Item

Abstract

Nested radial objects (NEROs) were used to assess interactions between global and local motion during a representational-momentum task. NEROs consist of concentric rings of dots, with phase shifts between rings leading to structural variation. The NEROs were animated by making the rings locally rotate clockwise (CW) or counterclockwise (CCW) around their own centre. Global motion involved the rotation of the whole object around the centre of the screen, again either CW or CCW. When the object vanished, observers localised the remembered disappearance point, and then reported either the local or global motion direction, as cued at the start of each trial. Eye position (fixate/track), task (report local or global), and local - global congruence were the main factors of interest. Both angular error and deviations towards the screen centre were measured. Strong forward shifts in the remembered angle, regardless of eye position, with a congruent decrease only for fixated trials, were found. Fixation gave rise to a much larger bias towards the centre than tracked trials, but there was a clear increase in the size of this bias for congruent trials of both types. Reporting global or local motion did not influence responding in any way.