• The user is given sufficient information for task completion.
• The user can control the pace of interaction with the user interface.
• The user can correct errors easily.
• The user is given feedback about the current state of the task.

2) User Psychology   In order to design a good interface that users can relate to, we must understand some of the psychological traits that a user has. Some of the traits are listed below. Context Short term memory Long term memory Working memory Variable pacing Closure Chunking 1) Context Because of the different languages and dialects across the world, we have to take into account the language that is able to get the idea and message to the user using the software system being developed. 2) Memory There are three basic types of memory, namely Ø Short term Ø Long term Ø Working memory 3) Short-term memory Consists of things that we are thinking of right now. The items in short-term memory do not need to be recalled by association or conscious. Generally, short-term memory is thought to be limited to about 7 distinct items and it will not store an item for more than a few seconds. This means that the user must lead the user in a gradual flow, requesting data and decisions that are closely associated with the previous data and decisions 4) Long-term memory This stores our “real” memories, things that we have memorized and recall, more or less at will. Accessing information in long term memory may result in significant delays. Therefore, user interface should not exploit too much of this memory. 5) Working Memory This is the part of the memory that users employ for planning, problem solving and decision making. We must also bring upon the idea of recognition and recall, which is similar to short-term and long-term memory. Research has shown that recognition is twice as effective as recall. For this reason, user interfaces that provide direct manipulation or at least, menus or prompts are more user-friendly than interfaces that depend on the user to formulate commands on his own. 6)Variable placing When designing interface, we have to consider the user’s need for slower pace during thoughtful as opposed to routine tasks. Also there is a need for software to adapt to the level of sophistication and experience of the user. Good user interfaces take care of the user’s ability to pace, to control and to interrupt the flow of interaction. 7) Closure This is the degree to which some actions just completed represent the end or closure of a task. One of the most disconcerting things software can do to people is to delay response to an action far beyond what seems reasonable in terms of the sense of closure they feel. By rule of thumb, -the amount of closure increases with task complexity. -The delay of closure tolerated increases with task complexity. 8) Chunking Chunking or organization is the principal technique that we use to allow us to deal with more information in our environment that we can handle. Basically, organization means grouping individual items of information logically, then placing the group in our mind with a name of the group. The name is much easier to remember and from it , the entire group can be reconstructed. 3)  Selection of the type of User Interface   There are three basic types of user interfaces Command interfaces Direct manipulation interfaces Menu interfaces After considering the requirements given by the client, we have decided to use a menu interface. Reasons for choice of menu interface With reference to our software requirements, Typing effort is kept to a minimal for the user. User are always presented with a valid command list from which they can select from User errors are trapped by the interface. If an incorrect menu selection is made, the systems indicate that the selection is invalid and that the user should make another choice. There are basically three types of menu selections Full-screen menu Walking menu Hierarchical menu We have decided to use the full-screen menu. On command from the user, the next set of choices is displayed. Reason for choice of full-screen menu For full screen menus, choices are typically organized linearly and these menus may be scrolling or non-scrolling. Menu options are linearly arranged but without the scrolling. This menu suits our interface because we need to design an interface that users can choose the parking lot and the time needed. Also, they are also given the path to their parking lots.   Hosted by www.Geocities.ws