Dynamic Lighting & Darkvision with Light Sources

Individually, all of the characters have dynamic lighting working the way I'd expect. Those with darkvision see what they should see; those with lanterns and torches see what they should see. But, when I put someone with darkvision along side someone with a torch, the person with darkvision still sees 60 ft. I would expect/hope their darkvision would be overcome by the torch and their vision would drop down to 40 ft. Is this possible in Roll 20? And if so, how do I make it work? Thanks, PAlterBoy

Short of some serious API scriptomancy (calling The Aaron...), no, this isn't possible. R20 doesn't know when tokens are close to one another, so there's no way to adjust vision automatically like this.

I don't know what system you use, but does Darkvision not typically work in conjunction with a torch anyway, rather than being disabled by it? 

Dynamic lighting doesn't ‘know' what dark vision is. It can only go by the settings you input to control vision and light. The interaction with other tokens is limited to sharing vision (by sharing control) or sharing light (set in the tokens lighting options). It might be possible to write an API script to provide proximity-based vision changes, but it's not within the normal game controls.

Confirmation, it would be possible with the API, if something of a pain in the butt.  =D  You'd need a Pro subscription to take advantage of it though, and someone would need to write it.

Thanks everyone! Knowing it's not possible without serious scripting at least will stop my, "hmmm, what if I try this?", and "maybe if I try that?" attempts.  Dusky - I'm using D&D 5E. There is some debate amongst scholars as to whether a light source interferes with darkvision. I was mostly hoping to experiment in Roll20 and then decide whether to apply a rule that it did/didn't. Given what I've learned from the posts above, that decision has pretty much been made for me! :-)