4 ms·
Part of the trick is that the boys are split into two parts and progress from more inside to more outside along the wheel. Since the unit "a boy" is based on re
by DoreenMichele 5y ago
Part of the trick is that the boys are split into two parts and progress from more inside to more outside along the wheel. Since the unit "a boy" is based on real world experience where boys can be different sizes and especially since how much space a boy takes up in an image can vary depending on angle, we mentally accept that this mashup of different amounts of body parts adds up to "one boy" rather than thinking "No, that's just 85 percent of a boy and over there we have 105 percent of a boy!"
As someone else noted, we accept in one position that two partial boys each count as a whole boy and then in another position we accept that they each count as just part of a whole boy when paired differently.
(Edited in hopes of improving clarity.)
- jonahx 5y agoTo add to this, the boy at 3 o'clock, whose head is split in two equal pieces, is the key to the sleight of hand. Does his head stay or does it move? If it moves, the boy at 2 o'clock should count as 2 heads in position B. If it stays, then he should count as 2 heads in position B, since the head below him moves up. But because it's ambiguous, we count it as both moving and not moving.
- foobarian 5y agoYeah the size of the boy half goes from say 5% to 95% around the circle, on both sides. In the 12 boys configuration the halves are paired correctly to add up to 100% sized boys. But in the other, there are 12 boys smaller than 100%, and then at 8 o'clock two 95% pieces appear together so we round them up to two. Neat illusion.
- Someone 5y agoLooked at it differently, we go between two states: 1+12, 2+11, 3+10, ..., 10+3, 11+2, 12+1 (12 pairs, each adding up to 13) and 0+12, 1+11, 2+10, ..., 10+2, 11+1, 12+0 (13 pairs, each adding up to 12)