The study, published today in the journal PLOS ONE, found that people could reliably sense when a change had occurred, even when they could not see exactly what had changed.
For example, a person might notice a general change in someone's appearance but not be able to identify that the person had had a haircut.
Lead researcher Dr. Piers Howe from the Melbourne School of Psychological Sciences said the research is the first to show in a scientific study that people can reliably sense changes that they cannot visually identify.