Prestimulus hemodynamic activity in dorsal attention network is negatively associated with decision confidence in visual perception

Attention is thought to improve most aspects of perception. However, we recently showed that, somewhat surprisingly, endogenous attention can also lead to low subjective perceptual ratings (Rahnev et al., 2011). Here we investigated the neural basis of this effect and tested whether spontaneous fluctuations of the attentional state can lead to low confidence in one's perceptual decision. We measured prestimulus functional magnetic resonance imaging activity in the dorsal attention network and used that activity as an index of the level of attention involved in a motion direction discrimination task. Extending our previous findings, we showed that low prestimulus activity in the dorsal attention network, which presumably reflected low level of attention, was associated with higher confidence ratings. These results were explained by a signal detection theoretic model in which lack of attention increases the trial-by-trial variability of the internal perceptual response. In line with the model, we also found that low prestimulus activity in the dorsal attention network was associated with higher trial-by-trial variability of poststimulus peak activity in the motion-sensitive region MT+. These findings support the notion that lack of attention may lead to liberal subjective perceptual biases, a phenomenon we call "inattentional inflation of subjective perception."