Sean Parker shared strong words with Facebook founder, Mark Zuckerberg, on Wednesday.

Parker, 38, is the founding president of Facebook and founder and chair of the Parker Institute for Cancer Immunotherapy. At an Axios event at the National Constitution Center in Philadelphia he said that the largest social network on the planet is a behemoth that consumes people’s time, reported media outlets.

Parker was reportedly an early inspiration for Zuckerberg when Parker co-founded the music file-sharing site Napster in 1999 five years before Facebook. Parker was involved in the early days of Facebook, helping Zuckerberg raise institutional investment and maintain voting control of the company.

Referring to Facebook as “a social validation feedback loop”, Parker added, “That means that we needed to sort of give you a little dopamine hit every once in a while because someone liked or commented on a photo or a post or whatever… It’s exactly the kind of thing that a hacker like myself would come up with because you’re exploiting vulnerability in human psychology. The inventors, creators, it’s me, it’s Mark… understood this consciously and we did it anyway.”

“It’s a social validation feedback loop…. It’s exactly the kind of thing that a hacker like myself would come up with because you’re exploiting vulnerability in human psychology.” — Sean Parker

He said the thought process that went into building these applications — “Facebook being the first of them to really understand it” — was all about capturing your attention and never letting go. “That thought process was about how much do we consume as much of your time and conscious attention as possible,” Parker said. “That means we need to give you a dopamine hit every once in a while because someone liked or commented on a photo or a post, or whatever. And that’s going to get you to contribute more content.”

Zuckerberg, 33, has long maintained that Facebook brings people together. Now, the Facebook CEO says that connecting people online isn’t enough.

“We used to have a sense that if we could just do those things, then that would make a lot of the things in the world better by themselves,” Zuckerberg told CNN Tech. “But now we realize that we need to do more too. It’s important to give people a voice, to get a diversity of opinions out there, but on top of that, you also need to do this work of building common ground so that way we can all move forward together.”

Here’s some further reading on the evolution of social media and how it’s impacting society and our minds:

Check out what Jason Silva has to say about social media in the age of filter bubbles.