
Filipp SchmidtUniversity of Giessen | JLU · Department of Psychology
Filipp Schmidt
PhD
About
103
Publications
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Introduction
I am a postdoctoral research fellow in the lab of Prof. Dr. Roland W. Fleming at Justus-Liebig-Universität Gießen. I study the visual perception of objects, shape and materials, using a combination of computer graphics, psychophysics and computational modelling.
Publications
Publications (103)
The world is abundant with diverse materials, each possessing unique surface appearances that play a crucial role in our daily perception and understanding of their properties. Despite advancements in technology enabling the capture and realistic reproduction of material appearances for visualization and quality control, the interoperability of mat...
Previous research on attention to fear-relevant stimuli has largely focused on static pictures or drawings, and thus did not consider the potential effect of natural motion. Here, we aimed to investigate the effect of motion on attentional capture in spider-fearful and non-fearful participants by using point-light stimuli and naturalistic videos. P...
Materials exhibit an extraordinary range of visual appearances. Characterizing and quantifying appearance is important not only for basic research on perceptual mechanisms but also for computer graphics and a wide range of industrial applications. Although methods exist for capturing and representing the optical properties of materials and how they...
Previous research on attention to fear-relevant stimuli has largely focused on static pictures or drawings, and thus did not consider the potential effect of natural motion. Here, we aimed to investigate the effect of motion on attentional capture in spider-fearful and non-fearful participants by using point-light stimuli and naturalistic videos. P...
Visual shape perception is central to many everyday tasks, from object recognition to grasping and handling tools.¹,²,³,⁴,⁵,⁶,⁷,⁸,⁹,¹⁰ Yet how shape is encoded in the visual system remains poorly understood. Here, we probed shape representations using visual aftereffects—perceptual distortions that occur following extended exposure to a stimulus.¹¹...
Many objects and materials in our environment are subject to transformations that alter their shape. For example, branches bend in the wind, ice melts, and paper crumples. Still, we recognize objects and materials across these changes, suggesting we can distinguish an object's original features from those caused by the transformations ("shape sciss...
Humans categorize both familiar and novel objects quickly and consistently. Many theories posit that we achieve this by forming category boundaries around the perceived object in a high-dimensional psychological feature space. As of now, these spaces are mostly theoretical constructs without appropriate empirical methods available to probe them. He...
Many biological homologies were discovered before Darwin and without agreed criteria. Paradigmatic examples include the phylogenetic homology of mammalian forelimb bones and the serial homology of floral organs in waterlilies. It is generally assumed that perceiving similarities intuitively was the first step towards establishing morphological homo...
Materials exhibit an extraordinary range of visual appearances. Characterising and quantifying appearance is important not only for basic research on perceptual mechanisms, but also for computer graphics and a wide range of industrial applications. While methods exist for capturing and representing the optical properties of materials and how they v...
Shape perception is essential for numerous everyday behaviors from object recognition to grasping and handling objects. Yet how the brain encodes shape remains poorly understood. Here, we probed shape representations using visual aftereffects (perceptual distortions that occur following extended exposure to a stimulus) to resolve a long-standing de...
Observers asked to indicate the smaller of two images on a screen are slowed down by mismatching real-world sizes of the depicted objects (e.g. when the smaller image shows a tree and the larger image a broccoli). This kind of familiar-size Stroop effect is also observed for ‘texform’ images, which only preserve unrecognizable shape features of obj...
Visually categorizing and comparing materials is crucial for our everyday behaviour. Given the dramatic variability in their visual appearance and functional significance, what organizational principles underly the internal representation of materials? To address this question, here we use a large-scale data-driven approach to uncover the core late...
Responding adequately to the behaviour of human and non-human animals in our environment has been crucial for our survival. This is also reflected in our exceptional capacity to detect and interpret biological motion signals. However, even though our emotions have specifically emerged as automatic adaptive responses to such vital stimuli, few studi...
Plants and animals are among the most behaviorally significant superordinate categories for humans. Visually assigning objects to such high-level classes is challenging because highly distinct items must be grouped together (e.g., chimpanzees and geckos) while more similar items must sometimes be separated (e.g., stick insects and twigs). As both a...
Humans have the amazing ability to learn new visual concepts from just a single exemplar. How we achieve this remains mysterious. State-of-the-art theories suggest observers rely on internal 'generative models', which not only describe observed objects, but can also synthesize novel variations. However, compelling evidence for generative models in...
Many objects in our visual environment will appear to us either as a consequence of “intelligent” design—the purposeful action of an animal mind—or as a consequence of self-organization in response to nature's forces—for example, wind or gravity. Here, the origin of this distinction is studied by collecting human judgements about skeletal represent...
Many natural materials have complex, multi-scale structures. Consequently, the inferred identity of a surface can vary with the assumed spatial scale of the scene: a plowed field seen from afar can resemble corduroy seen up close. We investigated this ‘material-scale ambiguity’ using 87 photographs of diverse materials (e.g., water, sand, stone, me...
While scene context is known to facilitate object recognition, little is known about which contextual “ingredients” are at the heart of this phenomenon. Here, we address the question of whether the materials that frequently occur in scenes (e.g., tiles in a bathroom) associated with specific objects (e.g., a perfume) are relevant for the processing...
The development of material property perception for grasping objects is not well explored during early childhood. Therefore, we investigated infants', 3-year-old children's, and adults' unimanual grasping behavior and reaching kinematics for objects of different rigidity using a 3D motion capture system. In Experiment 1, 11-month-old infants and fo...
Many natural materials have complex, multi-scale structures. Consequently, the apparent identity of a surface can vary with the assumed spatial scale of the scene: a plowed field seen from afar can resemble corduroy seen up close. We investigated this ‘material-scale ambiguity’ using 87 photographs of diverse materials (e.g., water, sand, stone, me...
While scene context is known to facilitate object recognition, little is known about whichcontextual “ingredients” are at the heart of this phenomenon. Here, we address the question ofwhether the materials that frequently occur in scenes (e.g., tiles in bathroom) associated withspecific objects (e.g., a perfume) are relevant for processing of that...
Shape is a defining feature of objects, and human observers can effortlessly compare shapes to determine how similar they are. Yet, to date, no image-computable model can predict how visually similar or different shapes appear. Such a model would be an invaluable tool for neuroscientists and could provide insights into computations underlying human...
Humans have the striking ability to learn and generalize new visual concepts from just a single exemplar. We suggest that when presented with a novel object, observers identify its significant features and infer a generative model of its shape, allowing them to mentally synthesize plausible variants. To test this, we showed participants abstract 2D...
The visual system has to distinguish between information that is relevant and irrelevant for current behavioral goals. This is especially important in automatized responses. Here, we study how task-irrelevant distractors with task-relevant features gain access to speeded, automatized motor responses in a response-priming paradigm. In two tasks, we...
Mobile applications are increasingly part of mental health programs and various apps have been developed for treating anxiety disorders. Typically, they aim to improve anxiety symptoms via established CBT techniques, such as exposure principles, which are considered extremely unpleasant for fearful individuals. We combined in a mobile application e...
In this Methods paper, we discuss and illustrate a unifying, principled way to analyze response time data from psychological experiments-and all other types of time-to-event data. We advocate the general application of discrete-time event history analysis (EHA) which is a well-established, intuitive longitudinal approach to statistically describe a...
Establishing correspondence between objects is fundamental for object constancy, similarity perception and identifying transformations. Previous studies measured point-to-point correspondence between objects before and after rigid and non-rigid shape transformations. However, we can also identify ‘similar parts’ on extremely different objects, such...
Material perception — the visual perception of stuff — is an emerging field in vision research. We recognize materials from shape, color and texture features. This paper is a selective review and discussion of how artists have been using shape features to evoke vivid impressions of specific materials and material properties. A number of examples ar...
Object shape is an important cue to material identity and for the estimation of material properties. Shape features can affect material perception at different levels: at a microscale (surface roughness), mesoscale (textures and local object shape), or megascale (global object shape) level. Examples for local shape features include ripples in drape...
With the advent of deep convolutional neural networks, machines now rival humans in terms of object categorization. The neural networks solve categorization with a hierarchical organization that shares a striking resemblance to their biological counterpart, leading to their status as a standard model of object recognition in biological vision. Desp...
Shape is a defining feature of objects. Yet, no image-computable model accurately predicts how similar or different shapes appear to human observers. To address this, we developed a model (ShapeComp), based on over 100 shape features (e.g., area, compactness, Fourier descriptors). When trained to capture the variance in a database of >25,000 animal...
One aspect of human vision unmatched by machines is the capacity to generalize from few samples. Observers tend to know when novel objects are in the same class despite large differences in shape, material or viewpoint. A major challenge in studying such generalization is that participants can see each novel sample only once. To overcome this, we u...
Background and objectives:
The fast detection of and response to threatening stimuli is an important task of the human visual and motor systems, and is especially challenging when stimuli are ambiguous. This study investigates the perception, evaluation and fast response to ambiguous natural spider stimuli in spider-fearful and non-anxious partici...
Shape-deforming processes (e.g., squashing, bending, twisting) can radically alter objects’ shapes. After such a
transformation, some features are due to the object’s original form, while others are due to the transformation,
yet it is challenging to separate the two. We tested whether observers can distinguish the causal origin of
different feature...
Every object acquires its shape from some kind of generative process, such as manufacture, biological growth, or self-organization, in response to external forces. Inferring such generative processes from an observed shape is computationally challenging because a given process can lead to radically different shapes, and similar shapes can result fr...
How do individuals with obsessive-compulsive disorder (OCD) process and respond to images of rotten food or dirty toilets? In contrast to other fear-related disorders, evidence for attentional biases and preferential processing of disorder-related stimuli in samples of OCD is mixed. To address methodological problems of previous studies and to incr...
An important task of human visual cognition is to make inferences about properties of objects. One such property is an object's causal history: what happened to the object in its past (e.g., “this paper has been folded”). There is relatively little research on whether and how we make such inferences. We took photographs of objects from six differen...
Raw free naming data from Experiment 1.
The different panels show naming responses for the different (A) materials, and (B) transformations. The bars plot the frequency of naming responses [percent] with the actual material/transformation in black.
(PDF)
Paired t-tests comparing ratings between different transformations in the transformation rating task.
** indicates p < .001 and * indicates p < .05.
(PDF)
Paired t-tests comparing ratings between different transformations in the 4-AFC task.
** indicates p < .001 and * indicates p < .05.
(PDF)
Paired t-tests comparing ratings between different materials in the material rating task.
** indicates p < .001 and * indicates p < .05.
(PDF)
Paired t-tests comparing ratings between different transformations in the material rating task.
** indicates p < .001 and * indicates p < .05.
(PDF)
Paired t-tests comparing ratings between different materials in the transformation rating task.
** indicates p < .001 and * indicates p < .05.
(PDF)
Paired t-tests comparing ratings between different materials in the transformation rating task within the class of bend objects.
** indicates p < .001 and * indicates p < .05.
(PDF)
Paired t-tests comparing ratings between different materials in the transformation rating task.
** indicates p < .001 and * indicates p < .05.
(PDF)
Paired t-tests comparing ratings between different materials in the transformation rating task within the class of bend objects.
** indicates p < .001 and * indicates p < .05.
(PDF)
Paired t-tests comparing ratings between different materials in the transformation rating task within the class of folded objects.
** indicates p < .001 and * indicates p < .05.
(PDF)
In response priming tasks, speeded responses are performed toward target stimuli preceded by prime stimuli. Responses are slower and error rates are higher when prime and target are assigned to different responses, compared to assignment to the same response, and those priming effects increase with prime-target SOA. Here, we generalize Vorberg et a...
Superordinate visual classification—for example, identifying an image as ''animal,'' ''plant,'' or ''mineral''—is computationally challenging because radically different items (e.g., ''octopus,'' ''dog'') must be grouped into a common class (''animal''). It is plausible that learning superordinate categories teaches us not only the membership of pa...
Visually inferring the stiffness of objects is important for many tasks but is challenging because, unlike optical properties (e.g., gloss), mechanical properties do not directly affect image values. Stiffness must be inferred
either (a) by recognizing materials and recalling their properties (associative approach) or (b) from shape and
motion cues...
Nonrigid materials, such as jelly, rubber, or sponge move and deform in distinctive ways depending on their stiffness. Which cues do we use to infer stiffness? We simulated cubes of varying stiffness and optical appearance (e.g., wood, metal, wax, jelly) being subjected to two kinds of deformation: (a) a rigid cylinder pushing downwards into the cu...
Visual perception is not instantaneous; the perceptual representation of our environment builds up over time. This can strongly affect our responses to visual stimuli. Here, we study the temporal dynamics of visual processing by analyzing the time course of priming effects induced by the well-known Ebbinghaus illusion. In slower responses, Ebbingha...
One of the main functions of vision is to represent object shape. Most theories of shape perception focus exclusively on geometrical computations (e.g., curvatures, symmetries, axis structure). Here, however, we find that shape representations are also profoundly influenced by an object’s causal origins: the processes in its past that formed it. Ob...
Morphogenesis—or the origin of complex natural form—has long fascinated researchers from practically every branch of science. However, we know practically nothing about how we perceive and understand such processes. Here, we measured how observers visually infer shape-transforming processes. Participants viewed pairs of objects (‘before’ and ‘after...
Selecting appropriate stimuli is a major challenge of affective research. Although several standardized databases for affective pictures exist, none of them focus on discrete emotions such as disgust. Validated pictures inducing discrete emotions are still limited, and this presents a problem for researchers interested in studying different facets...
In contour integration, increased difficulty in detection and shape discrimination of a chain of parallel elements (a ladder contour) compared to collinear elements (a snake contour) suggests more extensive processing of ladders than of snakes. In addition, conceptual similarities between ladders and textures -- which also involve grouping of paral...
Objects in our environment are subject to manifold transformations, either of the physical objects themselves or of the object images on the retina. Despite drastic effects on the objects' physical appearances, we are often able to identify stable objects across transformations and have strong subjective impressions of the transformations themselve...
Morphogenesis—or the origin of complex natural form—has long fascinated researchers from practically every branch of science. Despite dramatic advances in our understanding of how physical and biological processes generate complex shapes like crystals, lungs, or sunflowers, we know practically nothing about how the human mind perceives and understa...
Visuomotor Processing and Perception of Natural Morphed Images in Spider Phobics.
Many objects in our environment undergo visible processes of change, such as growth, weathering, bending or crumpling. Despite huge resulting changes in appearance, we can often identify both the object across the transformation and the transformation that has been applied to it, as if the visual system decomposes the object's features into distinc...
Objects in our environment are subject to manifold transformations, from simple rigid changes like rotation or scaling, to complex processes like twisting, bending or biological growth. Although many transformations have drastic effects on an object's physical appearance, we are often able to identify stable objects across such changes, and in many...
This study investigates the interpretative bias in spider phobia with respect to rapid visuomotor processing. We compared perception, evaluation, and visuomotor processing of ambiguous schematic stimuli between spider-fearful and control participants. Stimuli were produced by gradually morphing schematic flowers into spiders. Participants rated the...