PsychoPy · to publish
Beads task
In the beads task a participant watches beads drawn one at a time from a hidden jar and says, whenever they are ready, which of two jars it is. The usual number reported from it is draws to decision: how many beads someone needed before committing. People with delusions tend to need fewer, which is where the jumping-to-conclusions literature comes from.
Draws to decision throws away most of what happened. It collapses a sequence of beliefs, each formed after a specific piece of evidence, into one integer. A model of belief updating needs the sequence, not the summary, so this implementation logs every draw: what was shown, when the response came, and what the participant reported believing at that point.
That is the only real design decision in it. The task itself is old and the implementation is not clever. What it does is refuse to reduce the data at collection time, when the reduction cannot be undone.
It feeds the HGF pipeline and runs in the schizophrenia thesis. It is not public yet.