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The Mind-Trace platform allows testing of stimuli directly from a participant’s web browser. In order to present the right stimulus at the right time, the presentation software running in the participant’s browser needs a protocol file. This file can be down- or uploaded through the API. The experiment editors in the Customer Portal will also modify the protocol file.

The present document outlines the file format used for the protocol, and details all available presentation options. Note that under normal circumstances a protocol is generated by the Customer Portal.

Protocol files are in the JSON format, the root element is an ordered list of stimuli. A stimulus is a JavaScript object consisting of unordered key/value pairs. Every stimulus requires a “type” key which can have of the following (case-insensitive) values:

  • Calibration – Defines the calibration procedure to be used.
  • Image – Present a single image
  • Redirect – Redirect to another website
  • Section – Group multiple stimuli together
  • Video – Present a single video
  • Vimeo – Present a video hosted on Vimeo
  • Web – Show a web-site (experimental)
  • YouTube – Present a video hosted on YouTube

Depending on the stimulus type, other keys may be present. The stimulus types are documented in the next section.