Trial Randomization + Inter-block Break -

Builder
1

OS: Windows11
PsychoPy version: 2026.1.3
Standard Standalone Installation? y
Do you want it to also run online? n

Hi, I’m building a backward masking task in PsychoPy Builder and need help setting up trials and blocks.

My task is running successfully with a single sequential trial. However, I think I need to use a block loop in order to randomized trial stimuli and to add an inter-block break.

Structure of task

  • 18 blocks, 8 trials per block (144 trials)
  • Trials within each block should be presented randomly
  • Response screen after each trial
  • 16 second inter-block blank screen after the 8th trial response screen
  • Next block begins automatically
  • Blocks should run sequentially (there’s a fixed order to the blocks)

If possible, I do not want to split the excel file into 18 separate files.

I’ve looked into several Youtube videos and it seems like I may need to use a Code Component to select specific rows from a single conditions file (e.g., rows 0–7 for Block 1, rows 8–15 for Block 2, etc.). I’ve only used Builder’s interface, so I’m hoping someone can offer a beginner-friendly explanation / resources with where the code components need to be inserted and what code is required.

Any advice is appreciated, thank you!!

2

Do you definitely want the 18 blocks to run sequentially? If so then you could use concentric loops where outer_loops has nReps = 18 and the inner trials loop has selected rows $useRows. Then add a code component in a routine that is in the outer_loop but before the trials loop starts with the following code in Begin Routine

useRows = str(outer_loop.thisN * 8) + ":" + str(outer_loop.thisN * 8 + 8)