I'm aware there are a number of ways of defining if something is conscious or sentient. Such as the ability to experience qualia, or the ability to be aware you're experiencing qualia. Another theory I came across was to measure it on the ability to deal with counterfactuals, because (the theory goes), humans are the only animals to show the ability to deal with 'what-ifs' whereas other animals only deal with the facts as they are. I want to read further into this for an upcoming essay, but I've been unable to locate anything else on this idea. Please can someone direct me to papers/writers on the subject?