In-Class Experiments #5 : Forer Fallacy of Personal Validation

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Forer Fallacy of Personal Validation : Inclass ExperimentMy strongest memory of all that I’ve studied during my MBA was an in-class experiment showing the fallacy of handwriting assessment. Now that I’ve turned a management/psychology instructor and am constantly seeking learning experiences that would stay with students for long, I attempted to run the classic Forer Fallacy of Personal Validation in class. Essentially, I wanted to show the students the bias we have in our need to self-validate.


[UPDATE September 2018: All teaching materials now shared on the teaching page]


To demonstrate the effect I told the class about my experiences in East-Asia regarding fortune telling and explained that companies spend millions to assess who candidates are based on more modern techniques like handwriting assessments. I gave the example that some companies ask candidates to write down their CVs in their handwriting even though they have a printed copies and explained that many companies use handwriting experts to learn about personalities and make recruiting decisions based on those analyses. I then told them of a handwriting expert company we use with the university and invited them to write down their names, their date of birth and copy the sentence “I want to know who I am”. Most students asked to participate in the assessment.

My teaching assistant helped me prepare personalized envelopes with the students’ names printed and carrying an official stamp of a made up company HIS which included the Forer personality statements on one side and a request for feedback on the other side (example). At the beginning of the follow-up class I ran a bonus quiz so that students will be seated separately from one another and then handed them the envelops asking students to remain quiet, go over the report carefully and then write down the feedback on the back.


Forer Fallacy : Fortune TellingThe effect was very strong. No one thought the report was bad (a zero on a scale of 0 to 5), only 4 thought the report was just average (score of 3) and 27 students thought the report was very accurate (rating of 4 or 5), reflected their personality and indicated that most statements were true about them. Regarding the question of whether they’d recommend to use this tool for personality assessment, only 2 students indicated that they would not recommend organizations to use it, with the rest endorsing this tool.

Needless to say that the students were surprised and disappointed when they learned that all students received the same statements, just as I did back in my MBAs. Responses ranged from anger to laughter. This inclass exercise therefore requires very careful debriefing and a detailed explanation of what the learning outcomes were. Though I can understand negative sentiments that may arise, I believe that more than anything this exercise provided students with a unique and personal learning experience they shall not soon forget, and this is what classes should be about – not Powerpoint presentations.

More on this with the materials can be found on my WIKI.

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8 years ago

Hey it’s JY. It’s been quite some time since I last visited this page. Looks much more beautiful than it was before. I like your sharing of in-class experiments series. 🙂