Annals of Orb Research

Transcranial magnetic stimulation is like striking a
showroom dummy on the head with a clock-winding key.

Peer and Kendl have a theory that "reports on luminous perceptions during thunderstorms" -- i.e. ORBS ball lightning -- are caused by a rare form of lightning strike producing the right kind of magnetic pulse to directly stimulate an observer's visual cortex. An EMP attack on the brain, as it were. They compare this form of lightning to the transcranial magnetic stimulation that is used in a lot of current brain research and can produce 'phosphenes' if applied to visual cortex, and estimate that

roughly 1% of (otherwise unharmed) close lightning experiencers are likely to perceive transcranially induced above-threshold cortical stimuli.

There are various things wrong with this theory. In particular, to get phosphenes you need localised stimulation (which the clock-key butterfly-coil design can do well): "A huge phosphene area might then be more difficult to be detected".

Conversely, a nearby lightning strike is not so specific. It will stimulate motor cortex at the same time, so any ball-lightning-related visions will be accompanied by falling on the floor and twitching (see Fig. 2).

The other problem with TMS-induced phosphenes as an explanation for anything is that one needs to learn to see them -- for they are not like anything in the normal visual environment and do not fit into any familiar categories. People simply do not see them on first exposure, any more than they see Haidinger's Brush. Kammer et al. (2005) reported that 80% of their subjects learned to notice phosphenes in the first training session while "the remaining subjects have required up to four training sessions".

Once they've seen the fnords phosphenes, subjects can sketch their outlines, yet they have no edges -- for edge perception requires certain cells in V1 cortex to fire in the proper way, which a TMS pulse does not provide. Nor does it stimulate the neurons in V4 in the right way to give the phosphenes a coherent percept of colour -- they are sometimes described as 'achromatic', but that does not mean they are grey. They are a colour out of space.

Readers of Flann O'Brien know where I am heading:

In colour they were not white or black and certainly bore no intermediate colour; they were far from dark and anything but bright. But strange to say it was not their unprecedented hue that took most of my attention. [...] I can only say that these objects, not one of which resembled the other, were of no known dimensions. They were not square or rectangular or circular or simply irregularly shaped nor could it be said that their endless variety was due to dimensional dissimilarities. Simply their appearance, if even that word is not inadmissable, was not understood by the eye and was in any event indescribable.

Also, more evidence for the Nominal Determinism theory of science career choice:

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UPDATED: Bonus Painter of Orbs. (or possibly, of TMS phosphenes).
Richard Oelze.