Researchers found that dogs blink more frequently when watching humans blink, especially their owners, suggesting blinking functions as a subtle social signal. While dogs did not directly synchronize individual blinks, increased blink rates in response to familiar people indicate that blinking may play a role in social attention, communication, and human–dog bonding.

https://royalsocietypublishing.org/rsos/article/13/8/rsos260512/483035/Blinking-together-the-modulation-of-eye-blinking