The first study showed infants a toy car that moved down an inclined track, disappeared behind a screen, and then reemerged at the other end, still on the track. The researchers created a "possible event" where a toy mouse was placed behind the tracks but was hidden by the screen as the car rolled by. Then, researchers created an "impossible event". In this situation, the toy mouse was placed on the tracks but was secretly removed after the screen was lowered so that the car seemed to go through the mouse. This indicated that they may have been surprised by the impossible event, which suggested they remembered not only that the toy mouse still existed (object permanence) but also its location. Also in the 1991 study the researchers used an experiment involving two differently sized carrots (one tall and one short) in order to test the infants response when the carrots would be moved behind a short wall. The wall was specifically designed to make the short carrot disappear, as well as tested the infants for habituation patterns on the disappearance of the tall carrot behind the wall (impossible event). Infants as young as months displayed greater stimulation toward the impossible event and much more habituation at the possible event. The same was true of the tall carrot in the second experiment. This research suggests that infants understand more about objects earlier than Piaget proposed.