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Multiple Stages

By default, an entire jsPsych experimental timeline is constrained to one page, /app/experiment.html. Though this should be fine for most experiments, this may be less than ideal for experiments with multiple stages or tasks.

For example, imagine an experiment involving two tasks: a Stroop task and a gambling task. If these two tasks are combined into one jsPsych timeline and served via /app/experiment.html as usual, then an experimenter might run into a few problems. First, the data will only be saved at the end of the time – that is, the data for the Stroop task will only be saved when the gambling task ends. It might preferable for the data to be saved at the end of each respective task. Second, any restart or refresh events will start over the entire experiment – even if the participant already completed the first task. It would instead be preferable for the timeline to start at the first unfinished experiment.

It is possible to extend NivTurk to have multiple experiment pages (e.g. one per task). Doing so, however, requires reconfiguring the Flask routes by which participants are moved from page to page. The required changes are numerous but relatively straightforward.

A complete minimal example (based on the Prolific branch) is available for inspection in the multi-stage branch of NivTurk. In brief, the routes in /app/ are duplicated for each new stage of an experiment.

Integrating standalone NivTurk experiment

To integrate a standalone NivTurk experiment/task into this multi-stage version, a general outline of changes can be referenced below:

  • In /app/static/templates/main.html/:
    • check ordering of experiments
    • enter task name
    • enter estimated time
  • Add /app/static/templates/experiment/task.html file to /templates/experiments folder
  • In /app/
    • add decorators and routing:
      def task():
  • In /app/static/templates/experiment/task.html or corresponding data saving file for task
    • edit saving and redirecting:
    • make sure to use the on_success function rather than redirect_success, and change input parameters
    • check and edit for redirect_reject
  • Linked files:
    • Go through list of linked files in task.html: (reminder to rename or create task specific subdirectory if different versions are used by the different stages)
      • css:
        • add to /app/static/css directory
      • jspsych plugins:
        • add to jspych plugins folder under /app/static/lib
      • other js files
        • add to /app/static/js
    • images:
      • add task preview image to /app/static/img/main
        • make sure to name the files to have the same name as task
          • eg. for effort task: effort.png
        • create and add other task specific images to app/static/img/task folder
          • add attribution if necessary
      • Since task.html is now in the /experiment folder, add ../ to appropriate paths in task.html