Randomization of stimuli for each group in Pavlovia shelf

Online experiments
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9

Here’s my tip on using the Pavlovia Shelf

At the start of the experiment you need to retrieve the list for the current group.

// Retrieve the value of a dictionary field in a Shelf entry
fieldValue = await psychoJS.shelf.getDictionaryFieldValue({key: ["shelfName"], fieldName:"fieldName", defaultValue:"fieldName not found"});

fieldValue in this case will be your list of 10 images

You will also need a list of image indices.

imageIndices = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
shuffles(imageIndices)
useRows = []
for Idx in range(10):
    if fieldValue[imageIndices[Idx]] < 5:
        fieldValue[imageIndices[Idx]] += 1
        useRows.append(imageIndices[Idx])
    if len(useRows) == 5:
        break

This should give you a list of rows to select which are a random choice from your ten images with a maximum of 5 presentations of each within each group.

Then update the shelf at the end of the experiment

// Update the value of a dictionary field in a Shelf entry
await psychoJS.shelf.setDictionaryFieldValue({key: ["shelfName"], fieldName: "fieldName", fieldValue :fieldValue});