Biology subjects

Doerschner, K.

Publications and source records attributed to Doerschner, K..

12 recordsLinked to original sources

bioRxiv2026

Crossmodal Expectations in Material Perception

Humans rely on multiple sensory modalities, such as vision, audition, and touch, to perceive materials in everyday life. Previous research shows that multisensory perception leads to facilitation, yet the mechanisms responsible for this facilitation remain poorly understood. One potential mechanism is crossmodal prediction, whereby input from one modality generates predictions about another. While substantial research on multisensory facilitation has focused on bottom-up processes, such as spatial, temporal, and semantic congruency, the role of crossmodal predictions, particularly in material perception, has received little attention. To address this gap, we conducted two experiments, a reaction time task and a material rating task, in which participants viewed computer-generated animations of familiar objects being dropped to the ground. The paradigm exploited the natural temporal structure of impact events: pre-impact visual appearance provides information about an objects material and therefore can generate expectations about the forthcoming impact sound. Critically, participants saw the event only until before the impact, after which the video was masked. Thus, vision and audition were temporally aligned but not presented concurrently, allowing us to isolate the influence of visually driven expectations on the incoming auditory information without a bottom-up conflict. In some trials, the sound matched the expected material, but in a subset, it was incongruent, violating expectations elicited by the preceding visual information. Across both experiments, participants took longer to respond on incongruent than congruent trials, suggesting increased processing demands. In the rating task, incongruent trials also shifted material judgments, such that ratings reflected a weighted combination of incoming auditory information and visually driven predictions, with large individual differences in relative cue weighting. These findings suggest that priors on material properties from one modality, specifically vision, not only establish high-level expectations within the modality about an objects future state, but also extend across modalities.

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bioRxiv2025

Perceiving Material Qualities from Moving Contours

While research on the perception of line drawings has long demonstrated the importance of contours in object recognition, recent work shows that contours can also convey material properties. For example, even simple 2D shapes with varying contours have been shown to evoke vivid impressions of different materials (Pinna & Deiana, 2015). However, such static representations capture only a single moment in time. When a material moves, its contours shift, evolve, or deform over time, creating contour motion. Does this contour motion convey diagnostic information about material properties, independent of surface appearance? Existing studies on the role of dynamic cues in material perception either use fully rendered 3D stimuli, where contour motion is confounded with rich surface information, or motion-only displays (dynamic dot stimuli or noise patches), which eliminate surface cues but also lack clearly defined contours. As a result, the relative contribution of contour motion to material perception remains unclear. To address this gap, we measured how human observers perceive materials from dynamic line drawings ("line"), compared to animations of fully textured stimuli that carry optical and motion information ("full"), as well as dynamic dot stimuli ("dot"). Stimuli were rendered versions (full, dot, line) of material animations from five material categories (jelly, liquid, smoke, fabric, and rigid-breakable). In one experiment, participants rated five material attributes (dense, flexible, wobbly, fluid, airy motion), and in a second experiment, participants were asked to choose one of the two materials that is more similar to a third material across all possible combinations. Results from both experiments consistently reveal that 1) Dynamic line drawings vividly convey mechanical material properties, and 2) the similarity in material judgments between line and full conditions was larger than that between dot and full conditions. We conclude that contour motion carries rich information about mechanical material qualities.

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bioRxiv2024

Happiness promotes global processing in haptic perception

Happy and sad mood promote global and local visual processing, respectively. However, it is unclear whether mood also affects the processing level in haptic perception. Here, we used classical music to induce happy and sad mood in blindfolded participants before they scanned 3D-printed configurations with their fingers. Additionally, we included a neutral group who did not listen to any music. Global shapes were triangles, circles, or squares (33mm) composed of smaller local relief shapes (3 mm): either triangles, circles, or squares. Participants explored a probe stimulus with identical local and global shapes, and two comparison stimuli, matching the probe in local, or global shape. They reported which comparison stimulus appeared more similar to the probe. In the sad group, participants chose the locally matching comparison more frequently than in the happy and neutral groups, revealing that sad mood promotes local processing also in touch. Overall, participants chose the globally matching comparison more often, suggesting that global processing is more prominent in touch than previously assumed.

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bioRxiv2024

Exploring For Gloss: The Role of Active Exploration in Visual Material Perception

Image motion contributes to the perception of visual material properties, and motion signals are generated during active exploration. However, little is known about how specific perceptual tasks influence the actions that generate these cues. In an experiment using virtual reality and real-time hand tracking, we investigated how the demands of perceptual tasks (e.g., judging gloss or lightness) shape exploratory behaviours. Participants either observed or actively explored objects varying in gloss and lightness while performing a matching task. We analysed how their exploration patterns varied based on the tasks. Using the same stimuli in both tasks, we found that participants explored objects more extensively when judging gloss than when judging lightness. These findings suggest a strategic prioritisation of relevant cues for gloss judgments, with participants using larger movements and object rotation to enhance viewing perspectives and highlight detection. Our findings show that exploration behaviours are task-dependent, with actions adapted to the demands of the perceptual task at hand.

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bioRxiv2023

Color appearance of iridescent objects

Iridescent objects and animals are quite mesmerizing to look at, since they feature multiple intense colors whose distribution can vary quite dramatically as a function of viewing angle. These properties make them a particularly interesting and unique stimulus to experimentally investigate the factors that contribute to single color impressions of multi-colored objects. Our stimuli were 3D printed shapes of varying complexity that were covered with three different types of iridescent coatings. For each shape-color combination, participants performed single- and multi-color matches for different views of the stationary object, as well as single color matches for a corresponding rotating stimulus. In the multi-color matching task, participants subsequently rated the size of the surface area on the object that was covered by the match-identified color. Results show that single-color appearance of iridescent objects varied with shape complexity, view, and object motion. Moreover, hue similarity of color settings in the multi color match task best predicted single color appearance, however this predictor was weaker for predicting single color matches in the motion condition. Taken together our findings suggest that the single color appearance of iridescent objects may be modulated by chromatic factors, spatial-relations and the characteristic dynamics of color changes that are typical for this type of material.

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bioRxiv2022

Unmet Expectations About Material Properties Delay Perceptual Decisions

Based on our expectations about material properties we can implicitly predict an objects future states, e.g. a wine glass falling down will break when it hits the ground. How these expectations affect relatively low level perceptual decisions, however, has not been systematically studied previously. To seek an answer to this question we conducted a behavioral experiment using animations of various familiar objects (e.g. key, wine glass etc.) freely falling and hitting the ground. During a training session participants first built expectations about the dynamic properties of those objects. Half of the participants (N=28) built expectations consistent with our daily lives (e.g. a key bounces rigidly), whereas the other half learned an anomalous behavior (e.g. a key wobbles). This was followed by experimental sessions, in which expectations were unmet in 20% of the trials. In both training and experimental sessions, participants task was to report whether the objects broke or not upon hitting the ground. Critically a specific object always remained intact or broke, only the manner with which it did so differed. For example, a key could wobble or remain rigid, but it never broke. We found that participants reaction times were longer when expectations were unmet even when those expectations were anomalous and learned during the training session. Furthermore, we found an interplay between long-term and newly learned expectations, which could be predicted by a Bayesian updating approach. Overall, our results show that expectations about material properties can have an impact on relatively low-level perceptual decision making processes.

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bioRxiv2021

Materials in action: The look and feel of soft

The softness of objects can be perceived through several senses. For instance, to judge the softness of our cats fur, we do not only look at it, we also run our fingers in idiosyncratic ways through its coat. Recently, we have shown that haptically perceived softness covaries with the compliance, viscosity, granularity, and furriness of materials (Dovencioglu et al.,2020). However, it is unknown whether vision can provide similar information about the various aspects of perceived softness. Here, we investigated this question in an experiment with three conditions: in the haptic condition, blindfolded participants explored materials with their hands, in the visual-static condition participants were presented with close-up photographs of the same materials, and in the visual-dynamic condition participants watched videos of the hand-material interactions that were recorded in the haptic condition. After haptically or visually exploring the materials participants rated them on various attributes. Our results show a high overall perceptual correspondence between the three experimental conditions. With a few exceptions, this correspondence tended to be strongest between haptic and visual-dynamic conditions. These results are discussed with respect to information potentially available through the senses, or through prior experience, when judging the softness of materials.

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bioRxiv2020

Dynamic dot displays reveal material motion network in the human brain

There is growing research interest in the neural mechanisms underlying the recognition of material categories and properties. This research field, however, is relatively more recent and limited compared to investigations of the neural mechanisms underlying object and scene category recognition. Motion is particularly important for the perception of non-rigid materials, but the neural basis of non-rigid material motion remains unexplored. Using fMRI, we investigated which brain regions respond preferentially to material motion versus other types of motion. We introduce a new database of stimuli - dynamic dot materials - that are animations of moving dots that induce vivid percepts of various materials in motion, e.g. flapping cloth, liquid waves, wobbling jelly. Control stimuli were scrambled versions of these same animations and rigid three-dimensional rotating dots. Results showed that isolating material motion properties with dynamic dots (in contrast with other kinds of motion) activates a network of cortical regions in both ventral and dorsal visual pathways, including areas normally associated with the processing of surface properties and shape, and extending to somatosensory and premotor cortices. We suggest that such a widespread preference for material motion is due to strong associations between stimulus properties. For example viewing dots moving in a specific pattern not only elicits percepts of material motion; one perceives a flexible, non-rigid shape, identifies the object as a cloth flapping in the wind, infers the objects weight under gravity, and anticipates how it would feel to reach out and touch the material. These results are a first important step in mapping out the cortical architecture and dynamics in material-related motion processing.

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bioRxiv2020

Assessing Topographic Structural Connectivity of the Human Basal Ganglia and Thalamus

The basal ganglia and thalamus play an important role in cognition, procedural learning, eye movements, control of voluntary motor movements, emotional control, habit development, and are structures that are severely impacted by neurological disorders such as Parkinsons disease, or Tourette syndrome. To understand the structural connectivity of cortical and subcortical circuits in the healthy human brain could thus be of pivotal importance for detecting changes in this circuitry and to start early intervention, to assess the progress of movement rehabilitation, or the effectiveness of therapeutic approaches in neuropsychiatry. While conventional clinical magnetic resonance imaging (MRI) is able to provide detailed information about connectivity at the macro level, the sensitivity and specificity of such structural imaging methods put limits on the amount of detail one can obtain when measuring in vivo connectivity of human basal ganglia and thalamus at routine clinical magnetic field strengths. In contrast, the multiband diffusion echo planar imaging method, which acquires multiple slices simultaneously, enables high resolution imaging of these abovementioned brain structures with only short acquisition times at 3-Tesla and higher magnetic field strengths. To unleash the greater potential of information embedded in data acquired with this technique, complementary data processing pipelines are required. Here, we use a protocol composed of multiband diffusion-, T1- and susceptibility weighted data acquisition sequences and introduce an associated pipeline based on combined manual and automated processing. The design of this data processing pipeline allows us to generate comprehensive in vivo participant-specific probabilistic patterns and visualizations of the structural connections that exist within basal ganglia and thalamic nuclei. Moreover, we are able to map specific parcellations of these nuclei into sub-territories based on their connectivity with primary motor-, and somatosensory cortex. This data processing strategy enables detailed subcortical structural connectivity mapping which could benefit early intervention and therapy methods for human movement rehabilitation and for treating neuropsychiatric disorders.

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bioRxiv2020

Material category determined by specular reflection structure mediates the processing of image features for perceived gloss

Recognising materials and their properties from visual information is vital for successful interactions with our environment, from avoiding slippery floors to handling fragile objects. Yet there is no simple mapping of retinal image intensities to the physical properties that define materials. While studies have investigated how material properties like surface gloss are perceived from regularities in image structure, such as the size, sharpness, contrast, and position of bright patches caused by specular reflections, little is known how this translates to the recognition of different material classes like plastic, pearl, satin, or steel, and the underlying mechanisms involved. We investigated this by collecting human psychophysical judgments about complex glossy objects rendered in natural illumination fields. We found that variations in specular image structure - produced either by different reflectance properties or direct manipulation of image features - caused categorical shifts in material appearance, suggesting that specular reflections provide diagnostic information about a wide range of material classes, including many that should be defined by more complex scattering functions. Moreover, differences in material category were predicted by, but also appeared to mediate, cues for surface gloss, providing evidence against a traditional feedforward view of neural processing that assumes combinations of mid-level properties mediate our holistic, categorical impressions. Instead, our results suggest that the image structure that triggers our perception of surface gloss plays a direct role in visual categorisation and, importantly, that the perception and neural processing of stimulus properties should not be studied in isolation but rather in the context of recognition.

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bioRxiv2019

The color appearance of three-dimensional, curved, transparent objects

Studies on the perceived color of transparent objects have elucidated potential mechanisms but have mainly focused on flat filters that overlay a flat background. However, studies with flat filters have not captured all aspects of physical transparency, such as caustics, specular reflections/highlights, and shadows. Here, we investigate color matching experiments with three-dimensional transparent objects for different matching stimuli: a uniform patch and a flat filter overlaying a variegated background. Two different instructions were given to observers: change the color of the matching stimulus until it has the same color as the transparent object (for the patch and flat filter) or until it has the same color as the dye that was used to tint the transparent object (for the patch). Regardless of instruction or matching element, observers match the mean chromaticity of the glass object, but the luminance of matches depends on the backgrounds of the test image and the matching element, indicating that a color constancy-esque discounting operation is at work. We applied three models from flat filter studies to see if they generalize to our stimuli: the convergence model and the ratio of either the means (RMC) or standard deviations (RSD) of cone excitations. The convergence model does not generalize to our stimuli, but the RMC generalizes to a wider range of stimuli than the RSD. However, there is an edge case where RMC also breaks down and there may be additional features that trade-off with RMC when observers match the color of thick, curved transparent objects.

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bioRxiv2019

Visual perception of surprising materials in dynamic scenes

Many objects that we encounter have typical material qualities: spoons are hard, pillows are soft, and jell-O dessert is wobbly. Over a lifetime of experiences, strong associations between an object and its typical material properties may be formed, and these associations not only include how glossy, rough or pink an object is, but also how it behaves under force: we expect knocked over vases to shatter, popped bike tires to deflate, and gooey grilled cheese to hang between two slices of bread when pulled apart. Here we ask how such rich visual priors affect the visual perception of material qualities and present a particularly striking example of expectation violation. In a cue conflict design, we pair computer-rendered familiar objects with surprising material behaviors (a linen curtain shattering, a porcelain teacup wrinkling, etc.) and find that material qualities are not solely estimated from the objects kinematics (i.e. its physical (atypical) motion while shattering, wrinkling, wobbling etc.); rather, material appearance is sometimes "pulled" towards the "native" motion, shape, and optical properties that are associated with this object. Our results, in addition to patterns we find in response time data, suggest that visual priors about materials can set up high-level expectations about complex future states of an object and show how these priors modulate material appearance.

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