A guide to everyday psychology

Psychological Processes

Cognitive and perceptual biases, the ‘halo effect’ and perceptual set.

This house in Germany only has flat surfaces!

Commentators often praise objectivity and ‘critical thinking’. But we are not ‘designed’ to understand the world completely objectively. Deeply ingrained among our psychological processes is an inbuilt bias about how we understand the things we see and hear (etc).

Sometimes known as confirmation biases, the effect of our biases is that we – often –  understand the world as we want to understand it, or expect to understand it. In the image above, we cannot resist seeing shapes and curved surfaces – no matter how hard we try!

Why do we have these biases? Because our cognitive and perceptual biases direct us towards what is – usually – the correct answer. The chances are far greater that, if a house looks like it has balconies, it actually does have balconies! So that is what our mind/brain commands us to actually see.

A crucially important thing to understand about these perceptual processes and biases is that they influence everything we think.

Being right – most of the time

Cognitive and perceptual biases are inbuilt in humans and other animals, and they are universal. At first glance, inbuilt biases might seem like a burden, causing us to misunderstand the world… However, the purpose of these biases is to ensure that we perceive and interpret the world as it usually is – and not how it appears on one specific occasion.

Consider the famous example of Lettvin’s Frog… The frog has a ‘bug detector’ in its retina. This cell only ‘fires’ when a small, dark object crosses the visual field of a frog in a jerky manner. That object could be a distant bird or airplane. And yes, it could even be Superman. But it isn’t. It is – nearly always – a flying insect. So the frog just goes for it. Perceptual bias seems to even be inbuilt in our neural circuitry. Bias = instant response = dinner.

Biases of that sort arise because the perceptual system evolved to perceive what is most likely to be true. Cats and dogs chase toys because they ‘know’ that small moving objects are nearly always prey. Nothing in evolution has prepared them to deal with humans – and their laser pens.

But let’s consider some simple human examples.

People’s biases

When we see a circular dinner plate from an angle, it appears to be an oval shape. But we still perceive it as circular. People appear ant-sized when we view them from great distance – but we still perceive them as full size. The technical name for this is ‘visual constancy’. It is a kind of perceptual bias that ‘encourages’ us to perceive things as they usually are, not how they look. This bias is fantastically useful in everyday life. Plates do not shift from circular to oval and back again. People are not ant-sized.

The psychological processes that create perceptual biases also affect our social perceptions – and the way we relate to other people in the world. So here are two reasonably well known types of cognitive/confirmation biases.

 Only seeing that we like – The Halo Effect

The ‘halo effect’ describes our tendency to judge people and events positively in line with our pre-existing likes and dislikes. And there is an equally important opposite, the ‘devil effect’). For example, people who like Boris Johnson tend to judge his bumbling manner generously. Those who dislike him find it infuriatingly contrived or proof that he really is an idiot. So when different people see exactly the same video of ‘Boris bumbling’, their pre-existing opinions about Boris determine their judgements.  The importance of this type of bias for eye-witness testimony is immense.

Targets for our innate bias are shaped by culture

We perceive good intentions in people we like and perceive bad intentions in people we dislike. People who dislike foreigners are far more likely to attribute (and ‘detect’) bad intentions in migrants than people who don’t. The list is endless, of course. Nearly all our ‘halo’ targets are learned culturally… We might learn to like (or dislike) dogs, communists, Jews, Moslems, Americans, Asians, French waiters and a million other things. And when we judge their actions and attitudes, we do not do it objectively. We judge people’s actions through the prism of our pre-existing likes and dislikes.

It’s why celebrity endorsement is so important in marketing. If a person I like tells me that a product is good, I’m more likely to  believe that it’s good. That’s the ‘halo effect’.

It is impossible to exaggerate how important this psychological process is in understanding our social interactions and our prejudices. Indeed, it is so important that we cannot really understand our prejudices without understanding the halo and devil effects. Once you like/dislike someone, it is difficult for you to see any bad/good in them. Culture determines the exact form that the ‘halo effect’ will take in any one of us.

A consistent world

The ‘halo effect’ also overlaps with other important psychological processes, especially stereotyping and cognitive dissonance (see the related articles), to produce complex feelings and behaviour.

We actually want the people we like to do good things – so that we can live in a ‘consistent’ world. Similarly, we want things and people we don’t like to do wrong. It is why Brexit-voting ‘leavers’ experience a small thrill when the EU stumbles. It is why former ‘remainers’ get a small thrill when Brexit causes the calamities that they predicted it would. We all like a consistent world – and interpret events in such a way that it is consistent.

Bias as a good thing

In terms of individual survival, our biases are broadly a very good thing. As social animals, we are compelled to trust other people. And taken overall, the people we like (immediate family, our tribe for example) will do ‘good’ things.

Of course, our ‘halo/devil’ judgements will sometimes turn out to be wrong, especially our social judgements. That person we dislike so much that we will not meet him him might be telling the truth. Nice Aunt Ethel actually is stirring arsenic into the tea. Perceptual bias is clumsy and rigid, like many other inbuilt psychological processes. It gives us a dogmatic view of the world.

But it is usually correct. And it usually improves survival. The price we pay for the safety provided by our biases is to hold opinions that are prejudiced and discriminatory. But evolution is interested in survival, not being nice. And for that reason perceptual bias is “in our DNA”. How do we overcome that?

Well, we can’t change the DNA. Not yet, at least. And being prejudiced is very much out of favour within Western cultures. So the only social solution lies in increased knowledge and awareness. We can’t prevent ourselves from attributing bad thoughts and deeds to people we dislike. But we can at least be aware of the biases – and try to prevent them from influencing our behaviour.

Only seeing things we expect to see – Perceptual Set

Overlapping heavily with the halo effect is a cognitive bias called ‘perceptual set’. It occurs whenever we ask ourselves a question – but we already have expectations (or preferences) about what the answer will be.

We have a very strong tendency (or ‘set’) to analyse events in such a way that they will confirm our expectations and preferences. We expect people we like to be ‘good’. But there are other causes of perceptual bias apart from liking things. Throughout life we develop a vast range of beliefs that shape our future expectations about what is true. If I believe that 2 + 2 = 4 then I expect 2 + 3 to be 5.

Perceptual set exists – and creates prejudices – in every field of human endeavour from repairing a car to developing theories about the universe. And why is this? It is because we rarely ask questions without having some advance expectations about what the answers will be – based on our existing knowledge.

Science and perceptual set

Science is not as objective as scientists would like it to be. Experiments nearly always start off with clear hypotheses – these are working expectations about what the answer will be.

The result is that scientists are strongly disposed to ‘notice’ evidence that confirms their hypotheses (the things they already believe to be true) – rather than notice evidence that disproves those beliefs. It is for this reason that objective science is always an ambition – never a fact.

Most scientists are aware of this reality. And the scientific protocol is that we should always test our theories negatively – in other words, try to disprove them rather than prove them. But alas, the real world doesn’t work like that.  Almost nobody gets a PhD if they discover – no matter how brilliantly – that their theory was wrong. So, in the real world, scientists often dump data that doesn’t fit.

Science, and the scientific method, is as close as we can get to objectivity. But it’s far from perfect.

Religion and perceptual set

Religious scholars are another group of people for whom perceptual set is a challenge to objectivity.

They ‘notice’ events that seem to confirm their beliefs about God more than events that seem to contradict them… To this day, there are still religious people who see the AIDS crisis as proof of God’s negative judgement on homosexuality.

Medicine and perceptual set

Medical diagnoses are also susceptible to confirmation biases, and nowhere more so than in psychiatry.

With its loose diagnostic criteria, circular logic and lack of any external criteria to cross-check a diagnosis, it is especially vulnerable to perceptual set. Today, there are whole communities of people posting on social media who believe that they have mental disorders and ‘brain issues’. It is so easy to ‘see’ the symptoms of a disorder, once we become convinced that it is present.

Rooting psychiatry in this kind of self-confirming perceptual set will eventually, in my view, turn out to be gravely damaging for generations of quite ‘normal’ young people.

The practical problem for everyday life

In societies increasingly characterised by all kinds of information overload, the outcomes of perceptual set are often harmful. And sometimes perceptual set can be catastrophic.  

Countless aircraft crashes have resulted from the tunnel-vision caused by perceptual set… Once people allow their expectations to determine their truth, it becomes very difficult for them to analyse information objectively – and interpret accurately what is in front of them.

 So why do people have all these confirmation biases?

Evolution has not favoured confirmation biases just to make fools of us and cause air crashes. Most of the time, our confirmation biases are based on years of experience – and most of the time they are correct, saving us lots of time.

When I see dark clouds, my bias towards concluding that this means rain is nearly always confirmed to be right. Perceptual set enables us to live in a world that is mostly consistent and predictable – and logical in its causes and outcomes. It is relatively stress free. We perceive what we expect to perceive – and this bias is usually correct. And, because we waste no time on analysis, it gives us those correct answers quickly enough that we can make use of them.

Living with the result of bias

We can’t just wish confirmation biases away. They are inbuilt. But we can be more aware of them… We become emotionally committed to particular conclusions because, for all kinds of reasons, we want them to be true or expect them to be true.

It is worth re-emphasising, finally, that perceptual bias is not an occasional phenomenon – and certainly not something that happens to other people while we are exempt. It shapes all our interpretations of pretty much everything we encounter. As always, to understand other people’s biases, we must first understand our own.

Confirmation biases create for us a world that is meaningful, predictable and internally consistent – and even happy. But it can be very resistant to change.

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