controlled. It is about how actions or commands result in responses or changes in the system and how intuitive and clear this relationship is to the user.

2.1. Consistency: Good mapping should maintain consistent relationships between controls and their effects. For example, if a slider moves up to increase volume on one device, the same should be true for similar devices, helping the user to predict the results of their actions without confusion.

2.2. Affordance: Good mapping should suggest the correct action to the users through the design of the controls. Controls should look like they can be used in certain ways, for instance, a flat plate or a bar for pushing, or a knob for turning, making it easier for users to understand how to interact with them.





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Answer to Question Q6c
Don Norman does not recommend the principle 'Give fedback' as it is misspelled. The correct term should be 'Give feedback'. Therefore, the principle that he does NOT recommend from the given options is 'Give fedback'.





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Answer to Question Q6d
An HTA (Hierarchical Task Analysis) for purchasing a bottle of soda from the vending machine depicted in the figure would be structured as follows:

0. Purchase a bottle of soda from the vending machine.
    1. Select the soda.
        1.1. Approach the vending machine.
        1.2. Examine the soda options available.
        1.3. Decide on a soda selection.
    2. Insert payment.
        2.1. Check the price of the selected soda.
        2.2. Obtain the necessary amount of money (10 cents as indicated on the machine).
        2.3. Insert coins into the coin slot.
    3. Receive the soda.
        3.1. Press the button to dispense the chosen soda.
        3.2. Wait for the soda to be dispensed.
        3.3. Retrieve the bottle from the bottle opener area.
    4. Conclude the transaction.
        4.1. Confirm that no additional tasks are required (e.g., collecting change, if the machine provides any).
        4.2. Step away from the vending machine.

To draw this HTA, create a tree diagram where Task 0 is the root. Below it, branch out into Tasks 1, 2, 3, and 4. Each of these main branches further divides into their respective subtasks, creating a hierarchical structure of tasks and subtasks that one would follow to complete the overall goal of purchasing a bottle of soda. For a visual representation, you would have boxes or nodes representing each task connected by lines that show the flow and hierarchy of the tasks.





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Answer to Question Q7a
The difference between additive and subtractive colors relates to how colors are created and mixed:

- Additive colors are created by mixing different colors of light. This method is used in devices like TVs and computer monitors, where colors are created by combining light from red, green, and blue light sources in varying intensities. When all colors are combined at full intensity, white light is produced. Additive color mixing is based on the principle that light combines to create new colors, and when all the primary colors of light (red, green, and blue) are combined, they result in white light.

- Subtractive colors, on the other hand, are created by mixing different pigments, dyes, or inks. This method is used in processes like painting and printing, where colors are created by filtering out, or subtracting, certain wavelengths of light. The primary colors in subtractive mixing are cyan, magenta, and yellow. When these are combined, they create darker colors, and if you mix all three in perfect proportion, they ideally absorb all light and produce black. Subtractive color mixing is based on the principle that pigments in inks or paints filter out certain wavelengths of light and reflect others, thereby subtracting from the light that is seen and creating various colors.





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Answer to Question Q7b
The frequency range of human hearing is 20 Hz - 20 kHz.





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Answer to Question Q7c
1. Sensation: This initial stage involves the ear's ability to receive sound waves and convert them into neural impulses. When sound waves enter the ear, they travel through the auditory canal and vibrate the eardrum. These vibrations then move to the three bones in the middle ear (the malleus, incus, and stapes) that further amplify the sound vibrations and transmit them to the cochlea in the inner ear.

2. Transduction: In this stage, the sound vibrations are converted into electrical signals by the hair cells within the cochlea. The cochlea is filled with fluid and lined with thousands of these tiny hair cells that move in response to the different frequencies of vibrations. As these hair cells move, they create electrical signals that are sent to the auditory nerve.

3. Processing: Once the electrical signals are generated, they travel along the auditory nerve to the brain's auditory cortex. Here, the brain processes these signals so that we can recognize and interpret different sounds. The brain distinguishes between various pitches, volumes, and sound qualities to understand things like language, music, and environmental sounds.

4. Perception: This is the final stage where the processed sound information becomes meaningful to us. This is when we consciously recognize and interpret the sounds, and it allows us to respond accordingly. For instance, we can recognize a friend's voice, the melody of a song, or the honking of a car horn as a warning. Perception involves not just the physical processing of sounds but also our cognitive interpretation based on memory, experience, and context.





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Answer to Question Q7d
1. One can speak faster than one can write
2. One can read faster than one can listen





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Answer to Question Q8a
1. Interviews: This technique involves the requirements engineer asking questions to stakeholders to gather information about their needs and expectations for the system.

2. Surveys/Questionnaires: This technique uses a set of pre-defined questions to collect responses from a larger group of stakeholders to understand their requirements for the system.

3. Workshops: This involves organizing interactive sessions with various stakeholders where they can discuss and collaborate on defining the requirements for the system. Workshops often make use of group activities to facilitate discussion and creativity.





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Answer to Question Q8b
1. Time and Cost: High-fidelity prototypes are generally more time-consuming and expensive to create due to their complexity and the level of detail they require. In contrast, low-fidelity prototypes are quicker and cheaper to produce as they can be made with basic materials and do not require extensive functionality.

2. User Engagement: High-fidelity prototypes provide a more accurate representation of the final product, which can be more engaging for users and stakeholders during testing, as it gives them a better sense of what to expect. However, because low-fidelity prototypes are more abstract and less detailed, they may lead to a lack of user engagement or difficulty in visualizing the final product.





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Answer to Question Q8c
1. 'User stories are used to understand the needs of users.' - True. User stories are indeed utilized to comprehend what the users require from the system, making it a key aspect of scenario-based design.

2. 'Conceptual scenarios are a good start for prototyping.' - True. Conceptual scenarios describe possible use situations for the system, which can help in forming a starting point for creating prototypes.





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