The structure of frontoparallel haptic space is task dependent

In three experiments, we investigated the structure of frontoparallel haptic space. In the first experiment, we asked blindfolded participants to rotate a matching bar so that it felt parallel to the reference bar, the bars could be at various positions in the frontoparallel plane. Large systematic errors were observed, in which orientations that were perceived to be parallel were not physically parallel. In two subsequent experiments, we investigated the origin of these errors. In Experiment 2, we asked participants to verbally report the orientation of haptically presented bars. In this task, participants made errors that were considerably smaller than those made in Experiment 1. In Experiment 3, we asked participants to set bars in a verbally instructed orientation, and they also made errors significantly smaller than those observed in Experiment 1. The data suggest that the errors in the matching task originate from the transfer of the reference orientation to the matching-bar position

Haptic curvature contrast in raised lines and solid shapes

It is known that our senses are influenced by contrast effects and aftereffects. For haptic perception, the curvature aftereffect has been studied in depth but little is known about curvature contrast. In this study we let observers explore two shapes simultaneously. The shape felt by the index finger could either be flat or convexly curved. The curvature at the thumb was varied to quantify the curvature of a subjectively flat shape. We found that when the index finger was presented with a convex shape, a flat shape at the thumb was also perceived to be convex. The effect is rather strong, on average 20% of the contrasting curvature. The contrast effect was present for both raised line stimuli and solid shapes. Movement measurements revealed that the curvature of the path taken by the metacarpus (part of the hand that connects the fingers) was approximately the average of the path curvatures taken by the thumb and index finger. A failure to correct for the movement of the hand could explain the contrast effect

Про Iвана Франка в Академії адвокатури України

13 жовтня ц. р. в Академії адвокатури України (Київ) відбулася наукова конференція “Феномен Iвана Франка в духовній скарбниці України”, присвячена 150-річчю від дня народження письменника. У конференції взяли участь викладачі з різних вищих навчальних закладів України, наукові співробітники Iнституту літератури імені Т.Г.Шевченка Національної академії наук України, Національного музею літератури України, а також учителі ліцеїв, гімназій

Verdrängung widerständiger Lesarten? : Medien und Macht bei Jean Baudrillard und Stuart Hall

Die Arbeit behandelt einen Vergleich der Medientheorien Jean Baudrillards und Stuart Halls. Im Fokus steht die Frage nach der ‚Macht der Medien’: Versteht man Massenmedien als wichtigen Integrationsfaktor pluralistischer Gesellschaften – sie geben einen Orientierungsrahmen ‚relevanten’ Wissens an –, so sind sie gleichzeitig auch Machtfaktoren. Als radikal-apokalyptischer Theoretiker einer von medialen ‚Simulationen’ durchdrungenen Welt, sah Jean Baudrillard durch Massenmedien eine allumfassende gesellschaftliche Kontrolle eingerichtet. Aus Sicht der Cultural Studies, für deren Beschäftigung mit den Medien Stuart Hall wegweisend war und ist, treffen Medieninhalte auf ein Publikum, das immer schon über Erfahrungen, Wissen und Prägungen verfügt und daraus seine Präferenzen im Mediengebrauch ableitet – und auch entsprechende Kompetenzen ausbildet. Die Verbindung von Medien und Macht geschieht anhand des von Michel Foucault aufgestellten Modells des ‚Dipositivs’, das von Johanna Dorer für die Analyse öffentlicher Kommunikation fruchtbar gemacht worden ist. Der Blick wird hier auch auf das Internet gerichtet, durch dessen Verbreitung sich die Kommunikationslandschaft grundlegend gewandelt hat

Comparison of the haptic and visual deviations in a parallelity task

Deviations in both haptic and visual spatial experiments are thought to be caused by a biasing influence of an egocentric reference frame. The strength of this influence is strongly participant-dependent. By using a parallelity test, it is studied whether this strength is modality-independent. In both haptic and visual conditions, large, systematic and participant-dependent deviations were found. However, although the correlation between the haptic and visual deviations was significant, the explained variance due to a common factor was only 20%. Therefore, the degree to which a participant is “egocentric” depends on modality and possibly even more generally, on experimental condition

Keep an eye on your hands: on the role of visual mechanisms in processing of haptic space

The present paper reviews research on a haptic orientation processing. Central is a task in which a test bar has to be set parallel to a reference bar at another location. Introducing a delay between inspecting the reference bar and setting the test bar leads to a surprising improvement. Moreover, offering visual background information also elevates performance. Interestingly, (congenitally) blind individuals do not or to a weaker extent show the improvement with time, while in parallel to this, they appear to benefit less from spatial imagery processing. Together this strongly points to an important role for visual processing mechanisms in the perception of haptic inputs

The Influence of Aging on Perceptual Grouping in Haptic Search

Perceptual grouping speeds up haptic search. This has particularly been shown for grouping of distractors by similarity and good continuation [1]. Here, we investigated the effect of aging on grouping in haptic search. We reasoned that because older adults have less cognitive resources available for processing perceptual information, they would benefit more from grouping as compared to younger adults. We tested this hypothesis in a haptic search task in which proximity, similarity and good continuation of the distractors were manipulated. We found that older adults indeed show a larger effect of distractor similarity on search times as compared to younger adults, where similar dis- tractors were processed faster than dissimilar distractors. However, older adults showed an opposite effect of grouping by proximity, where items that were further apart were processed faster. This may be caused by a strong bowed spatial position effect in older adults: stimuli that are closer to each other are more difficult to discriminate. We conclude that haptic perceptual grouping by similarity has larger benefits in elderly as compared to younger adults

Using curvature information in haptic shape perception of 3D objects

Are humans able to perceive the circularity of a cylinder that is grasped by the hand? This study presents the findings of an experiment in which cylinders with a circular cross-section had to be distinguished from cylinders with an elliptical cross-section. For comparison, the ability to distinguish a square cuboid from a rectangular cuboid was also investigated. Both elliptical and rectangular shapes can be characterized by the aspect ratio, but elliptical shapes also contain curvature information. We found that an elliptical shape with an aspect ratio of only 1.03 could be distinguished from a circular shape both in static and dynamic touch. However, for a rectangular shape, the aspect ratio needed to be about 1.11 for dynamic touch and 1.15 for static touch in order to be discernible from a square shape. We conclude that curvature information can be employed in a reliable and efficient manner in the perception of 3D shapes by touch

Grabbing subitizing with both hands: bimanual number processing

Visual judgment of small numerosities (<4) is generally assumed to be done through subitizing, which is a faster process than counting. Subitizing has also been shown to occur in haptic judgment of the number of spheres in the hand. Furthermore, interactions have been shown to exist between visually perceived numbers and hand motor action. In this study, we compare enumeration of a set of spheres presented to one hand (unimanual) and enumeration of the same total number of spheres presented divided over the two hands (bimanual). Our results show that, like in vision, a combination of subitizing and counting is used to process numbers in active touch. This shows that numbers are processed in a modality-independent way. This suggests that there are not only interactions between perception of numbers and hand motor action, but rather that number representation is modality-independent