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

Abstract

Depth perception is essential for effective interaction with the environment. Although the accuracy of depth perception has been studied extensively, it is unclear how accurate the depth information is stored in working memory. In this study, we investigated the accuracy and systematic biases of depth representation by a delayed estimation task. The memory array consisted of items presented at various stereoscopic depth positions, and the participants were instructed to estimate the depth position of one target item after a retention interval. We examined the effect of spatial configuration by comparing the memory performance in the whole‐display condition where non‐target memory items were present during retrieval with that in the single‐display condition where non‐target memory items were absent. In the single‐display condition, we found an overestimation bias that the depth estimates were farther than the corresponding depth positions defined by disparity, and a contraction bias that the stored depth positions near the observer were overestimated and those far from the observer were underestimated. The magnitude of these biases increased with the number of to‐be‐stored items. However, in the whole‐display condition, the overestimation bias was corrected and the contraction bias did not increase with the number of to‐be‐stored items. Our findings suggested that the number of to‐be‐stored items could affect the accuracy of depth working memory, and its effect depended crucially on whether the information of spatial configuration of memory display was available at the retrieval stage.

Increasing perceptual separateness affects working memory for depth – re-allocation of attention from boundaries to the fixated center

“…However, several studies have demonstrated a systematic overestimation bias that memorized depth is likely to be recalled as farther (e.g. Campagnoli et al, 2017 ; Zhang et al, 2020 ). Zhang et al (2020) suggested that this might be partly due to a tendency toward a “default” position of dark vergence (the position where the eyes converge at in absence of visual input, about 1 m).…”

“… Campagnoli et al, 2017 ; Zhang et al, 2020 ). Zhang et al (2020) suggested that this might be partly due to a tendency toward a “default” position of dark vergence (the position where the eyes converge at in absence of visual input, about 1 m). Similarly, this default position, which is farther than the point of fixation in our study, may facilitate the performance in the depth plane with a positive disparity (farther).…”

“…It is suggested to serve as a link among sensory perception, long-term memory, and motor action, and therefore plays an important role in supporting other higher cognitive functions ( Baddeley, 2003 ; Baddeley, 2012 ). Although WM has long been a heated research topic in the field of cognitive psychology, most studies focused on WM that is responsible for holding visual or verbal information in a 2D context, and fewer investigated WM involving depth information ( Qian & Zhang, 2019 ; Qian, Li, Zhang, & Lei, 2020 ; Reeves & Lei, 2017 ; Zhang, Gao, & Qian, 2020 ).…”

“…The memory benefits of depth separation may arise from a process of reducing neural competition by utilizing cortically separable resources ( Chunharas et al, 2019 ), and thus facilitating the encoding of visual features ( Nakayama & Silverman, 1986 ). Conversely, it is possible that presenting items that each has distinct feature values (past research on WMd used memory items with homogeneous appearance; Qian et al, 2020 ; Qian & Zhang, 2019 ; Zhang, Gao, & Qian, 2020 ) may enhance their perceptual separateness, and the memory performance for their depth locations may be further improved. Indeed, in real life we can almost always memorize the spatial locations of multiple objects that have various colors, shapes, and sizes.…”

The Short-Term Retention of Depth

“…Qian and colleagues [5,[41][42][43] tested whether VWM stores depth information using CDT. In [5], from one to six blue squares were presented for 800 ms, each in a different stereoscopically-defined depth plane, and probed 900 ms later.…”