The new house effect
What's making noises in your house?
The picture above is an exaggerated (and inaccurate!) view of the voids in a typical house. These include an attic and the areas below floorboards and behind walls. All of these could conceal objects, particularly pipework, that is capable of producing odd sounds.
These sounds tend to be the same each day. Though we might not know exactly what they are, they become familiar, however dramatic some may sound.
Do you remember the last time you moved house (or flat)? Do you recall a moment when you woke up in the middle of the night in your new house, perhaps not quite sure where you were? Did you hear a distant knock or a loud creak nearby that caught you by surprise? Was there a shadow on the wall of your room that looked unfamiliar and even faintly sinister? This is the new house effect.
Until you get used to the peculiar sounds and sights (and even smells) of your new house, they can seem a little disturbing, particularly in the middle of the night when the relative quiet outside can appear to magnify them. If the creaks and knocks are particularly loud and frequent it might even sound as though there is 'someone else' in the house with you.
Many people report cases of haunting when they first move into a house, despite the previous occupants having had no problems. Similarly, it is often visitors to a building that first report strange things going on that the residents have never noticed. That's because the residents are used to all the creaks and groans that any building inevitably produces.
The most commonly reported odd occurrences in buildings are sounds. Many of the sounds originate in places you can't see; behind walls and under floorboards. This makes them difficult to explain. It is common for metal objects (such as pipes) to make knocking sounds as they contract while cooling down at the end of the day when there has been heating on. Floor boards can creak as people walk across them. Doors can even open by themselves if they are not secured properly. On windy days windows can rattle and tree branches might knock on walls or even doors. The wind in chimneys can often make spooky groaning noises.
It is less common to see things that puzzle newcomers to a building. That's because it's easier to investigate and explain what you can see. But there can be puzzling unfamiliar shadows and lights that can seem weird in the middle of the night. Lights from headlights in a road outside can send strange pools of light moving across walls and ceilings. Trees outside can cast spooky shadows with the help of street lights, sometimes animated by the wind.
When people go on a vigil they are looking for ghosts. Just telling someone a house is haunted will affect how they interpret anything they hear or see.
When people move to a new house they too may decide, for whatever reason, that the place has an 'atmosphere'. Once the idea is in place, lots of things will be interpreted in a paranormal context. Once established, it is a difficult idea to shift.
When faced with unfamiliar situations, some people react by feeling anxious ('fear of the unknown'). This can adversely affect how accurately they interpret their surroundings. This factor contributes to the New House Effect, increasing the likelihood of reports of unusual or paranormal phenomena, whether present or not. See also, the xenonormal - the unfamiliar but normal.
It's just the ghost!
When people first notice something odd going on in their homes, they are usually understandably reluctant to consider the possibility that it could be paranormal. However, once they have decided that it IS paranormal (for whatever reason), everything becomes paranormal! Not only are unexplained knocks down to the 'ghost' but so are apparently normal chance incidents. Anything that goes missing is now the 'ghost'. Any malfunction of a household appliance becomes suspicious. Unusual pet behaviour is attributed to supernatural causes.
Of course, not everyone reacts in this way but once the idea that a house is haunted takes hold, everything tends to be seen in a different light. Anything that doesn't have an immediately obvious cause can be attributed to the haunting.
All of these little incidents, that in other circumstances would be ignored as of no importance, now become evidence of paranormal activity.
When you go on a vigil at an allegedly haunted place for the first time, you will inevitably be subject to the 'new house effect'. Since you don't know what normal creaks, groans and shadows to expect, they can appear like paranormal phenomena.
The best way around this is to go repeatedly to the same vigil location. In addition to identifying (and eliminating) the natural sounds and sights of a particular location, you can also establish baselines for any instrumentation you are using.
If it is impossible to return to a particular location, all is not lost. You can always take along someone who is familiar with the building along. They should be able to tell you what is perfectly normal and what is, potentially, paranormal. You can also use positional baselines to try to get some meaningful instrumental data.
If you go on vigils several times to the same place (which you should), you may well notice that repeat visits never seem as 'active' as the first visit. You may also find that people who are new to the location report the most anomalous phenomena. This is, of course, the new house effect!