Computers have now become an essential part of the experimental psychology laboratory. In a previous paper, the advantages of using PsyScope, a graphical tool for designing psychology experiments were discussed (Roche, Stewart & Barnes-Holmes, 1999). The primary advantage identified was PsyScope’s graphical user interface which is much more user-friendly than traditional programming languages. On balance, however, PsyScope is restricted to the Macintosh platform, is now no longer under development, and certain features such as drag & drop functions, are not available. As time passes, therefore, PsyScope may become increasingly obsolete. Fortunately, these issues can be addressed readily by turning to the use of Visual Basic (VB). This is a modern programming language that combines the use of a graphical user interface with the easy-to-learn BASIC programming language (see Bishop-Clark, 1998), and as part of Microsoft’s ongoing development plans VB obsolescence is not an issue in the short to medium term. The key advantage to VB is that it provides the power and flexibility of PsyScope using the PC platform. Furthermore, VB can also be used on a Macintosh using standard Macintosh-PC emulators, whereas attempts in our laboratory to use PsyScope on a PC using a Macintosh emulator were unsuccessful.

The use of VB has been reported in a number of articles (Beaty, 1999; Dunham, Sherba & Rutherford, 1996; Pelechano & Darias, 2000; Saeki, Uchida & Ito, 1998). In the current paper, we will provide some relevant examples that will illustrate some of the main characteristics of VB, that make it perhaps the most useful tool available to behavior-analytic researchers for developing computerized experimental control.Footnote

Those readers who remember the BASIC programming language will recall that the program consisted entirely of lines of symbolic instruction code (e.g. if x=10 then y=0). Any graphics or mouse control events required quite complex programming skills. In contrast, VB consists primarily of individual blank pages (called “forms”), upon which various common controls are presented, such as buttons, text boxes and picture frames. Stimuli can easily be placed on these and other types of controls, which may be then activated within the program to record either mouse clicks or button presses.

Example 1: Creating a Simple Matching-to-Sample Task
The first example will illustrate the process of writing a simple matching-to-sample task using VB. Figure 1 shows the typical arrangement of tools in the VB programming environment. Forms are displayed in the center of the screen, a tool bar containing all available controls is placed on the left side, and properties for each control can be found on the right side. For example, having placed a button on the form, the color of this button can be changed by selecting the appropriate property (see below).

In the first step of our example, “New Project” is selected from the “File” menu. A new project file is generated by the computer, including a blank form that will contain all the stimuli. The label control (used to display text) is selected in the tool bar, and four labels are created and each placed in the desired position using the mouse (like in any drawing program): one on the top of screen, one in the center, and two at the bottom. The names of these labels will be changed using the Properties Window (by clicking on the Name property): the top label is named Sample, the center label Feedback, the left bottom label ComparisonLeft and the right bottom label ComparisonRight. Other properties that might be changed are the size and type of the font, the color of the text or the background, and so forth. Finally, the text displayed in each label is also changed using the Properties Window (by clicking on the Caption property). Text in the Sample label is set to “A1”, text in the ComparisonLeft label to “B1”, text in the ComparisonRight label to “B2”, and text in the Feedback label to a blank space.

Thus far, all of the work has been done using the graphical user interface. The next step is to write the code that will control the program. The sample was A1, so ComparisonLeft (B1) is the correct comparison. To insert the code, the ComparisonLeft label is double-clicked, which opens the Code Window associated with this control. Every instruction written here will be executed when the ComparisonLeft label is activated by a mouse click (code for other events can be added, as in the case of pressing a key or moving the mouse over a control). Comments written after the inverted comma at the end of each line explain what each line of code does within the program: