Decision Making. Do you have, Inattentional Blindness, Search Satisfaction and miss the Gorilla?

A Question: In a typical workplace situation, what percentage of information available do you scan (use) to make decisions?

Please use the scale below to indicate your answer:

img_6190Your Answer?

  • In the range 60-70% of available information?
  • Up to 75%? (I’m a logical and rational person)
  • MORE than 75%? (I deal in the evidence!)

The Reality? You probably use less than 10% of the available information to make a decision, particularly if you are making a quick decision.

It’s worth pausing and having a think about the implications of that statement.

There are some very good reasons for the low percentage, linked to how we have evolved to make decisions. Our decisions are typically “based on a partial data set, where we privilege our most recent experiences”and, “we use this partial information to make the quickest fit using established patterns, not the best fit”; both quotes are from Dave Snowden who explains further in the video below, (9.58mins to 12.27mins).

Superior Matches - Gorilla Brand
Superior Matches – Gorilla Brand
‘Only seeing what you are expecting to see’ 

Key to the explanation is a paper by: Drew, Vo & Wolfe in Pshycological Science, September 2013. (Psychol Sci. 2013 Sep: 24(9): 1848-1853, “The invisible gorilla strikes again: Sustained inattentional blindness in expert observers”.

The idea behind this experiment was to test if people fail to observe a very large and obvious ‘abnormality’ when they are focussed upon looking for something else. In other words, ‘will they only see what they are expecting to see?’.

In the example above the researchers had a library of scans of people’s lungs that contained cancer nodules (these are really hard to identify). They then placed an ‘abnormality’ in amongst the scans. The ‘abnormality’ was the picture of a gorilla, that was large and obvious. So large and obvious, it was approximately 48 times larger than a typical cancer nodule, the ‘size of a matchbox’ (Gorilla Brand Superior Matches).

Two groups of people were given the task of reviewing the scans to identify cancer nodules:

  • Group 1. Experts, highly experienced radiologists (skilled in this sort of work)
  • Group 2. Novices with 10 minutes training.

At the end of the exercise they were asked whether they had noticed anything abnormal, in other words, did you spot the gorilla? The results were as follows:

Adapted from: Drew, Vo & Wolfe. Pshycol Sci.2013 Sep:24(9) 1849-1853
Adapted from:
Drew, Vo & Wolfe. Pshycol Sci.2013 Sep:24(9) 1849-1853
Inattentional Blindness (IB) and Satisfaction of Search (SoS).

The paper is very clear that it is not meant to be any sort of criticism of the radiologists. They perform a highly skilled and challenging task. What the paper is highlighting is the phenomenon of Inattentional Blindness. Basically, if we aren’t expecting to see something, we don’t ‘see’ it, no matter how big and obvious.

The experiment went one step further on this and tracked the eye movements of the people looking at the scans. The results showed that for 12 out of the 20 radiologists who didn’t identify the gorilla, their eyes had actually ‘rested’ on the image. There are some fascinating pictures of the eye tracking scan in the paper.

The other idea the paper introduces is ‘Satisfaction of Search’. Basically this means that if you are looking for something, once you’ve found it, you tend to be less likely to find other anomalies. Your job is done. There is an interesting article from Liz O’Brien on MedPage Today, Beware the ‘Satisfaction of Search’, taking about this from the perspective of a proof reader.

A typical workplace situation. Going back to everyday decision making where this post started, the phenomena of Inattentional Blindness and Satisfaction of Search have far-reaching implications. Just to illustrate:

  • Problem Solving. You are faced with a routine problem, nothing major. When making the decision on ‘what next’, do you consider a wide range of possible options. Alternatively, do you have Inattentional Blindness to everything except the first reasonable option that comes to mind (often influenced by most recent experience)?
  • Reviewing Committee Papers. On a packed agenda there are three items with supporting paperwork that runs into about 10,000 words per item. How much of that information do you scan to make your decision? 5% or 75%?
  • Post Incident Investigation. You’ve reviewed documents and have spoken to people. Early on you ‘find’ a clear reason for what happened. From here onwards, how much does Inattentional Blindness affect your ability to see other reasons for the incident? Is ‘Satisfaction of Search’ having an impact?
  • Introducing an New Initiative. As one of the ‘troops on the ground’ you’ve  previously seen very many new initiatives from Senior Leaders. How much information from the ‘inspirational story’ about the ‘road map to excellence’ will you use in making your decision on how you will participate? 5% or 75%? (worth a look at the Dave Snowden video for more of this).

Are we doomed? Hopefully not. Previously I wrote about the Ladder of Inference and Confirmation Bias. Professor Chris Argyris who developed the idea of the Ladder of Inference speaks about ‘Climbing down the ladder’ as one of the ways of dealing with these biases. For me, this is the recognition that you are actually prone to biases, and need to do something about it. This can be a huge step for people who are ‘blessed’ with excessive self-belief. The other practical things you can do are:

  • Question your assumptions and conclusions – with someone who is prepared to challenge you,
  • Seek out contradictory data – am I only seeing what I expect to see?

Dave Snowden talks about having systems or rituals in place to force a different way of thinking. Having to rely upon our own individual cognitive abilities to do this is extremely difficult. More of that in the video and a follow up post.

Why the Gorilla? If you are wondering why a gorilla was used in the experiment, there is a long history of ‘invisible gorillas’ being used in observation and perception experiments. One of the most famous is the basketball test which you can see on Chris Chabris and Daniel Simons site about their book, The Invisible Gorilla.

So, What’s the PONT?

  1. In decision making, we don’t use as much of the available information as we think we do. It’s not a personal defect, just the way we have evolved to make decisions.
  2. Recognising that decisions are frequently made on partial information, to find the quickest solution, not the best solution, is a good staring point.
  3. Having systems and rituals in place to help people think about wider information and alternatives is more helpful than placing the burden upon the individual.

Here is the video of Dave Snowden (@snowded) at Public Services Wales Summer School in Lampeter, Summer 2016.

About WhatsthePONT

I'm from Old South Wales and I'm interested almost everything. Narrowing it down a bit: cooperatives, social enterprises, decent public services, complexity science, The Cynefin Framework, behavioural science and a sustainable future. In 2018/19 I completed a Winston Churchill Travelling Fellowship, looking at big cooperative enterprises and social businesses in NE Spain and the USA. You can find out more here:

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