# The Effect of Retinal Eccentricity on Visually Induced Motion Sickness and Postural Control
## 1 Introduction
The researchers concluded that the central retina is dominant in object recognition and identification and the peripheral retina is dominant in visually induced self-motion and spatial orientation. The results of subsequent research, however, were mixed--and sometimes contradictory. Nevertheless, the majority of studies confirmed the findings of [PERSON] and colleagues (see [15] for an overview). Moreover, the intensity of section was shown to be enhanced with a wider field of view, thus reinforcing the peripheral efficacy for section [12, 16]. The widening of the field of view, in effect, expands the area of the retinal periphery that can be stimulated. The question can be raised, then, as to the effect of the increased stimulation in the retinal periphery on VIMS. Now that a variety of low-cost HMDs are available on the consumer market, this issue is particularly relevant. Equipped with high resolution and wide fields of view displays, these devices can convey a compelling sense of immersion in the virtual environment. The information depicted on an HMD describes the transformation of the entire scene, thus provoking an illusion of observer movement, that is, vection, which is assumed to be the prerequisite for VIMS [1, 2, 3, 17]. As the field of view provided by these devices becomes wider, the more effectively they convey section, along with a concurrent increase in the incidence of motion sickness [1, 15]. Indeed, VR engineers have manipulated the size of the visual field in an attempt to reduce motion sickness symptoms based on the general assumption that a wider field of view tends to aggravate sickness symptoms [18, 19, 20]. Research exploring the relationship between visual field and postural control has also demonstrated that the retinal periphery plays the dominant role in stabilizing posture, particularly in the anterior-posterior (AP) direction [12, 21, 22, 23, 24, 25, 26] (see [27] for review). In these studies, body sway was less with peripheral stimulation than with central stimulation [22, 23, 28]. Taken together, these findings suggest that the retinal periphery is more effective for inducing vection and for stabilizing posture. However, when considering VIMS, the findings are contradictory. VIMS is more likely to occur with section [1, 2, 3, 17] but less likely to occur with stable posture. The differing relationships of VIMS with vection and posture have been confirmed repeatedly. For example, extensive research by postural instability theory proponents at different laboratories hasdemonstrated convincingly that postural instability is the precursor to VIMS [10; 29; 30; 31; 32]. How can we reconcile these contradictory findings? One possible way to clarify the seemingly contradictory findings is to manipulate the complexity of visual motion used to produce vector. Most studies reporting stable posture under peripheral stimulation induced section simulating locomotion along a single axis, e.g., a collection of random dots that moved from left to right (i.e., linear vection [25; 26]), remained stationary [22; 23], or a drum that rotated about the vertical axis against a wall painted in black and white vertical stripes (circular vection, [12]) (see [27] for review). Although the intensity of the vection strength participants of these studies experienced is unclear, these visual motions may not adequately capture the dynamic nature of visual effects rendered in most VR applications. The present study investigated the effect of retinal eccentricity on VIMS and postural control in an immersive VR environment to determine whether the retinal periphery is still dominant even under more provocative visual stimulation. As noted earlier, VR engineers reduce the size of the field of view to ameliorate the symptoms of motion sickness [18; 19; 20].