Facebook Inc. COO Sheryl Sandberg and Twitter Inc. CEO Jack Dorsey headed to Washington, D.C., for a hearing in front of the Senate Intelligence Committee Wednesday on social media's role in combatting election interference.

The executives—two of the biggest names in tech—discussed changes their companies have made since the 2016 election and answered probing questions on bots, selling data and transparency in content moderation.

Notably absent was Google parent company Alphabet's CEO Larry Page, who was invited but didn't appear. The company had planned to send CLO Kent Walker but their offer was rejected, with the committee seeking a higher ranking official. Walker posted his testimony online anyway on Tuesday.

Committee members from both sides of the aisle had plenty to say to the tech bigwigs present, and some thoughts about what they'd like to see change. Here's what the Senate wants from tech, based on Wednesday's hearing:

1) A Top Google Exec At the Hearing

Google's decision to leave its seat empty irked a number of senators who made it a frequent topic of discussion. Both chairman Sen. Richard Burr and vice chairman Sen. Mark Warner said they were “disappointed” Google didn't show. Sen. Marco Rubio said the chair was left empty by the search company “maybe because they're arrogant.”

Sen. Thomas Cotton also had strong words for the Mountain View, California-based Google.

“Perhaps Google didn't send a senior executive today because they've recently taken actions such as terminating cooperation they had with the American military on programs like artificial intelligence, which are designed not just to protect our troops and help them fight and win our country's wars but to protect civilians as well,” Cotton said.

Cotton continued by contrasting Google's work with the U.S. government to the company's ongoing work with Chinese companies, which he described as “effectively arms of the Chinese Communist Party.”

“Perhaps they didn't send a witness to answer these questions because there is no answer to those questions, and the silence we would hear right now from the Google chair would be reminiscent of the silence that that witness would provide,” he said.

2) Bot Control

Senator Warner and Sen. John Reed brought up the prevalence of bots on platforms, and how companies should let users know they've interacted with one. The use of bots was prevalent in the spread of misinformation during the 2016 election.

“I'm not a technologist but it seems to me you could identify a bot's presence and notify your consumers that 35 percent or 80 percent of these messages have been generated electronically,” Reed said.

Dorsey said Twitter is working on identifying bots, and eventually labeling bots' accounts so human users know when they're interacting with one. He added it's difficult to identify bots that mimic humans online, and that his company is hesitant to start labeling some bots until they're able to label all of them.

“In consideration of labeling and context, we need to make sure that when people see that bot label, that they're assuming that everything it's not on is human. We need to make sure there's a precision and accuracy as we label those things,” Dorsey said.

Sandberg said Facebook has notified users who've liked fake accounts. The company has doubled its safety and security staff to more than 20,000.

3) And Transparency Around Data Collection, Sharing

There were also calls for increased transparency around the collection and sharing of user data on social media, with Warner calling on platforms to “let users know the value of their data” so they can make informed decisions. Facebook and Twitter both make money off of targeted advertisements on their platforms.

He also asked if users have a right to know what data is being collected and how it's being used. “I think that would go a long way to making this exchange better understood by individuals,” Warner said.

Sandberg said her company has released “privacy shortcuts” that allow users to download and view all of the information they have on Facebook.

Phillip Bantz contributed to reporting for this story.