Street Light Interference - AbsoluteAstronomy.com

Street light interference, or SLI, is an alleged anomalous phenomenon where a person seems to turn off (or sometimes on) street light

Street light

A street light, lamppost, street lamp, light standard, or lamp standard is a raised source of light on the edge of a road or walkway, which is turned on or lit at a certain time every night. Modern lamps may also have light-sensitive photocells to turn them on at dusk, off at dawn, or activate...

s, or outside building security lights

Security lighting

In the field of physical security, security lighting is often used as a preventative and corrective measure against intrusions or other criminal activity on a physical piece of property. Security lighting may be provided to aid in the detection of intruders, to deter intruders, or in some cases...

, when passing near them.

Although street lights can turn off by chance, such as high pressure sodium street lights cycling (turning on and off repeatedly) at the end of their life cycle, believers in street light interference tend to claim that it happens to them personally on a regular basis, more frequently than chance would explain. Some propose paranormal

Paranormal

Paranormal is a general term that designates experiences that lie outside "the range of normal experience or scientific explanation" or that indicates phenomena understood to be outside of science's current ability to explain or measure...

explanations for SLI, sometimes based on scientific terminology, such as the explanation that electrical impulses in their brain interfere with the workings of electric lights. Anecdotes about people's experiences of SLI have been reported by news sources.

SLI has never been demonstrated to occur in a scientific experiment, and those who claim to cause it have been found to be unable to reproduce the effect on demand; they give the explanation that the effect is not within their mental and physical control. Many times they do report, however, that it occurs with specific lamps and not just randomly shutting off street lights or electrical lamps in general.

Hilary Evans and the The SLI Effect

Hilary Evans

Hilary Agard Evans was a British pictorial archivist, author, and researcher into UFOs and other paranormal phenomena.Evans was born in Shrewsbury, United Kingdom. and educated at St George’s School at Harpenden. After National Service in Palestine he went up to King’s College, Cambridge, to read...

, an English author who writes about paranormal subjects, coined the word "SLIder" to refer to someone who causes this effect, in his book The SLI Effect. In this book on page 15 he explains that a wide variety of street lamp types show
In the preface of the book Evans says,
On page 16 he explains what seems most likely to be happening,

Skepticism of SLI

The skeptical explanation to claims of SLI is to consider it an example of confirmation bias

Confirmation bias

Confirmation bias is a tendency for people to favor information that confirms their preconceptions or hypotheses regardless of whether the information is true.David Perkins, a geneticist, coined the term "myside bias" referring to a preference for "my" side of an issue...

: people are much more likely to notice when a street light near them turns on or off than they are to notice a street light in a steady state. This is compounded by a failure mode of street lights, known as "cycling", in which street lights of the high pressure sodium type turn off and on more frequently at the end of their life cycle. Also, a bizarre personal causal inference, especially in the case of inferring a relationship from one or few instances, is known as magical thinking

Magical thinking

Magical thinking is causal reasoning that looks for correlation between acts or utterances and certain events. In religion, folk religion, and superstition, the correlation posited is between religious ritual, such as prayer, sacrifice, or the observance of a taboo, and an expected benefit or...

. A top high pressure sodium engineer at General Electric

General Electric

General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...

, quoted by Cecil Adams

Cecil Adams

Cecil Adams is a name, possibly a pseudonym, designating the American author of The Straight Dope, a popular question and answer column published in The Chicago Reader since 1973. Ed Zotti is Adams' current editor....

, summarizes that SLI is "a combination of coincidence and wishful thinking". Massimo Polidoro notes in Skeptical Inquirer
Skeptical Inquirer
The Skeptical Inquirer is a bimonthly American magazine published by the Committee for Skeptical Inquiry with the subtitle: The magazine for science and reason....

that "Paranormal phenomenon is the least likely possibility."

External links

Street Light Interference amateur videos
"SLIder" illustrating light going out
"SLIder" illustrating light coming on
"SLIders" and the Street Light Phenomenon
Everything2 article - Street Light Interference
Yahoo Answers about Street Light Interference
Paranormal Phenomena: More Illumination on SLI
Web Poll of 1000+ people on SLIders phenomenon
The Washington Post: SLIders & the Streetlight Phenomenon
"SLI" in the James Randi Educational Foundation's commentary archives
ASSAP - a paranormal organization's view on how SLI should be investigated
The SLI Effect by Hilary Evans, a free download book on Street Light Interference. ISBN 0-9521311-0-2
"Bad Karma, or Just Bad Lightbulbs? The Mystery of Blinking Street Lights". Washington Post (Nov 17, 2002)
Close Encounters of the Street Lamp Kind. Independent (Aug 31, 1995)

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Hilary Evans and the The SLI Effect

Skepticism of SLI

See also

External links