The influence of inattention on the neural correlates of scene segmentation

Numerous experiments show that people are unable to report about unattended information. It is also clear that there is extensive processing in the absence of attention. Here, we study, by using an 'inattentional blindness' paradigm while measuring BOLD responses or MEG to texture displays, to what level of scene segmentation visual information is processed when subjects are not capable of reporting that segregating textures were present. We presented non-segregating and occasionally segregating textures in two different conditions: 1. a condition where subjects were not informed about the presence of the segregating textures while at the same time engaged in a foveal task, resulting in prolonged inattentional blindness and 2. a condition with similar task demands, in which, however, the subjects perceived the segregating textures. BOLD responses from early visual areas (V1, V2, V3, V4) and MEG responses up to 240 ms showed a significant difference between segregating and not segregating textures in both conditions and did not differ from each other, indicating that scene segmentation processes proceed normally during inattention. A difference between the two conditions, and hence an influence of attention, was signaled in area V3a and more parietal MEG sensors around 400 ms.