Hello,
I normally use eye-tracking metrics computed automatically by Tobii Studio. When looking at the raw data, however, I noticed that even events classified by the filter (Tobii I-VT) as fixations may have a validity code of 4 (no eye found) for both eyes. These events seem to be rare, but I wonder why the filter classified them as fixations if no eyes could be found. My main doubt here is: are these fixation events coded with 4 for both eyes taken into account in fixation metrics produced by Tobii Studio?