"Humans feel safe in numbers," Ms Wilks says. "We seek confirmation of our decisions and comfort in all our choices." She says newspapers often spur the herd investment mentality.

Groupthink and herd investment encouraged money-center banks, pension fund managers and credit rating agencies in the United States, Japan and elsewhere to overlook the obvious signs of the corruption, mismanagement and chicanery among their borrowers.

Crash Hewat points out that shares, despite the crash, provided investors with average returns of 25 per cent in the second half of the 1980s.

He believes in a contrarian approach to share investment, in other words avoiding herd investments.