The paper discusses the concept of response time in human-computer interactions, emphasizing that it varies based on the user's purpose and the context of the task. It defines "need" as a better alternative in a set of competing options that enable a human purpose. The paper explores two major types of needs: operating needs, which are essential for the system's function, and psychological needs, which relate to the user's expectations and mental state. Psychological needs are influenced by the user's expectations and the sense of closure during tasks. A "closure" is a feeling of completion that allows users to tolerate delays after the task is completed. The paper also discusses the role of short-term memory in task performance, noting that delays can lead to frustration and errors. It suggests that response times should be limited to two seconds for most tasks to maintain user engagement and mental continuity. The paper highlights that response times should be considered in the context of the user's mental state and the nature of the task. For example, a two-second response time is generally acceptable for simple tasks, but longer delays may be necessary for complex tasks. The paper also discusses the importance of immediate feedback for tasks that require continuous interaction, such as conversations or problem-solving. The paper provides specific response time guidelines for various types of interactions, including system availability, task completion, and information retrieval. It emphasizes that response times should be tailored to the specific task and user needs, and that delays longer than two seconds can significantly impact user experience and task efficiency. The paper concludes that response times should be designed to maintain user engagement and mental continuity, with exceptions for tasks that require longer delays.The paper discusses the concept of response time in human-computer interactions, emphasizing that it varies based on the user's purpose and the context of the task. It defines "need" as a better alternative in a set of competing options that enable a human purpose. The paper explores two major types of needs: operating needs, which are essential for the system's function, and psychological needs, which relate to the user's expectations and mental state. Psychological needs are influenced by the user's expectations and the sense of closure during tasks. A "closure" is a feeling of completion that allows users to tolerate delays after the task is completed. The paper also discusses the role of short-term memory in task performance, noting that delays can lead to frustration and errors. It suggests that response times should be limited to two seconds for most tasks to maintain user engagement and mental continuity. The paper highlights that response times should be considered in the context of the user's mental state and the nature of the task. For example, a two-second response time is generally acceptable for simple tasks, but longer delays may be necessary for complex tasks. The paper also discusses the importance of immediate feedback for tasks that require continuous interaction, such as conversations or problem-solving. The paper provides specific response time guidelines for various types of interactions, including system availability, task completion, and information retrieval. It emphasizes that response times should be tailored to the specific task and user needs, and that delays longer than two seconds can significantly impact user experience and task efficiency. The paper concludes that response times should be designed to maintain user engagement and mental continuity, with exceptions for tasks that require longer delays.