I wonder what you mean by "concern for human rights": is it human rights problems? enforcement? human rights as a political issue? human rights as an approach to public action? human rights as portrayed in the media?

Who would these respondents be? Experts, activists, general public?

You may need to develop a scale from scratch if one does not exist already. There is a chapter in my dissertation on scale development, which is availble on my Research Gate page.

Peter Singer touched on this question somewhat in his essay 'Animal Liberation', in which he explored the idea that typical people might not want animals to suffer, but their own wellbeing would obviously come first. Which is to say a good way of gauging a persons willingness to sacrifice comforts or enjoyments would be a place to start. As oftentimes the root of large animal welfare issues stems from industrialized meat industries that seek to ensure demand is met by further commoditizing animals, taking a living thing and viewing it strictly as a product. If an individual is willing to give up certain meats, regardless of their predilections, because of their concern for animal welfare; then their ability to sacrifice personal conveniences would prove an adequate measurement of similar concerns.

The situation above is more aimed at large scale agricultural issues, but it really applies to any situation involving choices society faces between protecting animals and expanding upon human agenda.

I hope that helps!

Relative to “rights” a good place to start is at the level of life’s innate rights a pattern found in the constructal law (the latest discovered law in thermodynamics by Professor Adrian Bejan):

http://www.bookdaily.com/book/3341166/scientific-proof-of-our-unalienable-rights-a-road-to-utopia

Adrian Bejan is slated to receive an award at the Franklin Institute in Philadelphia on April 19:

https://www.fi.edu/franklin-institute-awards

Thank you, all! The scale I am looking for is akin to a well developed environmental concern and is aimed for members of the general public as respondents (not experts). However, it seems that there exists no such a scale thus far...