Anchoring Bias

Anchoring and adjustment bias affects decisions because people make judgements and adjust based on their implicit reference points (anchors). For example, in the book by Judgement under Uncertainty, an experiment that asked people to guess the percentage of African nations that are members of the United Nations with two different prompts. The answers provided were anchored to the initial percentage phrase in the questions given by the experimenters. For example, if they were asked ‘was it more or less than 10percent?’ Participants gave significantly lower values of 25percent on average than when participants who had been asked ‘was it more or less than 65percent?’

Such a bias is also present in the judgement of disease risk by people. Researching in disease communication found that people insufficiently adjust their subjective risk, the anchor, to the objective risk value conveyed to them by a health care provider. This kind of risk perception is crucial in protection motivation theory which differentiates the cognitive process into two process, threat appraisal and coping appraisal. Inaccurate risk perception will lead patients to form low perceived vulnerability to a health threat and therefore not take precautionary measures against it. The consequence would be an increase vulnerability to the health threat.

The disease risk example can be generalised to environmental threats. In Singapore context, the prevalence of floods is low, hence the subjective risk that Singaporeans have towards flood is low. Hence there were no precautionary measures taken to ameliorate consequences of floods. However, in the recent years, there has been increasing number of flash floods in low lying areas like orchard road. Insufficient prevention led to shops being flooded and traffic to a standstill in affected areas.

From: pennysdaybook.com

It is therefore important to provide information of actual risk of a disaster because research has shown that with enough information, people can make more accurate risk perception and make more rational decision.