Working memory for stereoscopic depth is limited and imprecise—evidence from a change detection task

Abstract

Most studies on visual working memory (VWM) and spatial working memory (SWM) have employed visual stimuli presented at the fronto-parallel plane and few have involved depth perception. VWM is often considered as a memory buffer for temporarily holding and manipulating visual information that relates to visual features of an object, and SWM for holding and manipulating spatial information that concerns the spatial location of an object. Although previous research has investigated the effect of stereoscopic depth on VWM, the question of how depth positions are stored in working memory has not been systematically investigated, leaving gaps in the existing literature on working memory. Here, we explore working memory for depth by using a change detection task. The memory items were presented at various stereoscopic depth planes perpendicular to the line of sight, with one item per depth plane. Participants were asked to make judgments on whether the depth position of the target (one of the memory items) had changed. The results showed a conservative response bias that observers tended to make 'no change' responses when detecting changes in depth. In addition, we found that similar to VWM, the change detection accuracy degraded with the number of memory items presented, but the accuracy was much lower than that reported for VWM, suggesting that the storage for depth information is severely limited and less precise than that for visual information. The detection sensitivity was higher for the nearest and farthest depths and was better when the probe was presented along with the other items originally in the memory array, indicating that how well the to-be-stored depth can be stored in working memory depends on its relation with the other depth positions.

Impact of Information Placement and User Representations in VR on Performance and Embodiment

“…Our findings support the notion that when faced with more than one task in VR, the processing of nearby virtual objects is prioritized and these are detected more quickly, compared to virtual objects located further away. Such evidence is in line with past studies showing that visual changes in an image are noticed more quickly when they occur in the foreground compared to the background [3], or that near-depth changes in a stereoscopic image are noticed faster than when occurring at far depth [2]. Moreover, these results are also in accordance with a study that found drivers to be faster at detecting light changes at nearer depths compared to far away depths while driving in a non-immersive 3D environment [1].…”

“…Using a flicker paradigm with monocular and binocular cues, where participants are requested to detect color changes in different images, Ogawa & Macaluso [3] found that detection of changes in foreground/near objects is faster and more accurate compared to background/far objects. In accordance with these results, Qian & Zhang [2] also found higher detection sensitivity for changes in near depths compared to far depths in a change detection task including stereoscopic vision. Moreover, in 2D and 3D driving simulations, it has been shown that drivers are faster in detecting light changes at nearer depths compared to far away depths [1].…”

“…perceived depth cues, influence the processing of visuospatial information [1], [2]. In visual search tasks, there is evidence that humans are faster at detecting targets located in the foreground compared to targets presented in the background, when provided with depth cues [3].…”

Overestimation and contraction biases of depth information stored in working memory depend on spatial configuration

“…Several studies have used non‐action‐based tasks to investigate working memory for depth (i.e., depth working memory, DWM; Qian, Li, Zhang, & Lei, 2020; Qian & Zhang, 2019; Reeves & Lei, 2017; Tanaka, Yamamoto, Sung‐En, & Watanabe, 2016). Reeves and Lei (2017) investigated working memory for numerals that associated with depths using a partial report paradigm.…”

“…They found that the memory performance first fell with increasing cue delay but then recovered gradually, and suggested that it might take time for the depth representations of the numerals to transfer into a visual memory with depth tags. Qian and Zhang (2019) showed that DWM is severely limited in capacity by using a change detection task, in which a set of memory items located in various depth planes was briefly presented and observers needed to judge whether the depth position of the subsequently appeared test item differed from that of the memory item. The mean capacity, Cowan’s K (Cowan, 2001), for depth representation estimated from their study was 1.44, which was much lower than the putative capacity of 3–4 items for coloured squares (e.g., Luck & Vogel, 1997).…”