The idea of driverless cars has created enough buzz to make it unlikely that people would collapse at the sight of one humming along beside them. But rather than guess at people’s response, some transportation experts have been trying to determine how people actually do respond.

And in the past day or two, a consequence of this effort has been to raise the question of whether a vehicle that has recently been rolling along the streets of Arlington, Va. is being guided by a driver disguised as a car seat.

What appaprently is under way in Arlington is a test of public reaction to the sight of a seemingly driverless car on the busy roads of the close-in suburb of Washington, D.C. The test is being conducted by the Virginia Tech Transportation Institute.

It appears that the experiment involves a car that appears to be without a driver, but in fact actually has one. The appeal of such a technique seems clear. Reactions could be gauged without risking the possible disruptions that could be caused by an actual automated car on a busy road.

A key to the test appears in a statement from the institute, indicating that a system has been devised to create the impression that a car is running without the aid of a human driver.

In the words of the statement, the “driver’s seating area is configured to make the driver less visible within the vehicle, while still allowing him or her the ability to safely monitor and respond to surroundings.”

The general aim is to help show how to design true automated vehicles; specifically the current study is , according to the institute, to look into the potential need for more signals on the outside of such vehicles.

But in the past few days a few sightings of the test vehicle led to discovery of another need: the need on the part of some to find out just what was going on.

In response to questions on Monday, a spokeswoman for the institute referred a reporter to the institute’s announcement about configuring the seating area. But the announcement gave no detail on how the desired degree of invisibility was to be obtained.

The lack of detail led to the appearance of this headline on a news account about the test.

“Is Virginia’s mysterious ‘driverless” van actually being driven by a man dressed as a car seat?”

The provocative headline, which appeared to capture the curious nature of the test, appeared on a news website titled THE WEEK. The site described itself as offering “all you need to know about everything that matters.”

THE WEEK cited in turn another news site, ARLnow, which said “a mysterious, seemingly driverless van” was spotted Thursday in the Courthouse and Clarendon neighborhoods.

It said nobody was in either the driver’s seat or the passenger seat.

In an update, posted Monday afternoon, ARLnow said that a reporter for WRC TV (Channel 4) had spotted the van Monday. It said that on further inspection, the reporter had indeed found a driver in the van. It said the driver was “disguised as a car seat.”

The characterization seems about as accurate and amusing as any. Video apparently obtained by the reporter appeared to show arms and legs protruding from behind what looked like the back of a standard automobile seat.

In its statement, the Virginia Tech Transportation Institute suggested that the arrangement does not place the driver in harm’s way.

It said that the development of the test vehicle “ focused on ensuring driver safety and included several months of piloting and testing the vehicle, first in controlled areas, then in low-density areas and finally in an urban area.”

So the disguise, if that is what it can be called, may represent one more painstaking step along the difficult path to bringing new technology to a society set in its ways and its traditions of travel.