Infants' physical knowledge affects their change detection.

Prior research suggests that infants attend to a variable in an event category when they have identified it as relevant for predicting outcomes in the category, and that the age at which infants identify a variable depends largely on the age at which they are exposed to appropriate observations. Thus, depending on age of exposure, infants may identify the same variable at different ages in different event categories. A good case in point is the variable height, which is identified at about 3.5 months in occlusion events, but only at about 12 months in covering events and 14 months in tube events. In the present experiments, 11-month-olds detected a change to an object's height in an occlusion but not a covering event, and 12.5-month-olds detected a similar change in a covering but not a tube event. Thus, infants succeeded in detecting a change to an object's height in an event where height had been identified as a relevant variable, but failed to detect the exact same change in another event where height had not yet been identified as a relevant variable. These findings provide evidence that infants' physical knowledge affects which changes they detect in physical events. Possible mechanisms underlying these findings are also discussed, in light of recent accounts of change detection in adults.