Neural correlates of visual search and change blindness: An fMRI study  

Kaplar M., Deak A., Toth L., Bognar P., Bernath L.
First author's affiliation: University of Pecs, Pecs, Hungary

The phenomenon "change blindness" means that people can not recognize changes between two or more stimuli, if there is a masking stimulus between the two others. This phenomenon gives us the opportunity to use change blindness in experiments examining attention. In a change blindness task the subjects have to recognize the difference between two similar pictures with a masking screen between them. This task can be used to map unconscious attention and the processing of unconscious information because the target (what? and where?) is unknown by the subject. In our experiment we examined if a conscious attentional task like visual search activates the same brain areas as solving a change blindness task. In an fMRI study we presented two very similar sets of stimuli, one for visual search, one for change blindness task. We used the activations during the a visual search task as baseline in the analysis of activations during the change blindness task. We got few activated brain areas like Middle Occipital and Temporal Gyrus, Fusiform Gyrus, Supramarginal Gyrus, Nucleus Caudatus and Thalamus due to performance. The activation of these areas can be explained well by the differences of a the two types (search vs. recognize, conscious vs. unconscious) of the two tasks used in the study.