FAQ: How do I incorporate practice and experimental trials into the same Data Source?

[SR-SUPPORT]

You can include both practice and experimental trials within a single Data Source by using a combination of Blocking Levels and the Split by property. This allows you to present practice trials first, followed by your main experimental blocks.

The example below shows the Data Source columns from the Picture Response example from the Experiment Builder Video Tutorial Series: 

1. Step 1: Use "Blocking Levels" to Separate Trial Types
   First, use blocking to group the practice and experimental trials.
   
   1. Create a "Status" Column: In your Data Source, add a column to define the trial type (e.g., name it practiceStatus). For each row, label it as either practice or experimental.
      
   2. Set Blocking Level: Go to the Randomization Settings for your Data Source. Set your practiceStatus column as the first (highest) Blocking Level.
      
   To ensure practice trials are always presented first, you must also do the following:
   • Order the rows: Place all practice trials at the top of your Data Source, above the experimental trials.
     
   • Disable Randomization: In the Blocking Levels settings, uncheck the Randomize option for the practiceStatus level. This forces Experiment Builder to present the blocks in the order they appear in the Data Source.
     
      
   
   
2. Step 2: Use "Split by" to Control Block Length
   Often, you will have a different number of practice trials than experimental trials, and you may want to show an instruction screen between blocks. The Split by property is used for this.
   
   Found in your TRIAL sequence's properties, Split by determines how many trials run before the experiment flow returns to the parent sequence (e.g., the BLOCK sequence). You can place instruction screens in this parent sequence to have them appear between your blocks of trials.
   
   For example, you could set up your Data Source to specify the number of trials per block (e.g., 2 for the practice block, and 8 for each experimental block) and use the Split by property to control the flow accordingly.
   
      

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Further Resources
For a more detailed guide on these features, please see the following resources:

• Video Tutorial: Randomization Options
  
• Webinar: Data Source Randomization