More fishy thoughts

I ruminated about fishy pain in the other place on June 1st 2010, prompted by reading a book by a Victoria Braithwaite. Been moved to take another look at the book and have now spent some time ruminating about one of the other examples she gives.

Which is that if you give a healthy rat the choice between good water from one bottle and bad water - identical in appearance - from another, the rat will fairly quickly learn only to take water from the good bottle. However, the reason that the bad water is bad is that it has a bitter taste because of the pain killer which has been added to the water. So if we then do the same experiment with an old arthritic rat, that rat will fairly quickly learn only to take water from the bad bottle.

It is easy to give a human interpretation to this. The rat feels the pain in its joints. It associates the pain going with the bad bottle. It learns that the water from the bad bottle makes the pain go away. So it then opts for the bad bottle with the intention of getting the pain to go away. Or perhaps, more complicated, to get the pain to stay away. The rat is behaving in the same way as you or I would in similar circumstances. You or I would be making a conscious decision to put up with the unpleasant taste to get the longer term benefit. Take your medicine dear it's good for you sort of thing. So we infer that the rat is making a conscious decision in much the same way as you or I. That the rat is conscious in much the same way as you or I.

But while at first blush the experiment is very suggestive, we need to be careful. It would not be at all difficult to model the rats' behaviour with a computer; the program would not need to be very complicated and we would have no difficulty in judging the program to be unconscious, despite it copying, replicating or otherwise mimicking the rats' behaviour.

There is also confusion arising between the source of the pain and the signal of the pain. Doing something about the signal of the pain is not doing anything about the source and may not be very adaptive. But then, perhaps a rat brain is not up to worrying about the distinction. Learning to get rid of the signal of the pain is quite tricky enough as it is.

On the other hand, evolution is gradual and parsimonious. It does seem unlikely that we are the only animals to have consciousness and there seems to be general agreement that some mammals are conscious in the same way that we are, certainly conscious of pain and past causes of pain, but also capable of emotions. See, for example, Jeffrey Masson on cats (2002) (see also January 21st 2009 in the other place).

In this case, the rat body has clearly signalled pain to the rat brain, and I dare say the signalling is pretty much the same sort of thing that you would get in a human. The rat brain is clearly able to factor the circumstances of past pain and those of past absence of pain into its (usually correct) decision about which water bottle to use, a decision which needs memory, an ability to think about something other than the here and now. To send that decision down from the brain to the body and to get it done. Sophisticated stuff. But what does it all add up to? Is it the sort of action which I might manage unconsciously, somewhere in the lower regions of the brain, while pondering about when I might next be allowed to make lentil soup in the upper regions? Ambulatory ruminations clearly called for at this point.