Abstract
We investigated based on which spatial coordinate system, object-centered or ego-centered, the remembered area in boundary extension experiments was determined using both visual and motor tasks. On each trial, a partial image of a natural scene was presented for 3 sec (observation phase), followed by a mask of 1 sec. Participants were asked to choose the name of an object included in the image (recognition phase) and then to indicate the boundaries of the remembered area on the full-size image (test phase). In the visual task, participants adjusted the position of visually-presented lines so as to correspond to the boundaries of the remembered area. In the motor task, participants touched the screen to indicate the location of the boundaries. Between the observation and test phases, the center of the image was shifted according to different coordinate systems. In the ego-centered-shift condition, the image center was shifted leftward or rightward in ego-centered coordinates, but remained fixed in object-centered coordinates. In contrast, in the object-centered-shift condition, the image center was shifted leftward or rightward in object-centered coordinates, but remained fixed in ego-centered coordinates. In the control condition, the image center remained fixed in both coordinates. Results showed that the shift of image center affected the performances similarly in the visual and motor tasks, although the remembered area was generally narrower in the motor task. Moreover, in the object-centered-shift condition, the remembered area was narrower than that in the other conditions and shifted toward the image center of the full size image. In contrast, in the ego-centered-shift condition, the remembered area was nearly the same in location and size as that in the control condition. Stronger effects of the object-centered shift suggest that the boundary of the remembered image is determined according to object-centered coordinates in both visual and motor systems.
Meeting abstract presented at VSS 2016