A lot has been written and said about slow blink communication between cat and caregiver but it’s still ‘work in progress’, I’d suggest. The usual topic is that cats make the slow blink towards their human caregiver when they are content and relaxed. This is essentially one way traffic from cat to person, but can it be two-ways? And a study found that when an ‘experimenter’ made the softened face ‘smize’ followed by a slow blink the cats were more likely to (1) reciprocate and (2) approach the person. So there. According to science it works. However, in my opinion (and in the personal experience of many others), a domestic cat will provide a slow blink without the human doing the slow blink provided they substitute it with body language and actions which are equally friendly.
This is an interesting topic. My personal opinion is stated in the last section of the infographic. A slow human blink without more will not normally elicit one in response. The study contradicts that.
Here are some more articles on ‘strange’ cat behaviour. Strange cat behaviour is actually behaviour that some people don’t understand but it is not strange per se.