However, this ability is limited by the location in which the new action is performed.

"Infants’ understanding of and exposure to familiar actions can boost their understanding of ambiguous action sequences. Their ability to draw on the past to interpret the present represents an important advance in their developing understanding of other people’s behaviour," said Jessica Sommerville, a UW assistant professor of psychology who is also affiliated with the university’s Institute for Learning and Brain Sciences.

For the study, the researchers conducted two experiments to test how well infants can use prior information.

In the first test, 48 infants received information about which of two objects a research assistant desired. Across five trials, infants consistently saw the assistant reach for, grasp and pick up one of two plastic toys (a green frog or a red fish).

For the second phase, the infants were randomly divided into same- and different-room conditions.

Half the babies stayed in the same room, but the setup was slightly different. This time the frog and fish each sat out of reach of the assistant on top of distinctly different colored cloths.

They watched as the researcher used the cloth supporting the toy that she had previous desired to retrieve the target toy. Infants’ visual attention to these events was measured, and after infants’ attention declined they participated in novel test trials.

The test trials varied. Some of them featured a change in the toy the assistant went after while others featured a change in the cloth that was used by the assistant.

Prior research suggests that 10-month-old infants do not spontaneously recognize the meaning behind the cloth-pulling sequence. They used infants’ visual attention to the novel test events to gauge infants’ understanding of the cloth-pulling sequence.

The researchers found that infants in the same-room condition showed heightened attention to a change in the toy that the assistant retrieved rather than a change in the cloth she used.

This, according to Sommerville, suggests that the infants understood that the assistant pulled the cloth in order to obtain her desired toy, and were surprised when her intention changed.

However, infants in the different-room condition did not distinguish between the two test events.

In the second experiment half of the infants were taken out of the testing room for 30 seconds after the first phase.

Then they returned to the same room. This time both groups of infants looked significantly longer at the change in the toy the assistant pulled with the cloth.