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Stanford studies human impact when self-driving car returns control to driver
Researchers involved with the Stanford University Dynamic Design Lab have completed a study that examines how human drivers respond when an autonomous driving system returns control of a car to them. The Lab’s mission, according to its website, is to “study the design and control of motion, especially as it relates to cars and vehicle safety. Our research blends analytical approaches to vehicle dynamics and control together with experiments in a variety of test vehicles and a healthy appreciation for the talents and demands of human drivers.” The results of the study were published on December 6 in the first edition of the journal Science Robotics.
Holly Russell, lead author of study and former graduate student at the Dynamic Design Lab says, “Many people have been doing research on paying attention and situation awareness. That’s very important. But, in addition, there is this physical change and we need to acknowledge that people’s performance might not be at its peak if they haven’t actively been participating in the driving.”
The report emphasizes that the DDL’s autonomous driving program is its own proprietary system and is not intended to mimic any particular autonomous driving system currently available from any automobile manufacturer, such as Tesla’s Autopilot.
The study found that the period of time known as “the handoff” — when the computer returns control of a car to a human driver — can be an especially risky period, especially if the speed of the vehicle has changed since the last time the person had direct control of the car. The amount of steering input required to accurately control a vehicle varies according to speed. Greater input is needed at slower speeds while less movement of the wheel is required at higher speeds.
People learn over time how to steer accurately at all speeds based on experience. But when some time elapses during which the driver is not directly involved in steering the car, the researchers found that drivers require a brief period of adjustment before they can accurately steer the car again. The greater the speed change while the computer is in control, the more erratic the human drivers were in their steering inputs upon resuming control.
“Even knowing about the change, being able to make a plan and do some explicit motor planning for how to compensate, you still saw a very different steering behavior and compromised performance,” said Lene Harbott, co-author of the research and a research associate in the Revs Program at Stanford.
Handoff From Computer to Human
The testing was done on a closed course. The participants drove for 15 seconds on a course that included a straightaway and a lane change. Then they took their hands off the wheel and the car took over, bringing them back to the start. After familiarizing themselves with the course four times, the researchers altered the steering ratio of the cars at the beginning of the next lap. The changes were designed to mimic the different steering inputs required at different speeds. The drivers then went around the course 10 more times.
Even though they were notified of the changes to the steering ratio, the drivers’ steering maneuvers differed significantly from their paths previous to the modifications during those ten laps. At the end, the steering ratios were returned to the original settings and the drivers drove 6 more laps around the course. Again the researchers found the drivers needed a period of adjustment to accurately steer the cars.
The DDL experiment is very similar to a classic neuroscience experiment that assesses motor adaptation. In one version, participants use a hand control to move a cursor on a screen to specific points. The way the cursor moves in response to their control is adjusted during the experiment and they, in turn, change their movements to make the cursor go where they want it to go.
Just as in the driving test, people who take part in the experiment have to adjust to changes in how the controller moves the cursor. They also must adjust a second time if the original response relationship is restored. People can performed this experiment themselves by adjusting the speed of the cursor on their personal computers.
“Even though there are really substantial differences between these classic experiments and the car trials, you can see this basic phenomena of adaptation and then after-effect of adaptation,” says IIana Nisky, another co-author of the study and a senior lecturer at Ben-Gurion University in Israel “What we learn in the laboratory studies of adaptation in neuroscience actually extends to real life.”
In neuroscience this is explained as a difference between explicit and implicit learning, Nisky explains. Even when a person is aware of a change, their implicit motor control is unaware of what that change means and can only figure out how to react through experience.
Federal and state regulators are currently working on guidelines that will apply to Level 5 autonomous cars. What the Stanford research shows is that until full autonomy becomes a reality, the “hand off” moment will represent a period of special risk, not because of any failing on the part of computers but rather because of limitations inherent in the brains of human drivers.
The best way to protect ourselves from that period of risk is to eliminate the “hand off” period entirely by ceding total control of driving to computers as soon as possible.
Elon Musk
ARK’s SpaceX IPO Guide makes a compelling case on why $1.75T may not be the ceiling
ARK Invest breaks down six reasons SpaceX’s $1.75 trillion IPO valuation may be justified.
ARK Invest, which holds SpaceX as its largest Venture Fund position at 17% of net assets, has published a detailed investor guide to why a SpaceX IPO may be grounded in a $1.75 trillion target valuation.
The financial case starts with Starlink, SpaceX’s satellite internet constellation, which has surpassed 10 million active subscribers globally as of early 2026, with 2026 revenue projected to exceed $20 billion. ARK’s research puts the total satellite connectivity market opportunity at roughly $160 billion annually at scale, and Starlink is adding customers faster than any telecom network in history. That growth alone would justify a substantial valuation.
Additionally, ARK notes that SpaceX has reduced the cost per kilogram to orbit from roughly $15,600 in 2008 to under $1,000 today through reusable Falcon 9 hardware. A fully operational Starship targeting sub-$100 per kilogram would represent a significant cost decline and open markets that do not currently exist. SpaceX executed a staggering 165 missions in 2025 and now accounts for approximately 85% of all global orbital launches. That infrastructure position took decades to build and would be nearly impossible to replicate at comparable cost.
SpaceX officially acquires xAI, merging rockets with AI expertise
The February 2026 merger with xAI added a layer to the valuation that straightforward financial models struggle to capture. ARK argues that at sub-$100 launch costs, orbital data centers could deliver compute roughly 25% cheaper than ground-based alternatives, without power grid delays, permitting friction, or land constraints. Musk has stated a goal of deploying 100 gigawatts of AI computing capacity per year from orbit.
The $1.75 trillion figure itself is not a conventional earnings multiple. At roughly 95x trailing revenue, it prices in Starlink’s adoption curve, Starship’s cost trajectory, and the orbital compute thesis together. The public S-1 prospectus, due at least 15 days before the June roadshow, will give investors their first complete look at the financials to test those assumptions. ARK’s position is that the track record earns the benefit of the doubt. Fully reusable rockets were considered unrealistic for years. Starlink was considered financially unviable. Both happened on timelines that surprised skeptics.
Elon Musk
Ford CEO Farley says Tesla is not who to look at for EV expertise
Interestingly, Farley has been one of the most hellbent CEOs in terms of a legacy automaker standpoint to push the EV effort. It did not go according to plan, as Ford took a $19.5 billion charge and retreated from its EV push in late 2025.
Ford CEO Jim Farley said in a recent podcast interview that Tesla is not who Americans should look at to beat Chinese carmakers.
The comments have sparked quite a bit of outrage from Tesla fans on X, the social media platform owned by Elon Musk.
Farley said that Chinese automakers are better examples of how to beat competitors. He said (via the Rapid Response Podcast):
“If you’re an American and you want us to beat the Chinese in the car business, you’re all going to want to pay attention, not necessarily to Tesla. Nothing against Tesla—they’ve been doing great—but they really don’t have an updated vehicle. The best in the business for us, cost-wise and competition-wise, supply chain, manufacturing expertise, and the I.P. in the vehicle, was really BYD. In this next cycle of EV customers in the U.S., they want pickups and utilities and all these different body styles. But they want them at $30,000, not $50,000. Like the first inning, they want them affordably.”
Despite Farley’s synopsis, it is worth mentioning that Tesla had the best-selling passenger vehicle in the world last year, and in China in March, as the Model Y continued its global dominance over other vehicles.
Musk responded to Farley’s comments by stating:
“This is before Supervised FSD is approved in China. Limiting factor is production output in Shanghai.”
This is before supervised FSD is approved in China. Limiting factor is production output in Shanghai.
— Elon Musk (@elonmusk) April 19, 2026
Interestingly, Farley has been one of the most hellbent CEOs in terms of a legacy automaker standpoint to push the EV effort. It did not go according to plan, as Ford took a $19.5 billion charge and retreated from its EV push in late 2025.
Ford cancels all-electric F-150 Lightning, announces $19.5 billion in charges
Instead, Ford is “doubling down on its affordable” EVs and said it would pivot from its previous plans.
Reaction from Tesla fans was pretty much how you would expect. Many said they have lost a lot of respect for Farley after his comments; others believe he is the last CEO anyone should be taking advice on EVs from.
Nevertheless, Farley’s plans are bold and brash; many consider Tesla the most ideal company to replicate EV efforts from. It will be interesting to see if Ford can rebound from this big adjustment, and hopefully, Farley’s plans to replicate efforts from BYD work out the way he hopes.
Elon Musk
SpaceX wins its first MARS contract but it comes with a catch
NASA awarded SpaceX a $175 million Mars rover contract while the White House proposes cutting the mission.
NASA just signed a $175.7 million contract with SpaceX to launch a Mars rover that the White House is simultaneously trying to defund. The contract, awarded on April 16, 2026, tasks SpaceX’s Falcon Heavy with launching the European Space Agency’s (ESA) Rosalind Franklin rover from Kennedy Space Center in Florida, no earlier than late 2028. It would mark the first time SpaceX has ever sent a payload to Mars.
Under NASA’s Rosalind Franklin Support and Augmentation project, known as ROSA, the agency is providing braking engines for the rover’s descent stage, radioisotope heater units that use decaying plutonium to keep the rover warm on the Martian surface, additional electronics, and a mass spectrometer instrument, as noted by SpaceNews.
Those nuclear heating units are the reason an American rocket was required at all. U.S. export controls on radioisotope technology mean any payload carrying them must launch on a domestic vehicle, which narrowed the field to SpaceX and United Launch Alliance. Falcon Heavy’s pricing made it the practical choice.
SpaceX is quietly becoming the U.S. Military’s only reliable rocket
Falcon Heavy debuted in February 2018 and has 11 launches to its record. The rocket has not flown since October 2024, when it sent NASA’s Europa Clipper toward Jupiter. The three-core design, built from modified Falcon 9 first stages, gives it the lift capacity needed for deep space planetary missions that a single Falcon 9 cannot reach.
The Rosalind Franklin rover has been sitting in storage in Europe for years. It was originally due to launch in 2022 as a joint mission with Russia, but Russia’s invasion of Ukraine ended that partnership, leaving the rover built but stranded without a launch vehicle or landing hardware. NASA stepped back in through a 2024 agreement with ESA to rescue the mission. The rover is designed to drill up to two meters below the Martian surface in search of evidence of past life, a science objective no previous mission has attempted at that depth.
The contradiction at the center of this story is hard to ignore. The White House’s fiscal year 2027 budget proposal included no funding for ROSA and did not mention the mission at all in the detailed congressional justification document released April 3.
Musk has long argued that reaching Mars is not optional. “We don’t want to be one of those single planet species, we want to be a multi-planet species.” Whether this particular mission survives Washington’s budget fight, the Falcon Heavy contract means SpaceX is now formally on record as the rocket that could get humanity’s next Mars science mission off the ground.
The timing of this contract carries extra weight given that SpaceX filed confidentially with the SEC in early April and is targeting an IPO roadshow in the week of June 8. It would be the largest public offering in history.
ARK’s SpaceX IPO Guide makes a compelling case on why $1.75T may not be the ceiling
Ford CEO Farley says Tesla is not who to look at for EV expertise
