Get the Data

Chiasm returns gaze data as an array of prediction objects. Each object contains a unique frame ID, a timestamp (in milliseconds), and the predicted gaze coordinates on the screen. If you provide an eventId, it is included as well:

[
  {
    "frameId": "15813239-5902-404d-acf6-fd3c784a1cce",
    "timestamp": 132724,
    "x": 692.23,
    "y": 581.55
  },
  {
    "frameId": "1011fe71-61f8-4e2c-bfa9-3927a313bc1a",
    "timestamp": 132757,
    "x": 723.48,
    "y": 562.01,
    "eventId": "stimulus_onset"
  },
  {
    "frameId": "709d98ff-5c1c-4300-bec4-8cfc689b0a26",
    "timestamp": 132795,
    "x": 734.27,
    "y": 563.36,
    "eventId": "stimulus_onset"
  }
]

Field	Description
frameId	Unique identifier for each captured frame
timestamp	Time in milliseconds since the recording started
x	Predicted horizontal gaze position (pixels)
y	Predicted vertical gaze position (pixels)
eventId	(optional) User-provided label for tagging frames with experiment events

Gaze predictions are always returned as a response to the calling code — there is no separate data endpoint to configure. The saveData parameter in setExpInfo controls whether a copy is also saved to the Chiasm dashboard.

Option A — Response only (saveData: false)

When saveData is set to false (the default), gaze predictions are returned in the response to your calling code but not stored on Chiasm servers.

tracker.setExpInfo('YOUR_EXPERIMENT_ID', 'YOUR_PARTICIPANT_ID', false);

After startRecording, predictions come back directly in the response. You can then store or process them however you like — no additional routing or endpoint setup is needed.

Option B — Response + dashboard (saveData: true)

When saveData is set to true, gaze predictions are returned in the response and a copy is uploaded to the Chiasm servers.

tracker.setExpInfo('YOUR_EXPERIMENT_ID', 'YOUR_PARTICIPANT_ID', true);

You still receive the data in your code exactly the same way, but you can also:

1. Open your experiment in the Chiasm dashboard.
2. Browse individual participant sessions.
3. Download the gaze data as CSV files for analysis (contact us so we can provide a private link)

Which should I choose?

	Response only (false)	Response + dashboard (true)
Data returned in response	Yes	Yes
Data saved to Chiasm	No	Yes
Dashboard access & CSV export	No	Yes
Best for	Custom pipelines, strict data-residency requirements	Fast setup, backup copy

Next Steps

• Custom Code tutorial — full walkthrough for a vanilla JavaScript experiment
• setExpInfo reference — details on all parameters
• startRecording reference — how gaze data is captured during a session