Mental model of the user in transactional processing systems

Based on the analysis of the user’s mental model in interfaces implemented in transactional environments, the basic elements of a new object-action interface and the necessary technological architecture are proposed.

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Abstract: Based on the analysis of the user’s mental model in interfaces implemented in transactional environments, the basic elements of a new object-action interface and the necessary technological architecture are proposed.

Can a transactional processing system really have a user interface oriented to object-action interaction?

I myself answered this question in the affirmative in my last article, although I made it clear that the solution requires a change in technological architecture. I maintain that the dominant technology in transactional processing systems forces us to create user interfaces with the action-object interaction model, which entails a series of usability problems.

In this article I make a transactional architecture proposal aimed at supporting an object-action user interface. To do this, I start from the analysis of the user’s mental model in transactional environment interfaces, I describe the basic elements of the new object-action interface and, finally, I propose the necessary technological architecture to make this interface viable.

user mental model

To drive a car we do not need a great knowledge of its engineering, it is enough for us to know that it has an engine that drives it and that, from time to time, it is necessary to add gasoline. Likewise, when we buy a book on Amazon, it is enough to know that behind the cable that connects us to the network there is a central computer that will collect our order and that it will only process it if we enter a credit card number.

People form an idea of ​​how systems are and how they work when we interact with them, be they computers or other devices. It is not an exact image of reality, it is just an imprecise idea that helps us make them work. This mental idea is called the “user’s mental model.” Donald Norman explains it in detail in his book The Psychology of Everyday Objects.

Mental model of the user in classic interfaces of transactional processing systems

Mental models for WIMP interfaces (windows, icons, pop-up menus and pointer) and for Web interfaces have been extensively studied (see Dick Berry’s interesting article). On the other hand, it is very difficult to find studies that talk about the mental model in the interfaces implemented in transactional processing systems.

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The user mental model for these interfaces can be described as follows:

1. Elements that compose it:

  • Terminal with screens containing buttons, menu options, and forms with labels and fields for entering data.
  • Remote central computer that processes the information. This distant computer idea is a very powerful concept in the mind of the user.
  • Information that travels through the network with the data that the terminal sends to the central computer.
  • Responses from the central computer to the terminal, usually in the form of text.

2.Space:

  • Space beyond the control of the user. For him, the data is in an inaccessible space.
  • Finite space limited by a specific theme: books, trips, stock market, etc.
  • Identified owner to whom to claim, who protects the information.
  • The user perceives independence between his interface (PC, web, mobile, etc.) and the central computer, which allows him to maintain the same mental model even though the interface is different in each channel.

3.Forms of presentation:

  • The user perceives that the forms of presentation are different depending on the channel in which they are operating: self-service, mobile, web, financial terminal, etc…

4.Navigation:

  • The user has the feeling that the navigation is fully guided, since there is no option to change the flow of the dialog.
  • The user, depending on the channel where he is operating, may find one of the following navigation systems:

    a) Menu navigation.

    b)Dialogue guided step by step, very typical of self-service terminals and web environments.

5.Interaction:

  • Perception of connection and disconnection: the user has the feeling that, from the moment he sends the information until he receives the response, there is a connection time during which control is handed over to the central computer.
  • The user interacts with the interface within temporary short work units, in which the main objective consists of the introduction of data to be sent to the central computer.
  • The interaction in these work units almost does not require graphical interface mechanisms (drag & drop, double click, etc.). The user only expects to enter information, select options and click action buttons.

6.Response time:

  • Adaptation to the channel: the user adapts to the usual response time of the channel in which he is operating. For example, in a web form, you will accept a longer response time than in a self-service terminal.

Shift to an object-action mental model in transactional process system interfaces

In the user’s mental model exposed so far, there is no concept of a manipulable object. The user knows what tasks he wants to perform and, to do so, he must select actions, fill out forms and send information to a “central computer” from which he expects to receive responses.

But if we want to go from a style of menus and forms to a style of object-action interaction, we must create a new interface with which the user can build a mental model that:

· Be consistent with object manipulation.

· Keep certain elements of the previous model: central computer, connection and disconnection, etc.

· Replace elements of the previous model: work unit, menu navigation, etc.

New aspects to take into account for this new interface

Metaphors: give the user a context, a space in which objects make sense. These are analogies with the real world that help to recognize objects, their properties and their behavior. The most classic case of metaphor is that of the desktop, used in most operating systems with a graphical interface: Apple, Windows, etc.

Objects: they are part of the metaphors. They must be tangible. In the case of a book sales office, for example, the objects could be: book, author, catalog…

Behavior of objects. Each object must have defined and expected behaviors. For example, the “catalog” object, when opened, should display the “book” objects it contains.

Visibility of the actions that the user can do on each object and also visibility of the limitations that indicate what they cannot do.

Control of personal space. The user must be able to clearly understand and separate which is the space that he controls and which is the space that he yields to the control of the central computer.

Predictability of the scope of your actions. The user must be able to foresee which actions will cause a permanent modification of the data and which will not.

Reversibility of actions. The user must be able to easily override the result of his actions. This is what will allow free exploration and testing without fear of making irreversible errors.

Technological architecture change proposal

The basic technological architecture of a transactional processing system is based on a two-layer Client-Server model in which the server layer is a remote system and the client layer is very light, that is, it has almost no capacity to execute transaction logic. app. In a basic transactional model, all dialog processing and management is performed at the server layer.

Below I propose the changes and new elements to add to this architecture:

1.Control of events and execution of logic associated with the data model in the client layer: this will allow the interface to contain objects with their own behavior.

2.Maintenance of object-oriented data context in an intermediate layer to allow the user to have a space controlled by himself.

3.Place the dialog logic in an intermediate layer, allowing the user’s actions not to affect the server’s data. This helps to improve the reversibility of user actions.

4.Hypertransactions that are translated into groups of simple transactions, with the aim of facilitating the updating of server data from the objects located in the intermediate layer.

5. Translator from the logical model of objects to the physical relational model, possibly located in the server layer or in a new intermediate layer. This translator is based on a system of equivalences between the existing objects in the user interface and the relational databases of the servers.

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