Abstract
Impossible figures, like the Penrose Rectangle, provide effective line junction information for the 3-dimensional shape of object parts. What makes a display “impossible” is that the parts cannot be combined into a consistent whole object. Previous work has shown that the ability to detect impossible figures improves between 7 and 14 years of age (Young & Deregowski, 1981). In contrast, in a recent study 4-month-old infants were habituated to a cube in which intersecting bars were occluded by an ellipse and then presented with two test displays in which the ellipse was removed. In one display the depth order of the bars was possible while the other showed an impossible version of the cube (Shuwairi, Albert & Johnson, 2007). The infants looked longer at the impossible cube. The study reported here used this method to investigate the developmental trajectory of the ability to understand impossible figures in toddlers. This study investigated 3- to 6- year-old preschool children's ability to detect the impossibility of a tribox (Penrose Rectangle). First, to ensure children were capable of discriminating the subtle differences between the possible and impossible figures, they were shown these figures with the common interior lines removed and asked to do a matching task. Those who passed the matching task were then asked to match a partially covered figure with either the possible or impossible figure. The result showed that children older than 4.5 years selected the possible figure reliably more often than the impossible figure. In contrast, the performance of the younger group was at chance.
These results suggest that 3- to 4.5-year-old children are poorer than older children at attending to conflicts between information provided by local spatial cues. Future work will be needed to reconcile these results with the report of sensitivity to impossible objects in infants.