Creating Blocks
The next step is to define an expt element that defines the flow of blocks in the experiment. The expt element is defined as follows:
<expt> / preinstructions = (intro) / postinstructions = (end) / blocks = [1=up_practice; 2=block2; 3=block3; 4=block4; 5=block5] </expt>
The expt element is simple. The preinstructions attribute begings the expt by showing subjects a page of instructions, "intro". The postinstructions attribute specifies final instruction page named "end" to be displayed at the conclusion of the experiment. The blocks attribute specifies a total of 5 blocks. The first block is the "up_practice" block in which subjects practice classifying the pleasant and unpleasant stimuli. Blocks 2 through 5 are set to between-subject variables named "block2", "block3", "block4", and "block5", all of which are defined below. These between-subject variables allow the experiment to counterbalance the order in which the test blocks are run across subjects.
Next, we'll define the between-subject variables used above:
<variables> / group = (1 of 2) (block2=fi_practice, block3=incompatible, block4=if_practice, block5=compatible) / group = (2 of 2) (block2=if_practice, block3=compatible, block4=fi_practice, block5=incompatible) </variables>
The variables element defines between-subject variables based on the subject number that was entered when the experiment is run. The first group attribute specifies the variable values for odd numbered subjects. For odd-numbered subjects, block2 is fi_practice, block3 is incompatible, block4 is if_practice, and block5 is compatible. For even-numbered subjects, block2 is if_practice, block3 is compatible, block4 is fi_practice, and block5 is incompatible.
With that, the script is essentially complete. However, we'll do a little fine tuning by specifying some default settings using the defaults element.
<defaults>
/ screencolor = (175, 175, 255)
/ fontstyle = ("Courier New", 14pt)
</defaults>
The screencolor attribute sets the color of the screen throughout the experiment to light blue. The fontstyle attribute specifies that all stimulus and instruction text should be displayed in a 14pt Courier New font. You can specify the font attribute using Inquisit's Font Wizard, avaiable from the Tools menu. The wizard allows you to pick a font using the standard font dialog, and will spit the corresponding attribute definition into your script.
The experiment is now complete! You can run the experiment by selecting the "Run" command on the "Experiment" menu.
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Creating Blocks
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