Anantaporn Sena¹ (), Rosanne Rademaker², Chaipat Chunharas³; ¹Cognitive Clinical & Computational Neuroscience Lab, Chula Neuroscience Center, King Chulalongkorn Memorial Hospital, ²Rademaker Lab, Ernst Strüngmann Institute for Neuroscience, Max Planck Society, Frankfurt, Germany, ³Chulalongkorn University Chula Neuroscience Center, King Chulalongkorn Hospital

Orientation perception of simple stimuli, such as lines or gratings, is affected by cardinal biases. These biases cause exaggeration of orientations away from the perfect vertical or horizontal axes. Previous research suggested that these biases may be caused by our world's natural statistics which shape our perceptual system to be more sensitive to cardinal orientations. Our previous study had revealed similar biases when perceiving a 3-dimensional object (an upright sitting cat) rotating in certain axes. This finding supports the idea that people use cardinal axes as a reference to enhance perceptual sensitivity. The question that remains unclear was whether these biases were driven by the object-centric axis or the world-centric axis. To explore this, our current study investigated the effect of object orientation using a 3-dimensional rotation task with a different major-axis stimulus (a bus). Six participants were briefly presented with a stimulus in pseudo-randomized orientations along three axes: —roll, pitch, and yaw. They were then asked to reorient the probe stimulus to match the rotation degree of the sample. The results revealed error patterns similar to those observed in our previous study. Specifically, a repulsive effect at vertical and horizontal orientations was found on the roll axis. On the yaw axis, repulsive effects were observed on the front and back sides of the object, while attractive effects were seen on the sides. On the pitch axis, however, only subtle biases were found. These findings, consistent with our earlier research, suggest that the error response patterns in major axes are influenced by the world-centric axis rather than the object-centric axis in the perception of an object's orientation.