Abstract
Perceptual judgments about stimulus features are biased towards stimuli presented in preceding trials. This bias, referred to as serial dependence, is thought to promote perceptual stability in a world where natural scenes are generally stable and continuous from one moment to the next. While serial dependence has been extensively investigated, to date it has only been studied using simple 2D stimuli (e.g. Gabor patches). Our current study moves the investigation of serial dependence into more natural settings by utilizing the more realistic environment offered by Virtual Reality (VR). Observers were presented with an object commonly encountered in daily life (e.g. a flashlight) and then required to report its orientation in an adjustment task within the VR environment. The distance between the observer and the object, and the plane in which the object was rotated, was manipulated. The object was rotated either in depth or in the fronto-parallel plane. In all conditions, observers’ orientation judgments were biased towards the orientation presented in the previous trials, showing standard serial dependence. Larger biases were observed when the object was further away in depth from the observer, and crucially the biases were larger when the object was rotated in depth compared to the fronto-parallel plane. Moreover, a larger bias was observed on the current trial when the object in the previous trial was closer to the observer. These results indicate that the additional uncertainty added by the 3rd dimension can yield larger and more robust positive serial dependence. We discuss this in the light that serial dependence is considered to be stronger with larger uncertainty about the visual input. Given that serial dependence is considered to be an adaptive strategy in naturalistic environments, we argue that examining it in VR provides more informative and potentially more accurate insights into perceptual history biases.