Cognitive biases and educational research, an overview by John Hattie

John Hattie published an interesting post with an overview of possible cognitive biases translated to educational research. I do urge you to read the full post here, but wanted to share the biases here too:

Cognitive Bias Category Description
Authority Bias Tendency to attribute greater weight and accuracy to the opinions of an authority figure – irrespective of whether this is deserved – and to be influenced by it

EDUCATION: Don’t be swayed by famous titled gurus. Carefully unpick and test of all their assumptions – especially if they are making claims outside the specific area of expertise. Be particularly suspicious of anyone who writes and publishes a white paper [!!!]


Confirmation Bias


Post-Purchase Rationalization


Choice-Support Bias

The tendency to collect and interpret information in a way that conforms with rather than opposes our existing beliefs.


And when information is presented which contradicts current beliefs this can transition into Belief Perseverance i.e. where individuals hold beliefs that are utterly at odds with the data.


EDUCATION: We tend to select education approaches, products, and services that accord with our world view and will often continue to do so, even when convincing evidence is presented that our world view may be distorted. Be prepared to go against the grain and to question sacred assumptions.

 Observer Expectancy Effect


Observer Effect


Hawthorne Effect


Placebo Effect



The tendency for any intervention, even a sugar pill, to result in improved outcomes – mainly because everyone involved thinks the intervention will work and this creates a self-fulfilling prophecy


EDUCATION: If educational ‘sugar pills’ can generate positive effect sizes, then well-crafted education ‘medicines’ should generate a double whammy of effect plus placebo turbo boost – so opt for the latter.


 Ostrich effect The tendency to avoid monitoring information that might give psychological discomfort. Originally observed in contexts where financial investors refrained from monitoring their portfolios during downturns.


EDUCATION: The importance of collecting robust and regular data from a range of sources about the implementation of new interventions and analyzing this ruthlessly. Collect evidence to know thy impact.


 Anecdotal Fallacy


The tendency of taking anecdotal information at face value and giving it the same status as more rigorous data in making judgments about effectiveness


EDUCATION: Do not take spurious claims about impact at face value and do not invest in training based on participant satisfaction testimonials alone.



 Halo Effect Tendency to generalize from a limited number of experiences or interactions with an individual, company, or product to make a holistic judgment about every aspect of the individual or organization.


EDUCATION: Sometimes the whole is less than the sum of its parts. Just because an educational support organization has world-leading expertise in area A does not mean that they are also world leading in area B.


Not Invented Here Tendency of avoiding using a tried and tested product because it was invented elsewhere – typically claiming “but we are different here.”

EDUCATION: Be open to using and adapting existing expertise. Avoid reinventing the educational wheel – unless you work in terrain where wheels are useless [you probably don’t].


Ikea Effect  Tendency to have greater buy-in to a solution where the end-user is directly involved in building or localizing the product.

EDUCATION: Make the effort to localize and adapt tested solutions. This will generate greater emotional buy-in than standardized deployment.


Bandwagon Effect 

Illusory Truth Effect


Mere Exposure Effect

Tendency to believe that something works because a large number of other people believe it works.

EDUCATION: It might work and it might not. Test all claims carefully and don’t blindly join the bandwagon to keep up with the Joneses.


Clustering Illusion 

Cherry Picking

Tendency to remember and overemphasize streaks of positive or negative data that are clustered together in large parcels of random data i.e. seeing phantom patterns.

EDUCATION: Ask yourself: Are the claims made by educational researchers or service providers based on longitudinal data with a common long-term pattern, or from a small snapshot that could have been cherrypicked?


Conservativism The tendency to revise ones’ beliefs insufficiently when presented with information that contradicts our current beliefs.

EDUCATION: If the evidence is robust, it just might be true. There was a time when people who declared that the earth wasn’t flat were burned as heretics. But test all evidence as claims carefully.


Courtesy Bias The tendency to give an opinion that is more socially palatable than our true beliefs.

EDUCATION: Participant satisfaction scores from training events in some cultural contexts may be a grade or higher than the scores people would give if they were less polite.



Law of the Instrument If you have a hammer, everything looks like a nail.

EDUCATION: Start with the problem or ‘wicked issue’ you are trying to solve, and then work backwards to find the right instruments – rather than searching for nails to bang.


Bike-shedding The tendency to avoid complex projects like world peace to focus on projects that are simple and easy to grasp by the majority of participants – like building a bike shed.

EDUCATION: Don’t be afraid to go after the real problems. Build a bike shed if the world really needs bike sheds. If it doesn’t, then fix what needs fixing most.


Sunk Cost Fallacy 


Tendency to continue with a project that is not bearing fruit, simply because so much has been invested in it already and withdrawal would be an admission of failure.

EDUCATION: Review implementation of new approaches regularly and set clear kill parameters/hurdles that must be achieved for the project to stay live. Ruthlessly prune anything that does not pass the hurdle test.

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