Nigeria, Oct. 19 -- Last time, this column dressed the researcher for the street.

It described the Visual Assimilation Protocol, the wardrobe of the worn and unremarkable, and the deep immersion through which a scholar-journalist or researcher may, for a time, become less conspicuous inside a decoupled zone.

That idea deserves more than a cliffhanger.

A methodology that asks a researcher to live under a borrowed role creates three obligations that cannot be avoided: the role must be disciplined, the researcher must be able to leave, and the deception must be ethically justified.

The third is the hardest. I take them in that order. The Persona Is a Contract, Not a Costume A wardrobe is the easy part of a persona. The hard part is every...