Reasearch by Humphrey et al (2020) has confirmed what many cat owners already suspected: narrowing your eyes is the best way to build a rapport with cats.
Their study found that “cats respond to a human giving a slow blink stimulus by producing eye narrowing movements of their own”.
“Firstly, cats deliver more eye narrowing movements when their owners slow blink at them than when the owner is present in the room but not delivering this stimulus.”
“Secondly, when an unfamiliar experimenter gives the slow blink stimulus compared to adopting a neutral face, cats respond with a higher frequency of eye narrowing movements themselves.”
Their study also found that cats were more likely to approach people after slow blinking as opposed to having a neutral face.
“From the current study, the slow blink sequence appears to be an indicator of positive emotion in cats.”
Cats are also known to initiate a sequence of slow blinking with humans. The slow blinking behaviour may well be innate behaviour but could also be a result of domestication.
“It could be argued that cats have developed slow blink behaviours because humans appear to perceive slow blinking as positive and cats may have previously been reinforced by their owners for responding to slow blink sequences.”
“It is also possible that slow-blinking in cats originated as a mechanism to interrupt an unbroken stare, which is potentially threatening in social interactions; this could then have been elaborated by a combination of selection and learning in the domestic environment.”
“Socio-cognitive abilities of cats are an under-studied area, and future research on cat behaviours, such as slow blinking, could enhance our understanding of interspecific communication and the ways in which domestication has shaped the social behaviour of an ancestrally solitary species.”