To What Extent do Investors in a Financial Market Anchor Their Judgments Excessively? Evidence From the Hong Kong Horserace Betting Market

A naturalistic study was employed to explore a new form of "basic anchoring." In particular, we examined the degree to which decision makers in a financial market, the horserace betting market. anchored their probability judgments excessively on a factor present in the environment at the time the judgments were made and which was relevant and informative to the judgment: the advantage afforded by a horse's barrier-position (BP). The results demonstrated that under certain conditions bettors anchored excessively on BP information revealed at previous race meetings, but not on the most recent race outcomes. In fact, bettors appeared to use the most recent race outcomes appropriately when forming probability estimates, but only when the results were in line with, what were likely to be, their expectations of BP advantage. Bettors with varying levels of expertise were shown to be subject to excessive anchoring, although greater expertise was generally associated with less excessive anchoring. The paper concludes that the manner and degree of basic anchoring in real-world environments is complex. Copyright (C) 2009 John Wiley & Sons, Ltd.