Some 79% of people said they would not be able to fall asleep in a self-driving car—indicating a continued emotional discomfort with the technology, according to a new survey from The Zebra.

The findings show that due to safety concerns American consumers do not fully trust autonomous vehicle technology without supervision. 

More than half of those surveyed (54%) said they would continue to monitor the road while riding in a self-driving car. Others were a bit more confident and said they would use a one-hour ride to take their eyes off the road — with 13% saying they would utilize the time to use their cell phone. Another 11% would read a book and 10% would take a nap.

Additional activities that ranked for those willing to take their eyes off the road while cruising in an AV include watching a movie or television (5%), catching up on work (4%), and eating (3%).

The Zebra findings align with other recent research that indicates people are not quite ready to embrace self-driving technology. For example, AAA found that 71% of adults have fears about self-driving cars.

Moreover, although experts agree that human error accounts for anywhere from 75% to 94% of motor vehicle accidents, in a Pew Research survey 42% of respondents cited lack of control as their biggest concern about driverless vehicles. Another 30% cited safety as a top concern.

The Zebra used Google Consumer Surveys to survey 1,000 people in August.