Matthew X. Lowe

Feature diagnosticity and task context shape activity in human scene-selective cortex.

Scenes are constructed from multiple visual features, yet previous research investigating scene processing has often focused on the contributions of single features in isolation. In the real world, features rarely exist independently of one another and likely converge to inform scene identity in unique ways. Here, we utilize fMRI and pattern classification techniques to examine the interactions between task context (i.e., attend to diagnostic global scene features; texture or layout) and high-level scene attributes (content and spatial boundary) to test the novel hypothesis that scene-selective cortex represents multiple visual features, the importance of which varies according to their diagnostic relevance across scene categories and task demands. Our results show for the first time that scene representations are driven by interactions between multiple visual features and high-level scene attributes. Specifically, univariate analysis of scene-selective cortex revealed that task context and feature diagnosticity shape activity differentially across scene categories. Examination using multivariate decoding methods revealed results consistent with univariate findings, but also evidence for an interaction between high-level scene attributes and diagnostic visual features within scene categories. Critically, these findings suggest visual feature representations are not distributed uniformly across scene categories but are shaped by task context and feature diagnosticity. Thus, we propose that scene-selective cortex constructs a flexible representation of the environment by integrating multiple diagnostically relevant visual features, the nature of which varies according to the particular scene being perceived and the goals of the observer.

Neural representation of geometry and surface properties in object and scene perception

&NA; Multiple cortical regions are crucial for perceiving the visual world, yet the processes shaping representations in these regions are unclear. To address this issue, we must elucidate how perceptual features shape representations of the environment. Here, we explore how the weighting of different visual features affects neural representations of objects and scenes, focusing on the scene‐selective parahippocampal place area (PPA), but additionally including the retrosplenial complex (RSC), occipital place area (OPA), lateral occipital (LO) area, fusiform face area (FFA) and occipital face area (OFA). Across three experiments, we examined functional magnetic resonance imaging (fMRI) activity while human observers viewed scenes and objects that varied in geometry (shape/layout) and surface properties (texture/material). Interestingly, we found equal sensitivity in the PPA for these properties within a scene, revealing that spatial‐selectivity alone does not drive activation within this cortical region. We also observed sensitivity to object texture in PPA, but not to the same degree as scene texture, and representations in PPA varied when objects were placed within scenes. We conclude that PPA may process surface properties in a domain‐specific manner, and that the processing of scene texture and geometry is equally‐weighted in PPA and may be mediated by similar underlying neuronal mechanisms.

Selective scene perception deficits in a case of topographical disorientation

Topographical disorientation (TD) is a neuropsychological condition characterized by an inability to find ones way, even in familiar environments. One common contributing cause of TD is landmark agnosia, a visual recognition impairment specific to scenes and landmarks. Although many cases of TD with landmark agnosia have been documented, little is known about the perceptual mechanisms which lead to selective deficits in recognizing scenes. In the present study, we test LH, a man who exhibits TD and landmark agnosia, on measures of scene perception that require selectively attending to either the configural or surface properties of a scene. Compared to healthy controls, LH demonstrates perceptual impairments when attending to the configuration of a scene, but not when attending to its surface properties, such as the pattern of the walls or whether the ground is sand or grass. In contrast, when focusing on objects instead of scenes, LH demonstrates intact perception of both geometric and surface properties. This study demonstrates that in a case of TD and landmark agnosia, the perceptual impairments are selective to the layout of scenes, providing insight into the mechanism of landmark agnosia and scene-selective perceptual processes.

Sensory Processing Patterns Predict the Integration of Information Held in Visual Working Memory

Given the limited resources of visual working memory, multiple items may be remembered as an averaged group or ensemble. As a result, local information may be ill-defined, but these ensemble representations provide accurate diagnostics of the natural world by combining gist information with item-level information held in visual working memory. Some neurodevelopmental disorders are characterized by sensory processing profiles that predispose individuals to avoid or seek-out sensory stimulation, fundamentally altering their perceptual experience. Here, we report such processing styles will affect the computation of ensemble statistics in the general population. We identified stable adult sensory processing patterns to demonstrate that individuals with low sensory thresholds who show a greater proclivity to engage in active response strategies to prevent sensory overstimulation are less likely to integrate mean size information across a set of similar items and are therefore more likely to be biased away from the mean size representation of an ensemble display. We therefore propose the study of ensemble processing should extend beyond the statistics of the display, and should also consider the statistics of the observer. (PsycINFO Database Record

Processing context: Asymmetric interference of visual form and texture in object and scene interactions.

Substantive evidence has demonstrated that scene-centered global image features influence the processing of objects embedded in complex visual scenes. Conversely, a growing body of work suggests that relevant object information may inherently influence diagnostic global scene statistics used in rapid scene categorization. Here, we investigate the potential effects of interference in object-scene perception when attending to form and texture in both simple figure-ground representations and more complex object-background scenes. Results reveal asymmetric interference in the perception of form and texture in object and scene processing: Inconsistent scene texture interfered with the classification of object texture, and inconsistent object form interfered with the classification of scene form, but not vice versa. These findings contribute to our understanding of the interactions between an object and its environment, and further inform our knowledge of the visual features which influence interactivity in object and scene perception.

Relating the perception of visual ensemble statistics to individual levels of autistic traits

Integrating information across the visual field into an ensemble (e.g., seeing the forest from the trees) is an effective strategy to efficiently process the visual world, and one that is often impaired in autism spectrum disorder. Individual differences in sensory processing predict ensemble encoding, providing a potential mechanism for differing perceptual strategies across individuals, and possibly across diagnostic groups exhibiting atypical sensory processing. Here, we explore whether ensemble encoding is associated with traits associated with autism spectrum disorder (ASD). Participants (N=68) were presented with an ensemble display consisting of circles of varying sizes and colors, and were asked to remember the size of the red and blue circles, while ignoring the green circles. Participants were then cued to a target location after a brief delay, and instructed to report the remembered size of the circle they had previously viewed in that location, as ensemble information commonly biases memory for individual objects toward the probed mean of a set of similar objects. The Autism-spectrum Quotient (AQ) was completed to measure each individual’s level of autistic traits. We found that an individual’s level of ensemble perception, measured as their bias toward the probed mean, was negatively associated with a higher level of ASD traits. These results suggest that individuals with higher levels of ASD traits are less likely to integrate perceptual information. These findings may shed light on different perceptual processing within the autism spectrum, and provide insight into the relationship between individual differences and ensemble encoding.

Texture and Spatial Layout Converge in Human Scene-Selective Cortex

Scenes are composed of multiple visual features, yet previous research investigating scene representation has often focused on the unique contributions of single features, such as spatial layout and texture. However, these features rarely exist in isolation. As texture can provide depth and contour information necessary for spatial perception, a dynamic and convergent relationship may exist between texture and spatial layout. Yet it has been unclear how this relationship would manifest in scene-selective cortex. Since texture is typically more diagnostic of place identity in natural compared with non-natural scenes, and spatial layout is typically less ambiguous in non-natural compared with natural scenes, we tested the hypothesis that PPA would show equal sensitivity to manipulations of texture and spatial layout in natural scenes, but would show greater sensitivity to layout in non-natural scenes. Using fMRI, we examined brain activity in areas of scene-selective cortex while participants performed a matching task when attending to either the layout or texture of four different scene categories which varied by spatial boundary (open vs. closed) and content (natural vs. non-natural). As predicted, univariate analysis in PPA revealed equal sensitivity to texture and layout in natural scenes, but less sensitivity to texture in non-natural scenes. Importantly, multivariate analyses revealed decoding accuracy significantly above chance in PPA for both spatial boundary (only in non-natural scenes, which is consistent with our univariate results) and content, replicating previous studies and validating the use of our stimulus set. Our findings demonstrate that scene representation in PPA is not based solely on spatial structure, and may be driven by interactions between diagnostic visual features such as texture and spatial layout. Therefore, we propose extending the study of scene perception to not only investigate which individual features are represented in scene-selective cortex, but how these features converge to define place identity. Meeting abstract presented at VSS 2015.

Perceiving the global: The role of surface texture consistency in object and background perception

Seminal work on global processing has suggested that the precedence of global image features is an inherent property of visual perception. Consequently, interference from global percepts may influence the perception of local elements. Investigations of scene processing have been consistent with this suggestion, demonstrating that the parahippocampal place area (PPA) represents scenes by processing global spatial properties. Recent investigations have further revealed that PPA is sensitive to processing non-spatial visual cues (such as surface texture) in both object and scene perception. In the present study, we investigated potential global interference effects in objectscene perception when attending to spatial and non-spatial visual features in both simple figureground representations and more complex real-world scenes. Results revealed that non-spatial surface properties such as texture can form a contextual link between the processing of object and background information in scene perception, and this interactive processing proceeds from the global to local scale of attention.