Abstract
The visual processing of objects varies depending on where the objects are located in the visual field. For example, face detection and identification occur more readily when a face is presented in the upper visual field, rather than when presented in the lower visual field (Fecteau et al., 2000). This suggests that our visual attention is biased toward the face in the upper visual field. Recently, it was found that this upper visual field bias for faces has been acquired through development within one year (Tsurumi et al., 2022), however, the mechanism underlying the bias is unclear yet. The present study explored the stage at which the visual field bias occurs in the visual processing by introducing three object categories (face in Experiment 1, house in Experiment 2, 2D shape in Experiment 3). If the upper visual field bias occurs for not only faces but also simple objects such as 2D shapes, the visual field bias would reflect a characteristic originated from relatively lower visual areas like V1. Participants were presented with two objects from same object category presented concurrently on the top/bottom pair or right/left pair side by side for two seconds in each trial. The dependent measure was which object participants first looked at after the central fixation. Thus, we calculated the proportion of initial object fixation in each location. The results showed that the proportion of initial object fixation in the upper visual field was significantly higher than that in the lower visual field regardless of the categories of objects. There were no significant differences between the right and left visual field across all object categories. These results suggest that the upper visual field bias occurs at relatively lower level of visual system.