Virtual Chinrest calculations Check

[Cluster-Bomb]

Hi there,

I've had trouble with setting and quite frankly understanding resize parameter and making it function with degrees of visual angle. As a work around - I used the method below. Based on this method I have two questions:

1. Will the below method give me the same stimulus size on various monitor resolutions using the virtual chinrest plugin?
2. Can somebody tell me if there is a easier way to achieve this with the plugin?

I'm trying to replicate a study that has a stimulus height of 5 degrees of visual angle. Using the close approximation formula of tanV = S/D - and assuming a viewing distance of 680mm (how close I generally sit to the computer) - I get a stimulus height of 62mm (rounded to nearest mm).
Using an online calculator - I got a dpi for my display of 72 - and based on that the calculator gave a px conversion of approx 176px for a stimulus of 62mm.

So I am assuming that if I set the base ratio of px for unit in the virtual chinrest and I have the right stimulus size - then the plugin with vary the px per unit to maintain original stimulus size in px.

So I set the parameters of the plugin to the following:

resize_units: "cm"

pixels_per_unit: 28 (176/6.2)

I then set my stimulus sizes in the video_keyboard_reponse plugin to a height of 176px.

Cheers
Sean