Christiane B. Wiebel

Bio: Christiane B. Wiebel is an academic researcher from University of Giessen. The author has contributed to research in topics: Haptic technology & Categorization. The author has an hindex of 7, co-authored 12 publications receiving 303 citations. Previous affiliations of Christiane B. Wiebel include Technical University of Berlin.

Perceptual qualities and material classes.

Abstract: Under typical viewing conditions, we can easily group materials into distinct classes (eg, woods, plastics, textiles) Additionally, we can also make many other judgments about material properties (eg, hardness, rigidity, colorfulness) Although these two types of judgment (classification and inferring material properties) have different requirements, they likely facilitate one another We conducted two experiments to investigate the interactions between material classification and judgments of material qualities in both the visual and semantic domains In Experiment 1, nine students viewed 130 images of materials from 10 different classes For each image, they rated nine subjective properties (glossiness, transparency, colorfulness, roughness, hardness, coldness, fragility, naturalness, prettiness) In Experiment 2, 65 subjects were given the verbal names of six material classes, which they rated in terms of 42 adjectives describing material qualities In both experiments, there was notable agreement between subjects, and a relatively small number of factors (weighted combinations of different qualities) were substantially independent of one another Despite the difficulty of classifying materials from images (Liu, Sharan, Adelson, & Rosenholtz, 2010), the different classes were well clustered in the feature space defined by the subjective ratings K-means clustering could correctly identify class membership for over 90% of the samples, based on the average ratings across subjects We also found a high degree of consistency between the two tasks, suggesting subjects access similar information about materials whether judging their qualities visually or from memory Together, these findings show that perceptual qualities are well defined, distinct, and systematically related to material class membership

Visual and haptic representations of material properties.

Abstract: Research on material perception has received an increasing amount of attention recently. Clearly, both the visual and the haptic sense play important roles in the perception of materials, yet it is still unclear how both senses compare in material perception tasks. Here, we set out to investigate the degree of correspondence between the visual and the haptic representations of different materials. We asked participants to both categorize and rate 84 different materials for several material properties. In the haptic case, participants were blindfolded and asked to assess the materials based on haptic exploration. In the visual condition, participants assessed the stimuli based on their visual impressions only. While categorization performance was less consistent in the haptic condition than in the visual one, ratings correlated highly between the visual and the haptic modality. PCA revealed that all material samples were similarly organized within the perceptual space in both modalities. Moreover, in both senses the first two principal components were dominated by hardness and roughness. These are two material features that are fundamental for the haptic sense. We conclude that although the haptic sense seems to be crucial for material perception, the information it can gather alone might not be quite fine-grained and rich enough for perfect material recognition.

The speed and accuracy of material recognition in natural images.

Abstract: We studied the time course of material categorization in natural images relative to superordinate and basic-level object categorization, using a backward-masking paradigm. We manipulated several low-level features of the images—including luminance, contrast, and color—to assess their potential contributions. The results showed that the speed of material categorization was roughly comparable to the speed of basic-level object categorization, but slower than that of superordinate object categorization. The performance seemed to be crucially mediated by low-level factors, with color leading to a solid increase in performance for material categorization. At longer presentation durations, material categorization was less accurate than both types of object categorization. Taken together, our results show that material categorization can be as fast as basic-level object categorization, but is less accurate.

The Oxford handbook of perceptual organization

Abstract: SECTION ONE: GENERAL BACKGROUND SECTION TWO: GROUPS, PATTERNS, TEXTURES SECTION THREE: CONTOURS AND SHAPES SECTION FOUR: FIGURE-GROUND ORGANIZATION SECTION FIVE: SURFACE AND COLOUR PERCEPTION SECTION SIX: MOTION AND EVENT PERCEPTION SECTION SEVEN: PERCEPTUAL ORGANIZATION AND OTHER MODALITIES SECTION EIGHT: SPECIAL INTEREST TOPICS SECTION NINE: APPLICATIONS OF PERCEPTUAL ORGANIZATION SECTION TEN: THEORETICAL APPROACHES

Accuracy and speed of material categorization in real-world images.

Abstract: It is easy to visually distinguish a ceramic knife from one made of steel, a leather jacket from one made of denim, and a plush toy from one made of plastic. Most studies of material appearance have focused on the estimation of specific material properties such as albedo or surface gloss, and as a consequence, almost nothing is known about how we recognize material categories like leather or plastic. We have studied judgments of high-level material categories with a diverse set of real-world photographs, and we have shown (Sharan, 2009) that observers can categorize materials reliably and quickly. Performance on our tasks cannot be explained by simple differences in color, surface shape, or texture. Nor can the results be explained by observers merely performing shape-based object recognition. Rather, we argue that fast and accurate material categorization is a distinct, basic ability of the visual system.