The Trick Box

A box that isn’t what it says it is — and the delicious moment of being fooled. Show the child a familiar container (a raisin box, a crayon tin) and ask what’s inside. They’ll say the obvious thing. Open it: surprise — it’s something else entirely (a button, a pebble, a tiny toy). Then the two magic questions: “What did YOU think was inside, before we opened it?” and “Grandma hasn’t seen — what will SHE think is in here?” Realising that you yourself just held a wrong belief, and that others will too, is a powerful and slightly mind-bending step.

  1. Load the box in secret. Put the surprise inside, out of the child’s sight; close it up.
  2. Ask the prediction and have them commit. “What do you think is in a raisin box?” — “Raisins!” Say it out loud together.
  3. Open it — savour the mismatch. “SURPRISE! It’s a button!” Let the funny wrongness land.
  4. Ask the own-past-belief question. Close it again. “A minute ago, before we opened it — what did YOU think was inside?” (Target: raisins. This one is genuinely hard — children often say “button.”)
  5. Ask the other-person question. “Grandma’s coming over and she hasn’t peeked. What will SHE think is in here?” (Target: raisins.) Then actually test it on a willing family member for a thrilling confirmation.
  6. Say the principle out loud. “The box LOOKS like raisins, so anyone who hasn’t looked will think raisins — even though we know better!”

Variation: Trick Box of the Week — a new disguised container each week. Closed-Hand Guess — “what’s in my fist?” Wrapped “Present” that turns out to be something silly. Build-a-Trick — let the child load a box to fool someone else.

Requirements

  • Space: Anywhere
  • Surface: N/A
  • Materials: A container with a strong identity (raisin box, crayon tin, plaster tin) plus a surprising filler (a button, a sock, a pebble, a small toy)
  • Participants: 1 adult + 1 child; even better with a third person to test the prediction on
  • Supervision: Adult-led game

Rationale & Objective

The unexpected-contents task — Perner, Leekam & Wimmer’s (1987) “Smarties” study — is the other canonical false-belief test, and it carries a unique payload: it surfaces the child’s representation of their own just-past false belief. Around 70% of 3-year-olds, shown a sweet box that turns out to hold pencils, will say they “always” thought it held pencils and that a friend will think so too — failing to represent even a belief they held moments earlier. Gopnik & Astington (1988) showed this understanding of “representational change” emerges around 4–5 and is, if anything, slightly harder than reasoning about another person’s false belief, which makes the own-past-belief question the most interesting part of the game. Honest framing — pair this gleeful “trick” explicitly with honesty talk (we trick for fun and then we always tell the truth), keep the surprise good-natured, and don’t drop the harder own-past-belief question just because it’s harder; that reflection on one’s own changed mind is the whole point.

Progress Indicators

  • Early: answers “button” to both questions — current knowledge overwrites both memory and other people’s minds
  • Developing: gets the other-person question right but the own-past-belief one wrong (or vice versa), or needs prompting; the two can come apart
  • Proficient: confidently reports “I thought raisins, and Grandma will think raisins too”
  • Advanced: anticipates the joke (“she’s gonna say raisins!”), explains it (“because she didn’t look”), and starts building trick boxes to fool others while cheerfully admitting “I was tricked at first too”

Safety Notes

  • This is a deception game — pair it with honesty: distinguish a playful, consented, instantly-revealed “surprise” from real lying
  • If the child seems embarrassed at being fooled, normalise it: “everyone thinks raisins — that’s what makes it a great trick!”
  • Don’t use food the child is genuinely hungry for as the fake-out if that would upset them
  • Back off if frustration rises; the own-past-belief question is hard and meant to be playful, not a test

Hints

  • Playfulness: ham up the reveal; let the child set the next trap and fool you or another adult
  • Sustain interest: make it a weekly “trick box”; choose fillers surprising enough to get a real laugh
  • Common mistake: picking a filler too plausible (no surprise); revealing before the child commits to a prediction; skipping the own-past-belief question because it’s harder
  • Limited materials: a closed hand, a wrapped box, or any opaque container you already own
  • Cross-domain: metacognition and memory (reflecting on your own changed mind); language (thought, really, looks-like); emotion (surprise, being good-naturedly fooled); cognitive flexibility (holding two ideas at once)
  • Progression: predict and be surprised → answer the other-person question → answer the own-past-belief question → explain why anyone is fooled → build trick boxes for others

Sources

  • Perner, J., Leekam, S. R. & Wimmer, H. (1987). “Three-year-olds’ difficulty with false belief: The case for a conceptual deficit.” British Journal of Developmental Psychology, 5(2), 125–137
  • Gopnik, A. & Astington, J. W. (1988). “Children’s understanding of representational change and its relation to the understanding of false belief and the appearance-reality distinction.” Child Development, 59(1), 26–37
  • Wellman, H. M. & Liu, D. (2004). “Scaling of theory-of-mind tasks.” Child Development, 75(2), 523–541
  • Wellman, H. M., Cross, D. & Watson, J. (2001). “Meta-analysis of theory-of-mind development: The truth about false belief.” Child Development, 72(3), 655–684
  • CASEL — Self-Awareness (recognizing one’s own thoughts) and Social Awareness
  • UK EYFS — PSED Self-Regulation ELG and Managing Self ELG (know right from wrong — supports the honesty talk)
  • Head Start ELOF — Social & Emotional (recognizes states in self and others); Approaches to Learning (cognitive flexibility)