What trick-or-treating can teach us about human behaviour

This year, Halloween looked very different to previous years. The tradition in many countries of trick-or-treating was either scaled back or prohibited completely.

While trick-or-treating is a fun activity for children to dress-up and meet their neighbours, it is also a perfect opportunity to learn a few lessons in human behaviour.

Making two choices separately or at the same time

In the 1993 experiment, trick-or-treating children were divided into two groups (A or B) and offered a choice between two closely-related types of chocolate bars.

Children in Group A went to 1 house and were presented with a tray piled with ‘3 Musketeers’ and ‘Milky Way’ chocolates. The children were then told that they could pick any 2 chocolate bars as their treat.

In Group B, there were two houses involved. Children were presented with a tray at each house and offered only 1 chocolate bar each time.

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The children in Groups A and B were given the same total number of chocolate bars (2), but one group chose their 2 bars as one selection, while the other group chose each of their 2 bars one house at a time.

Do you think there was any difference in the chocolates chosen in Groups A and B?


In Group A, where the children chose their 2 chocolate at the same time, they always chose one of each. In Group B, where the children chose the chocolates one house at a time, only 48% chose to have one of each chocolate.

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What can we learn from this?

Further studies in other settings have shown similar results, where people have chosen more variety when they are selecting the items together vs separately.

We can learn from this experiment that by presenting options to users in two choices rather than one, we may influence a different selection. It goes without saying that the way we design our experiences should have our users’ best interests at heart.

Tricking children with different treat deals

For each child that knocked on his door, he would give them 3 Hershey’s Kisses (4 grams each).

He would then hold out his hands where he also had a smaller Snickers bar (20 grams) in one hand and a large Snickers bar (48 grams) in the other.

He then offered the children two options for trade.

  1. Trade 1 Hershey’s Kiss for the small Snickers
  2. Trade 2 Hershey’s Kisses for the large Snickers

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The children could clearly see the difference in the amount of chocolate and didn’t hesitate in giving up 2 of their Hershey’s Kisses for the large Snickers bar.

Kids in the second condition were offered different trades.

  1. Trade 1 Hershey’s Kiss for the large Snickers
  2. Take the small Snickers for free

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Which deal do you think these children in this condition chose?

The kids in the second group chose to take the free small Snickers bar rather than giving up 1 Hershey’s Kiss for the larger Snickers.

Ariely used this example with cute children in his book to describe how humans respond to the concept of ‘free’. He writes how offering something for free has a much stronger psychological pull than even offering something for just a few cents. With this example, he recommends businesses to give products away for free rather than a next-to-nothing price.

There’s something about free chocolate.

I must admit that on more than one occasion, I have filled my pockets with little complimentary chocolates from conferences I’ve attended. For some reason I chose to walk around with obviously bulky pockets and risk my public reputation for about $2 worth of chocolate.

Irrationality with a capital I (me).

  • Are you attracted to free things at conferences?
  • Have you ever taken from a hotel a $1 mini bottle of shampoo?

Senior Product Manager @ Campaign Monitor