Systematic transition from boundary extension to contraction along an object-to-scene continuum

Abstract

After viewing a picture of an environment, our memory of it typically extends beyond what was presented, a phenomenon referred to as boundary extension. But, sometimes memory errors show the opposite pattern-boundary contraction-and the relationship between these phenomena is controversial. We constructed virtual three-dimensional environments and created a series of views at different distances, from object close-ups to wide-angle indoor views, and tested for memory errors along this object-to-scene continuum. Boundary extension was evident for close-scale views and transitioned parametrically to boundary contraction for far-scale views. However, this transition point was not tied to a specific position in the environment (e.g., the point of reachability). Instead, it tracked with judgments of the best-looking view of the environment, in both rich-object and low-object environments. We offer a dynamic-tension account, where competition between object-based and scene-based affordances determines whether a view will extend or contract in memory. This study demonstrates that boundary extension and boundary contraction are not two separate phenomena but rather two parts of a continuum, suggesting a common underlying mechanism. The transition point between the two is not fixed but depends on the observer's judgment of the best-looking view of the environment. These findings provide new insights into how we perceive and remember a view of environment.

Figure 1.

Stimuli. (A) Example images along the 30-point continuum from two different environments. (B) Schematic of the 3D environment in Unity with views taken from a camera from the front to the back of the scene. The FOV of the camera and the rotation angle of the camera were gradually changed to interpolate between an object-centered view of a single central object and a wider field of view of the entire scene.

Figure 2.

Memory Experiment paradigm and results. (A) Procedure of the Memory Experiment. The first image was shown for 250 ms followed by 250 ms of mosaic-scrambled masks. The second image was presented for 1 second, and participants were asked to answer whether the second image was closer or farther compared to the first image. Unbeknownst to participants, the second image was always identical to the first one. (B) Memory distortion scores averaged within each position. The error bars represent the standard error of the mean. The negative score indicates boundary extension, and the positive score indicates boundary contraction. Overall, there was a smooth transition from boundary extension to contraction as it changed from object-centered to scene-centered images.

Figure 3.

Transition range examples and results from reachability and goodness-of-view judgments. (A) Examples of the memory transition points from four different environments. (B) The reachability judgment score averaged by each position and an example image of the transition point. The negative score represents within-reach judgments, the positive represents out-of-reach judgments, and the zero represents the transition point of subjective reachability. (C) The goodness-of-view judgment score averaged by each position and an example image of the transition point. The negative score represents a preference to step backward, the positive represents a preference to step forward, and the zero represents the most preferred (“looks good”) view. For both (B) and (C), a vertical gradient bar indicates a transitional range (bootstrap 95% CI), and the horizontal bar on top of the plot shows the transition range from memory distortions (light blue).

Figure 4.

Low-object environments. All of the small and manipulable objects were removed from the rich-object environments, leaving the immovable surfaces and furniture-like structure present such as kitchen countertops or cabinets. As a result, two sets of environments shared the same spatial layout but differed substantially in their object content.

Figure 5.

Low-object environment results and transition points. (A) The mean score by position from each paradigm. Positions around zero (y-axis) indicate the transition point, and a vertical gradient bar represents the transitional region (bootstrap 95% CI). Compared to the rich-object environments (Figures 2 and 3), the transition region shifted much further in the memory distortion and goodness-of-view judgments. However, the transition region of subjective reachability remained in relatively similar positions regardless of the stimulus set. (B) Examples of transition points from each paradigm. Critically, the transition range of goodness of view showed much closer resemblance to that of memory distortion, favoring the canonical view account.