Research conducted at the University of Melbourne investigated whether detecting a change in a visual stimulus could occur in the absence of identification or localisation. The study, published 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.
In the study, observers were presented with pairs of colour photographs, both of the same female. In some cases, her appearance would be different in the two photographs. For example, the individual might have a different hairstyle.
Each photograph was presented for 1.5 seconds with a 1 second break between them. After the last photograph, the observer was asked whether a change had occurred and, if so, identify the change from a list of nine possible changes. Results showed study participants could generally detect when a change had occurred even when they could not identify exactly what had changed. For example, they might notice that the two photographs had different amounts of red or green but not be able to use this information to determine that the person had changed the colour of their hat.
This resulted in the observer “feeling” or “sensing” that a change had occurred without being able to visually identify the change. Thus, the result that observers can reliably feel or sense when a change has occurred without being able to visually identify the change could be explained without invoking an extrasensory mechanism.
The research was led by Senior Lecturer Dr. Piers Howe in collaboration with researcher Margaret Webb at the Melbourne School of Psychological Sciences, University of Melbourne.