Self-driving cars are a type of technology that has the potential to enormously disrupt the world. They could affect transportation and shipping, change traffic patterns, make some jobs obsolete ... and open even more time for managing emails, memos, and phone calls.

All that ultimately depends on public acceptance of the technology. According to a new study from the University of Michigan Transportation Research Institute, more than half of people surveyed were welcoming to some degree of car automation. The question is what amount.

First, the caveats: The study included 505 respondents from a panel database offered by SurveyMonkey. The licensed drivers were fairly evenly split across age lines, skewed slightly female, and represented a range of incomes and geographic locations.

The single most frequent answer, offered by 43.8 percent of respondents, was a preference for no degree of self-driving in cars. In general that means that more than half of people are currently open to some degree of self-driving. Women, at 47.6 percent, were more strongly resistant to any degree of self-driving; 41.2 percent of men wanted a partial degree of self-driving. The interest in self-driving cars decreased with higher driver ages. Overall, 40.6 percent were interested in cars that had partial self-driving features; only 15.6 percent wanted completely self-driving cars.

It isn't clear how people construed the concept of "partial self-driving." It could be that they identified it with something like cruise control, which is common in vehicles.

More than 68 percent of people were moderately or very concerned about the idea of riding in completely self-driving vehicles, while only 10.6 percent had no concerns about self-driving vehicles. However, almost everyone -- from 94.4 percent to 98.1 percent, depending on age, wanted a steering wheel and gas and brake pedals to override any degree of self-driving.

Taken all together, the responses suggest that while there is a significant potential market for self-driving vehicles, there are a lot of concerns. Companies, whether manufacturers or providers of transportation services, will have to overcome fears and find ways to convince consumers that the technology is safe. At least they aren't flying cars, as people are dangerous enough in two dimensions.