Abstract
Olson and Marshuetz (2005) argued that memory for ‘where’ influenced memory for ‘what’. In their experiments, participants performed a probe change detection task to detect whether a single face within a white box was same or different, irrelevant of its position. Response slowed down only when the face changed its position within the box on the probe display (Local-Change), but not when the face and the box maintained their relative position (Global-Change), or when the face and the box retained their initial locations (No-Change). Olson and Marshuetz interpreted these results that the information of relative location was incidentally conveyed into memory even when only non-spatial information was required to be encoded. The present study explored a more plausible explanation for Olson and Marshuetz's findings. In the original experiments, the number of trials corresponding to the No-Change and Global-Change condition was greater than the Local-Change condition. We assumed that this inequality among conditions might enable participants to expect the location of the face probe within the box. To exclude this possibility, we controlled the number of trials across the conditions with or without the relative position change. With this manipulation, response was delayed only in the Global-Change condition, contrary to the results of Olson and Marshuetz. Such discrepancy suggests that the benefit of keeping the relative position in object working memory task is due more to a top-down attentional shift, than an incidental encoding of relative location.
This research was supported by a grant (M103KV010021-05K2201-02110) from Brain Research Center of the 21st Century Frontier Research Program funded by the Ministry of Science and Technology of Republic of Korea.