I wonder, is that really meta-tool use? Doesn’t meta-tool use usually mean modifying a tool with another tool? Does picking a tool up count as modifying it?
Metatool use is defined as the use of one tool on another. In its most advanced form it does involve tool modification but there are simpler forms, such as gaining access to a useful tool.
Simply picking up a tool would not modify it. New Caledonian crows do spend time modifying stick tools. They strip bark off stick tools and removing side branches. Modification involves changing the natural form of an object.
Cognitively the difference between use and modification in metatool use is probably slim. The clever thing about both is that you have to get out of old habits. Normal tool use is directed towards food, just as most animal behaviour is directed to food (as long as you can’t have sex, in which case toss a coin). Redirecting tool use towards non-food objects that can potentially be useful has been seen in only humans, great apes and now, new Caledonian crows
I guess what I’m asking is whether you couldn’t explain the “meta-tool use” in the first experiment as something like chaining. It’d still be impressive, but cognitively, pretty different from meta-tool use. It would certainly mean that we wouldn’t have to have recourse to some sort of analogical reasoning to explain it. I don’t mean to imply that I think it has to be chaining, only that I’m not sure the experiments rule chaining and operant conditioning out as an explanation.
I’m not sure exactly what you mean by ‘chaining’. We felt we did rule out operant conditioning – the control of a second toolbox showed that the crows were not probing in an exploratory fashion – they didn’t probe because the toolboxes in themselves were interesting, they probed based on the contents of the toolbox. Thus learning based on trial and error seems very unlikely. I would be interested to hear how you think chaining and operant conditioning explain the performance of the crows.