(a) Explain the following principles in HCI (6 Marks)i. Affordanceii. Usabilityiii. Visibility(b) Discuss three main goals of HCI. (3 Marks)(c) Compare the constructivist and ecological theories of perception and give examplesof how each has influenced interface design. (4 marks)(d) Describe, with the aid of a diagram, the Human Information Processing model.(5 marks)(e) Explain between knowledge in the world and knowledge in the head. (2 Marks)(f) (i) Differentiate “recognition rather than recall” as used in HCI (2 marks)(ii) Discuss areas in system design where ‘recognition’ is encouraged (2 Marks)(iii) Discuss areas in system design where ‘recall’ is encouraged (2 Marks)(g) Discuss any two metaphors used in the study of HCI and clearly show theirimportance in system design. (4 marks)

(a) Principles in HCI: i. Affordance: This refers to the potential actions that are possible, but not yet performed by the user. For example, buttons on a website are designed to suggest clicking. ii. Usability: This refers to how easy and efficient a system is to use. It includes factors like ease of learning, efficiency of use, memorability, error frequency and severity, and user satisfaction. iii. Visibility: This refers to the ability to see and understand the state and possible actions of a system. For example, a well-designed website will make it clear what actions are possible and what is currently happening.

(b) Three main goals of HCI: i. To improve the usability of systems. ii. To make systems more accessible to a wider range of users. iii. To make systems more efficient and effective in achieving user goals.

(c) Constructivist vs Ecological theories of perception: Constructivist theory suggests that we construct our perception of the world based on our experiences and expectations. For example, a website might be designed with familiar icons and layouts to match user expectations. Ecological theory, on the other hand, suggests that our perception is directly influenced by the environment around us. For example, a mobile app might be designed to take advantage of the way we naturally interact with our phones.

(d) Human Information Processing model: This model describes how humans process information. It includes stages like encoding (taking in information), storage (keeping information in memory), and retrieval (accessing and using stored information). A diagram would show these stages as a flowchart.

(e) Knowledge in the world vs knowledge in the head: Knowledge in the world refers to information that is available in the environment around us. For example, a user manual or help guide. Knowledge in the head refers to what we have learned and remember. For example, knowing how to use a software without needing to look up instructions.

(f) Recognition vs Recall in HCI: i. Recognition refers to identifying something you have seen before, while recall involves retrieving information without any cues. In HCI, recognition is often easier than recall. ii. Recognition is encouraged in areas like menu design, where users can choose from visible options. iii. Recall is encouraged in areas like command line interfaces, where users must remember specific commands.

(g) Metaphors in HCI: i. The desktop metaphor: This represents files and actions in a way that mimics a physical desktop, making it easier for users to understand and interact with the system. ii. The journey metaphor: This represents a process as a journey, helping users understand where they are in the process and what steps they need to take next.