Blindsight and Echopraxia by Peter Watts

[Rynn]

Aside from Watt's setting where it can occur naturally (and he hints at a possible pathway in which the lower latency of non-conscious minds is an advantage) I don't see why it couldn't be designed. In OA the regular smart entities than run all the automation could just be collections of subsentient entities organised in a manner in which they assess and alter each other, with no global consciousness.