Paranormal Investigations and Emotional Outbursts

We have completed quite a number of paranormal investigations to date.
The combined total of our experiences is quite something and touches apon many areas, such as the personality of the individuals that take part, individual and group reaction to the environment and unexplained occurences.
The most common and yet surprising aspect is that of the individual who experiences an emotional outburst during a vigil or seance.
One could argue that a paranormal investigation is the perfect platform for those of us who crave attention, but the people who have been involved in this phenomena are extremely quiet, personal individuals, who become most embarrised after the event.
On a number of occassions the person involved has been shocked to find that there are tears rolling down their face before they are aware that anything is strange.
They have confirmed that they feel no emotional upset at this time and cannot explain why they should be crying. The same personality sometimes experiences an emotional outburst. This comes from "out of the blue" and subsides just as quickly.
I am intrigued as to an explanation for this.
One theory may suggest that the individual is enjoying the limelight, although my previous statement concerning the personalities affected, makes this unlikely.
Another theory may suggest that they are "tuning" into an energy within the area of the vigil or seance.
Can anyone offer another theory or has anyone experienced this themselves.
I would be very interested to hear!