The present study investigated the process of updating or replacing the contents in object files using behavioral (reaction time) and psychophysiological (mismatch negativity) measures. Two moving letters were presented, and participants responded the target letter's identity as quirkily as possible. In the coherent condition, the two letters moved downward in natural way, keeping their spatiotemporal coherence. 1n the incoherent conditions, the two letters were replaced by each other or by new and different letters. In these cases, the spatiotemporal coherence was violated and participants had to update the information about each moving letter. The results showed that the reaction times were longer in the incoherent conditions than in the coherent condition. Mismatch negativity, which reflected the presentation of unpredictable events, was observed in the incoherent conditions. We propose that mismatch negativity is one measure to assess the efficiency of interface devices in daily lives.

Key words: object file, mismatch negativity, expectation