Driving speed is altered by monocular Neutral Density filters : the Enright phenomenon

Carkeet, Andrew D., Wood, Joanne M., Robinson, Andrew, McCorriston, Jonathon, Pesic, Nina, & Warlow, Sarah (2012) Driving speed is altered by monocular Neutral Density filters : the Enright phenomenon. Optometry and Vision Science, 89(1).

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Introduction: An observer, looking sideways from a moving vehicle, while wearing a neutral density filter over one eye, can have a distorted perception of speed, known as the Enright phenomenon. The purpose of this study was to determine how the Enright phenomenon influences driving behaviour.

Methods: A geometric model of the Enright phenomenon was developed. Ten young, visually normal, participants (mean age = 25.4 years) were tested on a straight section of a closed driving circuit and instructed to look out of the right side of the vehicle and drive at either 40 Km/h or 60 Km/h under the following binocular viewing conditions: with a 0.9 ND filter over the left eye (leading eye); 0.9 ND filter over the right eye (trailing eye); 0.9 ND filters over both eyes, and with no filters over either eye. The order of filter conditions was randomised and the speed driven recorded for each condition.

Results: Speed judgments did not differ significantly between the two baseline conditions (no filters and both eyes filtered) for either speed tested. For the baseline conditions, when subjects were asked to drive at 60 Km/h they matched this speed well (61 ± 10.2 Km/h) but drove significantly faster than requested (51.6 ± 9.4 Km/h) when asked to drive at 40 Km/h. Subjects significantly exceeded baseline speeds by 8.7± 5.0 Km/h, when the trailing eye was filtered and travelled slower than baseline speeds by 3.7± 4.6 Km/h when the leading eye was filtered.

Conclusions: This is the first quantitative study demonstrating how the Enright effect can influence perceptions of driving speed, and demonstrates that monocular filtering of an eye can significantly impact driving speeds, albeit to a lesser extent than predicted by geometric models of the phenomenon.

Impact and interest:

2 citations in Scopus
1 citations in Web of Science®
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ID Code: 47279
Item Type: Journal Article
Refereed: Yes
Keywords: Driving, Speed perception, Enright Phenomenon, Pulfrich Phenomenon, Self motion
DOI: 10.1097/OPX.0b013e31823874bb
ISSN: 1040-5488
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Schools > School of Optometry & Vision Science
Copyright Owner: Copyright 2012 American Academy of Optometry
Deposited On: 29 Nov 2011 02:06
Last Modified: 15 Apr 2012 11:14

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