 It's important to understand how exactly cats communicate and, perhaps more importantly, how they don't communicate. Humans constantly vocalize their emotions, needs, and demands. Cats ignore humans because they were never bred or trained to listen and obey like dogs. Because cat behavior is based so much on natural survival instincts, they will not communicate if there is no need. Cat mothers in the wild will only use vocal communication with their kittens as a warning or alert to danger. If there is no imminent danger or need to communicate, well, a cat is literally not going to waste her breath. Therefore, if you are calling out to your cat but they don't need anything from you in that moment, they are not likely to respond.