Information and the Psychology of Investor Behaviour

In behavioural psychology the relationship between the information provided by a stimulus and an individual’s reaction thereto is widely accepted as parabolic and commonly referred to as a Wundt curve. The present paper invokes this relationship in order to examine the apparent failure of the efficient markets model as a paradigm for describing security price behaviour. Discrepancies between the prices and intrinsic values of securities are explained in terms of the amount of information entering the price determination process, with the amount required for an efficient market found to have an interior solution. The social invention of the stock market provides a convenient meeting ground in which to study the nexus between the psychology of investor behaviour and the economics of asset pricing.