Week 3: Memory outside the head

How the past constrains the present with no neurons involved, and the ninety-year mistake that arrived with it.

Part II — Interior models8 March 2027Open the slidesWeek 3 seminarSchedule

Physarum navigates by refusing to cross its own slime, which puts its memory on the substrate rather than inside it. Reid and colleagues (2012) established this by disguising the trail.

The bulk of the lecture is the Stentor case. Jennings described a behavioural hierarchy in one cell in 1906; the behaviourist era discarded it as irreproducible; Dexter and colleagues replicated it in 2019 and found the failed replications had used a different species with a different mode of life. A correct result was thrown away for most of a century because nobody checked a name.

I use this rather than a fraud case on purpose. Everyone involved behaved reasonably.