When the Crowd Makes Something Feel More Likely
Why do we think we’re more likely to win at the big casino versus the small one?
Imagine a lottery with 100 people, and every person has exactly the same chance of winning.
You have a blue ticket.
Now suppose 70 other people also have blue tickets, while only 30 have red tickets.
Does being in the larger blue group make your individual ticket more likely to win?
No.
Your odds haven’t changed at all.
Yet people may feel that they have a better chance simply because they belong to the larger category. This has been called Category Size Bias.
In one experiment, participants were willing to wager nearly 25% more when their lottery-ticket color matched a larger group—even though every individual ticket had the same objective probability of winning.
Why?
Our brains can accidentally transfer the probability of the group onto the individual:
“There are lots of winners likely to come from this category… therefore I must be more likely to win.”
You can see similar thinking in investing:
“Most successful companies are technology companies, and I own a technology company—so mine must have a good chance of succeeding.”
But belonging to a strong or large category doesn’t automatically make an individual member strong.
The lesson
Whenever you hear:
“Most successful X’s belong to this group…”
ask a second question:
“But what are the odds for this particular X?”
A large crowd can make something feel more probable without changing its actual probability.
Interestingly, later replication work challenged how robust the original Category Size Bias really is, suggesting that some of the observed effect may have resulted from how the experiments were designed.
That itself is a useful lesson:
Even cognitive biases can be vulnerable to cognitive bias.
