Google seems to be testing the ability to filter by perspectives. Google is testing a button to filter your query by the perspectives results.
This was spotted by Saad AK, he posted a video on Twitter, here is a GIF of that video in action:
Here is a still screenshot:
About a year ago, Google started to show perspectives and it officially went live a couple of months ago.
I find it interesting that this is being tested as a search filter...
Forum discussion at Twitter.
