YOU can tell a lot about a person from their eyes 鈥� including information about memories hidden from their conscious awareness, it seems.
By relating subtle eye movements to brain activity, Deborah Hannula and Charan Ranganath at the University of California, Davis, have shown that a brain structure called the hippocampus can be working with memories of previous experiences even when people have no conscious recollection of them.
The researchers showed volunteers images of faces paired with a variety of background scenes. They were later shown one of the scenes as a memory cue followed by three faces superimposed over that scene and asked to choose which face had originally been presented with it.
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During the memory cue and choice test, Hannula and Ranganath tracked what the volunteers were looking at while scanning their brains. Even when volunteers announced an incorrect choice, those whose hippocampus was more active when they were looking at the scene cue subsequently spent the most time looking at the correct face while trying 鈥� and failing 鈥� to consciously identify it (Neuron, ).
鈥淭his study has provided the clearest evidence to date that the hippocampus is very much engaged, even when one is incorrect,鈥� says , who studies the structure鈥檚 importance for memory in rats.