I've heard this referred to as the `mannequin effect', so named because
it would appear to be useful to have a mannequin on a trolley that one
could simply get up, go fetch, and talk to about the problem (as opposed
to bothering a presumably busy human about it).
Update: Of course, the mention was right here on PerlMonks
(not Advogato as I'd previously thought). See
this node, by lemming.