Two experiments were conducted to determine if infants attribute false beliefs to others when tested with the violation-of-expectancy procedure. In Experiment 1, the false-belief task was administered to 14- and 18-month-old infants. The procedure was identical to the one used by Onishi and Baillargeon (2005), except that two transparent boxes replaced the opaque boxes. Results revealed that infants looked longer when the agent searched in the empty box, a pattern of looking time opposite to the one typically observed with opaque boxes. It is, however, unclear whether infants' behavior was simply guided by their own visual access to the toy's location visible through the transparent box. To test this alternative explanation, Experiment 2 was conducted with 14- and 18-month-old infants. Infants were administered the same modified nonverbal false-belief task with transparent boxes, except that the agent wore a blindfold during the test phase. Contrary to Experiment 1, results revealed that infants were not surprised when the agent searched in either of the two transparent boxes and therefore appeared to treat her as ignorant. These findings demonstrate that infants' psychological reasoning system is more rigid than later forms when predicting an agent's future actions. (Contains 1 figure.)