Sean Parker: Facebook was designed to exploit human "vulnerability"

Sean Parker, the founder of Napster and former president of Facebook, said the thought process behind building the social media giant was: "How do we consume as much of your time and conscious attention as possible?" Parker was interviewed by Axios' Mike Allen Wednesday:

"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 a social validation feedback loop ... You're exploiting a vulnerability in human psychology ... [The inventors] understood this, consciously, and we did it anyway."

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House committees leading the impeachment inquiry against President Trump subpoenaed acting White House chief of staff Mick Mulvaney on Friday.

The big picture: This comes after nearly a month of White House refusals to comply with House investigations into whether Trump jeopardized national security by pressing Ukraine to interfere in the 2020 presidential election, and by withholding security assistance provided by Congress to help Ukraine, per the subpoena. The committees are demanding documents by Oct. 18.

• Stat du jour: 📉 U.S. economy adds 136,000 jobs in September, unemployment rate falls from 3.7% to 3.5%
• S&P 500: 2,952.01 (👆 41.38 — 1.42%)
• 1 2020 thing: 💰Elizabeth Warren's campaign raises $24.6 million in Q3, Steve Bullock raises $2.3 million
• 1 impeachment thing: 🏛️House Democrats subpoena the White House
• 1 tech thing: 🇮🇷 Microsoft says an Iranian group tried to hack a 2020 candidate
• 1 business thing: 🎨 Banksy painting sells for a record $12.2 million

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Sen. Ron Johnson (R.-Wis.) told the Wall Street Journal that he learned of a possible quid pro quo between the Trump administration and Ukraine's government from EU Ambassador Gordon Sondland.

The big picture: Johnson said that he pressed President Trump on the issue, which allegedly linked the distribution of $400 million in U.S. military aid with a Ukrainian investigation of former Vice President Joe Biden, in an Aug. 31 phone call. "He said ... 'No way. I would never do that. Who told you that?'" Johnson told the Journal of his conversation with the president.