What Is SLI?
SLI stands for Street Light Interference — a reported phenomenon in which individuals appear to cause street lights to turn off, turn on, or flicker when they walk or drive near them. People who report experiencing this effect repeatedly are sometimes referred to as SLIders. While seemingly minor compared to other paranormal phenomena, SLI is notable for its high frequency of reports and the consistency of the described experience across a large number of independent witnesses.
What SLIders Report
Typical SLI reports describe street lights switching off as the person approaches and sometimes turning back on after they pass. Some SLIders report the effect extending to other electrical devices — causing watches to malfunction, computers to freeze, electronic doors to fail, and other electronic disturbances. The phenomenon is often reported as intermittent rather than constant, occurring more frequently during periods of emotional intensity, stress, or heightened psychological states. Many SLIders report having experienced the phenomenon for years or decades.
Research
The most extensive investigation of SLI was conducted by Hilary Evans, who collected and analyzed hundreds of SLI reports for the Association for the Scientific Study of Anomalous Phenomena (ASSAP). Evans documented consistent patterns across reports and proposed that the phenomenon, if genuine, might involve some form of unconscious psychokinetic interaction between the human bioelectrical field and electrical systems. However, no controlled experimental study has demonstrated the effect under laboratory conditions.
Conventional Explanations
Skeptics offer several explanations for SLI. Sodium vapor and mercury vapor street lights commonly cycle on and off as they age or overheat, and this normal cycling may coincidentally occur as someone happens to be walking nearby. Confirmation bias causes people to notice and remember the times a light turns off near them while ignoring the thousands of times it doesn’t. Observer expectation effects may also play a role — once a person begins paying attention to street lights, they are more likely to notice normal cycling behavior. The statistical probability of occasionally being near a light when it cycles is high for anyone who regularly walks or drives at night.
Related Terms
SLI connects to the broader study of PK (Psychokinesis), PSI (Parapsychological Phenomena), the research of ASSAP (Association for the Scientific Study of Anomalous Phenomena), and HSP (Highly Sensitive Person) research suggesting possible links between sensitivity and anomalous experiences.