Why shoppers prefer to buy yellow chickens

OFFER a group of 50 supermarket shoppers a shelf full of chickens identical in every way, except that one of them is yellow, and ask which they would choose. Even in the knowledge that the colour has no bearing on taste or nutritional value, most will choose the yellow one.

This classic test of decision-making was among the phenomena under examination in another project under the ESRC programme.

Michael Bacharach, professor of economics at Oxford University, Diego Gambetta, reader in sociology at Oxford, and Andrew Colman, reader in psychology at Leicester University, have recently completed their study, entitled Framing, Salience and Product Images.

It took as its starting point rational choice-based assumptions that underpin standard economic theory on purchasing decisions, which assume that price is overwhelmingly dominant.

"We are aware that there is a gap here. Rational choice does not provide all the answers," Professor Bacharach says.

The mix of disciplines in the project aims to add a layer of human reaction and behaviour to the work done by economic theorists. Drawing on previous work by psychologists such as the "yellow chicken" test and on their own laboratory experiments, the group have developed the "variable frame theory" of decision-making.

The key element is the "frame" - the set of concepts decision-makers use in describing the situation to themselves.

Some options are "salient", or conspicuous as the odd one out and hence likelier to provide a basis for making a decision. Hence the preference for yellow chickens and also the importance of "unique selling propositions" in marketing products.

The "frame" concept also helps to explain why people are likely to make cooperative, rather than individual, decisions in certain circumstances.

"If they are thinking of themselves as part of a group rather than simply as individuals, their decision-making will be framed in those terms," Professor Bacharach says.

* See research papers