Bias in the Spotlight: Inattentional Blindness 3

By Crawford Hollingworth and Liz Barker

Inattentional Blindness occurs when people focus on a task that demands their attention. This causes them to fail to notice a fully visible, but unexpected object or event which occurs in full view. People often don’t consciously perceive aspects in their surroundings that fall outside of their focus of attention. Tasks can be based around a static scene or a set of images – as Colgate shown shortly – or around a more dynamic scenario.

But why do people do this?

A well-known example of a dynamic scenario is the ‘Invisible gorilla’ experiment developed by Daniel Simons and Christopher Chabris in 1999. This is frequently used to illustrate inattentional blindness. If you’ve not seen it, don’t read any further, but watch and test yourself here!

Bias in the Spotlight: Inattentional Blindness

Most people are so focused on counting the number of basketball passes that they fail to notice the man in a gorilla suit waltzing onto the screen.

When asked in advance, most people feel confident of their ability to spot a gorilla in film footage of a basketball game or the presence of extra limbs in the photograph of a couple. The experiments demonstrate how little control we have of where our attention focuses and where it is blind.

An example of this can be seen by playing close attention to this 2-photo Colgate dental floss ad below:

Photo 1:

Bias in the Spotlight: Inattentional Blindness 1

Photo 2:

Bias in the Spotlight: Inattentional Blindness 2

Now you’ve looked, did you notice anything unusual?

Photo 1: did you see that the woman has too many fingers on her left hand?

Photo 2: did you spot the phantom arm resting on the man’s shoulder?

The Colgate campaign was designed to make us feel that when we have food stuck in our teeth it has such a powerful impact on others that they notice very little else about us, even a major physical defect like those in the images above. The copy on each ad reads:

“Not even that [insert anatomical oddity] gets more attention than a mouth without care.”

This ad sequence is a classic example of inattentional blindness. However, the ‘blindness’ effect may even go beyond our vision and affect other senses too, such as smell. One recent study by, Sophie Forster and Charles Spence, found that people were less likely to detect a strong smell of coffee in the room when given a cognitively demanding task to complete.

So what does all this mean?

Inattentional blindness has big implications:

  • Driving – most accidents occur due to human error. Many due to distracted driving. If we are too focused on something else whilst driving, perhaps we’re checking directions and thinking too hard about where we are going. This makes us less likely to notice a child stepping into the road, the cyclist turning right or the car ahead braking suddenly
  • Reliability of witness statements – memory alone is fallible but inattentional blindness shows that we might not notice a crime being committed if our attention is elsewhere. However, we could still be convinced that if such an act had occurred we could not have failed to notice it
  • Pick-pocketers – this crime heavily relies on inattentional blindness. Many distract someone by asking them a question or getting their attention whilst their bags and pockets are raided

Of course, the magician or con artist is dependent on people’s inattentional blindness. Their tricks rely on getting our attention focused on something else in order to blind us to their sleight of hand. Often, what lies behind the success of the magic or the con is simply our failure to pay attention…

In marketing, this concept is important for realising that in cluttered environments that direct our attention in lots of different ways, people might fail to notice what you want them to notice! Similarly, in research, it can be useful to find out what people have noticed in their environment and what they have missed.

Next in the series…

Every three weeks The Behavioural Architects will put another cognitive bias or behavioural economics concept under the spotlight. Our next article features Change blindness.

By Crawford Hollingworth and Liz Barker, The Behavioural Architects

Crawford Hollingworth is co-Founder of The Behavioural Architects – an award-winning global insight, research and consultancy business with behavioural science at its core, which he launched in 2011 with co-Founders Sian Davies and Sarah Davies.

Liz Barker is Global Head of BE Intelligence & Networks at The Behavioural Architects.



System 1 & 2


Optimisim Bias

Availability Bias