We notice, looking at all these people opening boxes, that when people get to about 13 out of 15 pies, their perception shifts, they start to get a bit bored, a bit testy.
Observamos al mirar a la gente que abre cajas que cuando van consiguiendo unas 13 de las 15 tortas cambia su percepción y empiezan a aburrirse un poco, a fastidiarse.