When less is more: Line-drawings lead to greater boundary extension than color photographs

Setting the scene for boundary extension: Methods, findings, connections, and theories

A previously viewed scene is often remembered as containing a larger extent of the background than was actually present, and information that was likely present just outside the boundaries of that view is often incorporated into the representation of that scene. This has been referred to as boundary extension. Methodologies used in studies on boundary extension (terminology, stimulus presentation, response measures) are described. Empirical findings regarding effects of characteristics of the stimulus (whether the stimulus depicts a scene, semantics of the scene, view angle, object size, object cropping, object orientation, object color, number of objects, depth of field, object distance, viewpoint production, scene orientation, motion, faces, emotions, modality, whether the scene is multimodal), characteristics of the display (aperture shape, aperture size, target duration, retention interval), and characteristics of the observer (allocation of attention, imagination, age, expectations and strategies, eye fixation, eye movements, monocular or binocular view, vantage point, confinement, prior exposure, expertise, arousal, pathology) on boundary extension are reviewed. Connections of boundary extension to other cognitive phenomena and processes (evolutionary adaptation, Gestalt principles, illusions, psychophysics, invariant physical principles, aesthetics, temporal boundary extension, normalization) are noted, and theories and theoretical considerations regarding boundary extension (multisource model, boundary transformation, mental imagery, 4E cognition, cognitive modularity, neurological mechanisms of scene representation) are discussed.

Numerosity Perception in Peripheral Vision

Peripheral vision has different functional priorities for mammals than foveal vision. One of its roles is to monitor the environment while central vision is focused on the current task. Becoming distracted too easily would be counterproductive in this perspective, so the brain should react to behaviourally relevant changes. Gist processing is good for this purpose, and it is therefore not surprising that evidence from both functional brain imaging and behavioural research suggests a tendency to generalize and blend information in the periphery. This may be caused by the balance of perceptual influence in the periphery between bottom-up (i.e., sensory information) and top-down (i.e., prior or contextual information) processing channels. Here, we investigated this interaction behaviourally using a peripheral numerosity discrimination task with top-down and bottom-up manipulations. Participants compared numerosity between the left and right peripheries of a screen. Each periphery was divided into a centre and a surrounding area, only one of which was a task relevant target region. Our top-down task modulation was the instruction which area to attend - centre or surround. We varied the signal strength by altering the stimuli durations i.e., the amount of information presented/processed (as a combined bottom-up and recurrent top-down feedback factor). We found that numerosity perceived in target regions was affected by contextual information in neighbouring (but irrelevant) areas. This effect appeared as soon as stimulus duration allowed the task to be reliably performed and persisted even at the longest duration (1 s). We compared the pattern of results with an ideal-observer model and found a qualitative difference in the way centre and surround areas interacted perceptually in the periphery. When participants reported on the central area, the irrelevant surround would affect the response as a weighted combination - consistent with the idea of a receptive field focused in the target area to which irrelevant surround stimulation leaks in. When participants report on surround, we can best describe the response with a model in which occasionally the attention switches from task relevant surround to task irrelevant centre - consistent with a selection model of two competing streams of information. Overall our results show that the influence of spatial context in the periphery is mandatory but task dependent.

Boundary Extension Effect Remembering Different Content Pictures

The goal of this study was to investigate in which cases boundary extension occurs when repainting visual images with different content from your memory. The method that was used in this study is based on a meta-analysis conducted by Hubbard et al. (2010). The method consists of 12 stimuli (dimensions 10x15 cm), which show a photographic image or sketch of a painting. Presented stimuli contain images with different content – finished object, object with its corners removed, emotionally neutral, positive and negative object, moving object; 120 respondents participated in the study, their age ranged from 14 to 45 years old (average age – 25,6). The first hypothesis, stating that boundary extension is more frequent with images of objects with removed corners than those of finished objects repainted from memory, was confirmed. The second hypothesis, stating that boundary extension is more frequent with images of emotionally neutral objects than those of emotionally positive or intense objects repainted from memory, was confirmed. The third hypothesis, stating that boundary extension while repainting images that contain containing moving objects, form memory, unfolds from the expected direction of object movement – the left side, was not confirmed. It was found that boundary extension unfolded at the top of a painting (bird) and at the bottom of a painting (vehicle). The fourth hypothesis was partly confirmed – that boundary extension while repainting images from memory with different content stimuli is more likely to happen among teenagers (years 14–19). The central tendency is more likely among younger adults (20–30), and boundary restriction – among older adults (31–45). The fifth hypothesis was confirmed. As expected, boundary extension when repainting images of different content from memory more often occurrs with women than men. The sixth hypothesis, stating that boundary extensions are more often when repainting images from memory that were painted and are not photographical images, was not confirmed.

Boundaries Extend and Contract in Scene Memory Depending on Image Properties

Boundary extension, a memory distortion in which observers consistently recall a scene with visual information beyond its boundaries, is widely accepted across the psychological sciences as a phenomenon revealing fundamental insight into memory representations [1-3], robust across paradigms [1, 4] and age groups [5-7]. This phenomenon has been taken to suggest that the mental representation of a scene consists of an intermingling of sensory information and a schema that extrapolates the views of a presented scene [8], and it has been used to provide evidence for the role of the neocortex [9] and hippocampus [10, 11] in the schematization of scenes during memory. However, the study of boundary extension has typically focused on object-oriented images that are not representative of our visuospatial world. Here, using a broad set of 1,000 images tested on 2,000 participants in a rapid recognition task, we discover "boundary contraction" as an equally robust phenomenon. Further, image composition largely drives whether extension or contraction is observed-although object-oriented images cause more boundary extension, scene-oriented images cause more boundary contraction. Finally, these effects also occur during drawing tasks, including a task with minimal memory load-when participants copy an image during viewing. Collectively, these results show that boundary extension is not a universal phenomenon and put into question the assumption that scene memory automatically combines visual information with additional context derived from internal schema. Instead, our memory for a scene may be largely driven by its visual composition, with a tendency to extend or contract the boundaries equally likely.

Effect of contextual knowledge on spatial layout extrapolation

Boundary extension (BE) refers to the tendency to remember a previously perceived scene with a greater spatial expanse. This phenomenon is described as resulting from different sources of information: external (i.e., visual) and internally driven (i.e., amodal, conceptual, and contextual) information. Although the literature has emphasized the role of top-down expectations to account for layout extrapolation, their effect has rarely been tested experimentally. In this research, we attempted to determine how visual context affects BE, as a function of scene exposure duration (long, short). To induce knowledge about visual context, the memorization phase of the camera distance paradigm was preceded by a preexposure phase, during which each of the to-be-memorized scenes was presented in a larger spatial framework. In an initial experiment, we examined the effect of contextual knowledge with presentation duration, allowing for in-depth processing of visual information during encoding (i.e., 15 s). The results indicated that participants exposed to the preexposure showed decreased BE, and displayed no directional memory error in some conditions. Because the effect of context is known to occur at an early stage of scene perception, in a second experiment we sought to determine whether the effect of a preview occurs during the first fixation on a visual scene. The results indicated that BE seems not to be modulated by this factor at very brief presentation durations. These results are discussed in light of current visual scene representation theories.

Effect of Expertise on Boundary Extension in Approach Sequences

In a constantly changing environment, one of the conditions for adaptation is based on the visual system’s ability to realize predictions. In this context, a question that arises is the evolution of the processes allowing anticipation with regard to the acquisition of knowledge relative to specific situations. We sought to study this question by focusing on boundary extension, the tendency to overestimate the scope of a previously perceived scene. We presented to novice, beginner, and expert car drivers road scenes in the form of approach sequences constituting very briefly displayed photographs (i.e., 250 milliseconds each), in order to determine the effect of expertise at an early stage of scene perception. After three presentations, participants had to judge whether a fourth photograph was the same, closer up, or further away than the third one. When experts and beginners showed a classical boundary extension effect, novices presented no directional memory distortion. Different hypotheses are discussed.

Anticipatory scene representation in preschool children's recall and recognition memory

Behavioral and neuroscience research on boundary extension (false memory beyond the edges of a view of a scene) has provided new insights into the constructive nature of scene representation, and motivates questions about development. Early research with children (as young as 6-7 years) was consistent with boundary extension, but relied on an analysis of spatial errors in drawings which are open to alternative explanations (e.g. drawing ability). Experiment 1 replicated and extended prior drawing results with 4-5-year-olds and adults. In Experiment 2, a new, forced-choice immediate recognition memory test was implemented with the same children. On each trial, a card (photograph of a simple scene) was immediately replaced by a test card (identical view and either a closer or more wide-angle view) and participants indicated which one matched the original view. Error patterns supported boundary extension; identical photographs were more frequently rejected when the closer view was the original view, than vice versa. This asymmetry was not attributable to a selection bias (guessing tasks; Experiments 3-5). In Experiment 4, working memory load was increased by presenting more expansive views of more complex scenes. Again, children exhibited boundary extension, but now adults did not, unless stimulus duration was reduced to 5 s (limiting time to implement strategies; Experiment 5). We propose that like adults, children interpret photographs as views of places in the world; they extrapolate the anticipated continuation of the scene beyond the view and misattribute it to having been seen. Developmental differences in source attribution decision processes provide an explanation for the age-related differences observed.

Visual, haptic and bimodal scene perception: evidence for a unitary representation

Participants studied seven meaningful scene-regions bordered by removable boundaries (30s each). In Experiment 1 (N = 80) participants used visual or haptic exploration and then minutes later, reconstructed boundary position using the same or the alternate modality. Participants in all groups shifted boundary placement outward (boundary extension), but visual study yielded the greater error. Critically, this modality-specific difference in boundary extension transferred without cost in the cross-modal conditions, suggesting a functionally unitary scene representation. In Experiment 2 (N = 20), bimodal study led to boundary extension that did not differ from haptic exploration alone, suggesting that bimodal spatial memory was constrained by the more "conservative" haptic modality. In Experiment 3 (N = 20), as in picture studies, boundary memory was tested 30s after viewing each scene-region and as with pictures, boundary extension still occurred. Results suggest that scene representation is organized around an amodal spatial core that organizes bottom-up information from multiple modalities in combination with top-down expectations about the surrounding world.

Seek and you shall remember: scene semantics interact with visual search to build better memories

Memorizing critical objects and their locations is an essential part of everyday life. In the present study, incidental encoding of objects in naturalistic scenes during search was compared to explicit memorization of those scenes. To investigate if prior knowledge of scene structure influences these two types of encoding differently, we used meaningless arrays of objects as well as objects in real-world, semantically meaningful images. Surprisingly, when participants were asked to recall scenes, their memory performance was markedly better for searched objects than for objects they had explicitly tried to memorize, even though participants in the search condition were not explicitly asked to memorize objects. This finding held true even when objects were observed for an equal amount of time in both conditions. Critically, the recall benefit for searched over memorized objects in scenes was eliminated when objects were presented on uniform, non-scene backgrounds rather than in a full scene context. Thus, scene semantics not only help us search for objects in naturalistic scenes, but appear to produce a representation that supports our memory for those objects beyond intentional memorization.