I want to combine fNIRS and eye tracking to study autism, but since they have a different sample rates, and eye tracking is much more faster, so how to synchronise them？
Our software package, EventIDE (www.okazolab.com) can alone handle all functions that you need. That would include stimulus presentation, eye-tracking recording (with any eye-tracker mode) and synchronization with fNIRS (up to millisecond precision). In addition, you can monitor and process eye-tracking data and brain signals in real-time, for example, allowing stimulus adjustment based on instant brain-eye coherence, as Adam suggested.
It depends of course on what system you are using and in how far the manufacturer supports a tight integration of the two techniques. Generally, you can think of simple things like covering both the infrared camera of the eyetracker and the receiver optode to get an estimate of the delay and jitter between the two devices. Note that this is always limited by the, usually, low sample rate of fNIRS. This means, if your NIRs device samples at say 10Hz, then a delay of one sample is already 100ms. Generally, this is not a problem for fNIRS as the hemodynamic response is in the order of 5-10 seconds anyway, but if you want a better synchronisation such a calibration procedure should be done.
In addition there can be software solutions. For example, we work together with Biosigma, a software company that also focuses on eye tracking and data integration, and Tobii, the famous eyetracking company. For more information see http://www.artinis.com/eye-tracking-devices/ and our recent blogpost about combining NIRS with eyetracking: http://www.artinis.com/blogpost-all/nirs-and-eye-tracking
Note that there will always be an imperfect synchronisation if it is just done via combining data streams on only the software side. I dare to say that a manufacturer's synchronisation would be more precise though, as they know the inherents of the specific system better than anyone else - at least we think so for our devices ;) But as said, that does not have to be a problem, especially for NIRS, as the hemodynamic response is sluggish anyway.
Should you have more questions, feel free to contact us at [email protected]
- Badges
- Science topic
- Similar topics
- Psychology
- Cognitive Science