The psychology of influence

In the video in the last Step, we explored the reasons for biased perception and the different systems of thinking we use to react to new information. Even using elaborative thinking (system 2) a reader may simply not have enough knowledge to interpret the results of a study correctly. But, let’s be honest, we often don’t pay a lot of attention or expend much effort on what we read, and here our brains sometimes trick us into drawing the wrong conclusion. We use heuristics to help us when processing a lot of information quite quickly and these can result in biased perceptions.

Psychology has identified many different forms of biases and heuristics.

• A bias is a consistent error in perception. For instance, people are often subject to the ‘optimistic bias’, that is they believe that they are less likely to experience negative events, and more likely to experience positive events, than their peers. In the food domain this means that people may find risks less relevant to themselves and engage less in self protecting behaviour.

• A heuristic is a simplified rule which we use to interpret information or make a choice. For instance, if you always look at the calorie content of a food, then this is an evaluation heuristic because, independent of all other information, you use this as a rule of thumb in judging the food product.

Some biases and heuristics have been shown to be commonly displayed in the population and they have implications when it comes to interpreting headlines that report nutrition science results.

a) Confirmation bias: This describes a tendency to seek evidence that confirms or verifies current beliefs. It also leads to discounting information that contradicts current beliefs. For instance, if a reader is of the opinion that cholesterol is bad for cardiovascular health, she is likely to discount studies that prove the opposite. Confirmation bias plays an important role in explaining why wrong beliefs about nutrition and health can be so persistent. It also explains why readers often get drawn into articles that confirm their beliefs. On social media it leads to ‘echo-chambers’, where people’s contacts and news feeds become more and more closely aligned with their beliefs.

b) Availability heuristic: This is a cognitive heuristic where our brains judge the probability or significance of an event based on the number of instances we have experienced or read about it and can readily bring to mind. The availability heuristic is especially interesting in the context of news headlines as the relative importance of an issue is judged by the relative ease with which it is retrieved from memory. And that is largely determined by how recently we’ve read something similar or how familiar we are with the topic – both controlled by the media itself. It’s easy to see how frequency of reporting can affect our perception of the significance of a topic.

c) Negativity bias: This bias describes our tendency to be more preoccupied with negative events than with positive events. This is because negative events have a stronger impact on our brain than positive ones. Imagine giving a presentation at work and receiving lots of positive feedback on it. There is also one negative remark on a tiny detail. We all have a tendency to focus far more on the negative remark than on all the positive ones. This is the negativity bias, mostly caused by the intensity of negative emotions. When reading headlines, negative news is often perceived as more credible and readers tend to pay more attention to negative headlines than positive ones.