Monkey numerical distractions

2 minute read

This study has been out for a few weeks, and I’ve been meaning to put up a short comment about it: “Representational format determines numerical competence in monkeys”, by Vanessa Schmitt and Julia Fischer Schmitt:Fischer:2011. The abstract:

A range of animal species possess an evolutionarily ancient system for representing number, which provides the foundation for simple arithmetical operations such as addition and numerical comparisons. Surprisingly, non-human primates tested in ecologically, highly valid quantity discrimination tasks using edible items often show a relatively low performance, suggesting that stimulus salience interferes with rational decision making. Here we show that quantity discrimination was indeed significantly enhanced when monkeys were tested with inedible items compared with food items (84 versus 69% correct). More importantly, when monkeys were tested with food, but rewarded with other food items, the accuracy was equally high (86%). The results indicate that the internal representation of the stimuli, not their physical quality, determined performance. Reward replacement apparently facilitated representation of the food items as signifiers for other foods, which in turn supported a higher acuity in decision making.

This seems so obvious in retrospect. An experimenter has to provide some kind of motivation or there will be no experiment. Providing food rewards in psychology tests on animals will conflate numerical cognition with food, rewards, and motivation. I’m surprised that a simple substitution of inedible items turned out to be so successful in relaxing this cognitive bias.

As I’m thinking about the “numbers as technology” theme, I keep returning to the idea that most interesting technologies are cobbled together from heterogeneous parts. Cognitive technology is no exception. In this experiment, we see the interference between the food/reward aspects of cognition and the representation of number. To have an effective practice of number as applied to food items, an individual would have to overcome this interference.

We might tinker with the system in different ways – for example, we could set up a new system of behavioral rewards or we could change neurotransmitter regulation to decrease food salience. What is the dividing line between technical and natural solutions? Imagine a pill that improves monkey math by inhibiting dopamine receptors. The same inhibition might emerge by mutations to dopamine receptors – a natural tweak that alters the threshold of technical interventions. A new reward system might seem purely technical – in the experiment, it worked to substitute different kinds of food treats in different contexts. But then, “different” is itself a function of perception, which can be changed by changing visual and olfactory receptors. “Technical” is a matter of arranging heterogeneous things in such a way that their natural course of action achieves a desired end.