Searching for hidden objects in 3D environments

Erwan David1 (david@psych.uni-frankfurt.de), Melissa L.-H. Vo1; 1Scene Grammar Lab, Goethe University Frankfurt

The vast majority of visual search paradigms tend to use targets that are directly visible. However, in natural conditions, the target could be stored inside some furniture. Does knowing that a target may be hidden inside another object (e.g., drawer, box, oven) affect search behavior? To answer that question we created 28 virtual scenes modeled with interactable furniture, so that, for instance, one could open a refrigerator or a cupboard to look at its content inside. Participants wore a virtual reality (VR) headset to look for objects in 3 blocks of 27 trials (40s max.). In the first block, targets were always visible, while in block 2 and 3 targets could be hidden inside objects as well as visible. Participants did not know they could use the VR controller to interact with the scene until the start of block 2. We hypothesized that knowing that objects could be hidden, would alter participants’ search strategies, for instance, slowing down search due to the increased search space. However, compared to trials in block 1, our analyses show that participants were no less efficient searching for visible targets when there was a possibility that they could be hidden. In blocks 1 and 2, we report a decrease in average saccade amplitudes for visible and hidden targets, which we ascribe to the exploration of containers. As expected, searching for actually hidden targets increased scanning times and scanpath lengths, but had no effect on search initiation, target verification times or search success. In sum, knowledge about hidden objects did not significantly alter search behavior for visible objects in 3D environments. This study is the first in a series of hidden object paradigms in VR. Future experiments will explicitly investigate the importance of scene grammar related to object search efficiency.

Acknowledgements: This work was supported by SFB/TRR 26 135 project C7 to Melissa L.-H. Võ and the Hessisches Ministerium für Wissenschaft und Kunst (HMWK; project ‘The Adaptive Mind’).