I am currently analysing some eye tracking data which I recorded in the lab.
For my fixation density maps I calculate tables showing the number of times participants made a fixation at a specific coordinate on the screen. I then filter them with a gaussian filter (with the matlab function imgaussfilter), however I am not sure how to choose sigma sensibly. I would like to adapt to a paper I based my experiment on. In the paper they used a '2D circular Gaussian Kernel with 0.5° full width at half maximum'. I am not fully sure what this means. Does degree mean visual degree? How can I transfer this to my analysis?