Did You See How Fast That Car Was Going? (It Depends on the Model)

I’m fascinated by the ways our mental models can influence how we interpret and behave in the world of traffic. A new study by Graham Davies, “Estimating the speed of vehicles: the influence of stereotypes,” in Psychology, Crime and the Law, looks at this is an interesting way.

As described by BPS, Davies “played ten-second video clips of a BMW and a (smaller, less powerful) Volkswagen Polo to 42 undergrads and asked them to estimate how fast the cars were going. Based on past research showing that participants expect BMWs to be driven faster than Volkswagen Polos, Davies thought that the students would overestimate the speed of the BMW. In fact, he found the opposite. Participants tended to overestimate the speed of the Polo, perhaps because it was a noisier car, and smaller vehicles are generally perceived as going faster than larger cars.”

There was a bias here, but it seemed to be a perceptual bias.

“A second experiment pulled out all the stops in an attempt to provoke participants to rely on their driver stereotypes. Participants were told that the BMW was driven by a young male, and the Polo by a 62-year-old; they were shown photos of the drivers; and they were asked to speculate about the drivers’ personalities. But even after all this, the participants’ judgments of the cars’ speeds were still accurate and there was no tendency to overestimate the speed of the BMW. This was true even though participants had earlier made the kind of assumptions about the two drivers that you might expect — for example, that the BMW driver was more aggressive and reckless.”

Interestingly, it wasn’t until the third experiment that any predicted stereotype that BMW drivers drive faster was activated. A day after they viewed the speed clips, subjects were asked unexpectedly to recall the speeds. “In this case, the BMW’s speed was estimated to be significantly faster (56 mph) than the Polo’s (50 mph), even though both cars were actually traveling at the same speed (60 mph).”

I was reminded of work I had somewhere about stereotypes and “priming” — in some cases invoking presumed stereotypes seemed to force subjects to work harder to reject them. But when asked “out of the blue,” with no stereotypical context in mind, and perhaps less time or reason to think about the answer, the subjects here seemed to lean on preconceived notions that BMWs are driven faster. Davies’ experiment was meant as yet another calling into question of the reliability of eyewitness testimony, but as in the first experiment, it also shows the variety of ways the world of traffic is not always as it seems.

This entry was posted on Thursday, June 25th, 2009 at 6:33 pm and is filed under Traffic Psychology. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

Comments are closed.

Traffic Tom Vanderbilt

How We Drive is the companion blog to Tom Vanderbilt’s New York Times bestselling book, Traffic: Why We Drive the Way We Do (and What It Says About Us), published by Alfred A. Knopf in the U.S. and Canada, Penguin in the U.K, and in languages other than English by a number of other fine publishers worldwide.

Please send tips, news, research papers, links, photos (bad road signs, outrageous bumper stickers, spectacularly awful acts of driving or parking or anything traffic-related), or ideas for my Transport column to me at:

For publicity inquiries, please contact Kate Runde at Vintage:

For editorial inquiries, please contact Zoe Pagnamenta at The Zoe Pagnamenta Agency:

For speaking engagement inquiries, please contact
Kim Thornton at the Random House Speakers Bureau:

Order Traffic from:

Amazon | B&N | Borders
Random House | Powell’s

U.S. Paperback UK Paperback
Traffic UK
Drive-on-the-left types can order the book from

For UK publicity enquiries please contact Rosie Glaisher at Penguin.

Upcoming Talks

April 9, 2008.
California Office of Traffic Safety Summit
San Francisco, CA.

May 19, 2009
University of Minnesota Center for Transportation Studies
Bloomington, MN

June 23, 2009
Driving Assessment 2009
Big Sky, Montana

June 26, 2009
PRI World Congress
Rotterdam, The Netherlands

June 27, 2009
Day of Architecture
Utrecht, The Netherlands

July 13, 2009
Association of Transportation Safety Information Professionals (ATSIP)
Phoenix, AZ.

August 12-14
Texas Department of Transportation “Save a Life Summit”
San Antonio, Texas

September 2, 2009
Governors Highway Safety Association Annual Meeting
Savannah, Georgia

September 11, 2009
Oregon Transportation Summit
Portland, Oregon

October 8
Honda R&D Americas
Raymond, Ohio

October 10-11
INFORMS Roundtable
San Diego, CA

October 21, 2009
California State University-San Bernardino, Leonard Transportation Center
San Bernardino, CA

November 5
Southern New England Planning Association Planning Conference
Uncasville, Connecticut

January 6
Texas Transportation Forum
Austin, TX

January 19
Yale University
(with Donald Shoup; details to come)

Monday, February 22
Yale University School of Architecture
Eero Saarinen Lecture

Friday, March 19
University of Delaware
Delaware Center for Transportation

April 5-7
University of Utah
Salt Lake City
McMurrin Lectureship

April 19
International Bridge, Tunnel and Turnpike Association (Organization Management Workshop)
Austin, Texas

Monday, April 26
Edmonton Traffic Safety Conference
Edmonton, Canada

Monday, June 7
Canadian Association of Road Safety Professionals
Niagara Falls, Ontario

Wednesday, July 6
Fondo de Prevención Vial
Bogotá, Colombia

Tuesday, August 31
Royal Automobile Club
Perth, Australia

Wednesday, September 1
Australasian Road Safety Conference
Canberra, Australia

Wednesday, September 22

Wisconsin Department of Transportation’s
Traffic Incident Management Enhancement Program
Statewide Conference
Wisconsin Dells, WI

Wednesday, October 20
Rutgers University
Center for Advanced Infrastructure and Transportation
Piscataway, NJ

Tuesday, March 8, 2011
Ontario Injury Prevention Resource Centre
Injury Prevention Forum

Monday, May 2
Idaho Public Driver Education Conference
Boise, Idaho

Tuesday, June 2, 2011
California Association of Cities
Costa Mesa, California

Sunday, August 21, 2011
American Association of Motor Vehicle Administrators
Milwaukee, Wisconsin

Wednesday, October 26, 2011
Attitudes: Iniciativa Social de Audi
Madrid, Spain

April 16, 2012
Institute for Sensible Transport Seminar
Gardens Theatre, QUT
Brisbane, Australia

April 17, 2012
Institute for Sensible Transport Seminar
Centennial Plaza, Sydney
Sydney, Australia

April 19, 2012
Institute for Sensible Transport Seminar
Melbourne Town Hall
Melbourne, Australia

January 30, 2013
University of Minnesota City Engineers Association Meeting
Minneapolis, MN

January 31, 2013
Metropolis and Mobile Life
School of Architecture, University of Toronto

February 22, 2013
ISL Engineering
Edmonton, Canada

March 1, 2013
Australian Road Summit
Melbourne, Australia

May 8, 2013
New York State Association of
Transportation Engineers
Rochester, NY

August 18, 2013 “Ingenuity” Conference
San Francisco, CA

September 26, 2013
TransComm 2013
(Meeting of American Association
of State Highway and Transportation
Officials’ Subcommittee on Transportation
Grand Rapids MI



June 2009

No, you probably won be compensated one million dollars; however, with the right blend of negotiating skills and patience, your efforts will be substantially rewarded!I have seen up to forty thousand dollars added to starting compensation through diligent negotiations. It is a way to significantly raise your standard of living and sense of self, simply by