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The ability of 26 younger (mean age was 22.5 years) and older adults (mean age was 72.6 years) to haptically perceive material properties was evaluated. The participants manually explored (for 5 seconds) 42 surfaces twice and placed each of these 84 experimental stimuli into one of seven categories: paper, plastic, metal, wood, stone, fabric, and fur/leather. In general, the participants were best able to identify fur/leather and wood materials; in contrast, recognition performance was worst for stone and paper. Despite similar overall patterns of performance for younger and older participants, the younger adults' recognition accuracies were 26.5% higher. The participants' tactile acuities (assessed by tactile grating orientation discrimination) affected their ability to identify surface material. In particular, the Pearson r correlation coefficient relating the participants' grating orientation thresholds and their material identification performance was -0.8: The higher the participants' thresholds, the lower the material recognition ability. While older adults are able to effectively perceive the solid shape of environmental objects using the sense of touch, their ability to perceive surface materials is significantly compromised.

Does recognizing the transformations that gave rise to an object's retinal image contribute to early object recognition? It might, because finding a partially occluded object among similar objects that are not occluded is more difficult than finding an object that has the same retinal image shape without evident occlusion. If this is because the occlusion is recognized as such, we might see something similar for other transformations. We confirmed that it is difficult to find a cookie with a section missing when this was the result of occlusion. It is not more difficult to find a cookie from which a piece has been bitten off than to find one that was baked in a similar shape. On the contrary, the bite marks help detect the bitten cookie. Thus, biting off a part of a cookie has very different effects on visual search than occluding part of it. These findings do not support the idea that observers rapidly and automatically compensate for the ways in which objects' shapes are transformed to give rise to the objects' retinal images. They are easy to explain in terms of detecting characteristic features in the retinal image that such transformations may hide or create. [ABSTRACT FROM AUTHOR]

Subjective contours are widely considered to be an aspect of the perception of occlusion, but considerations of occlusion do not always drive predictions of their strength. Occluding surfaces have no necessary relationship to the contours they occlude, yet it is commonly predicted that subjective contours will be strongest for inducer alignments that are orthogonal to inducer orientations. In several papers we have proposed that a lack of relationship between inducers and their alignment promotes seeing subjective contours. We explore this further here using horizontal or near-horizontal thin-line inducers arranged vertically with linearly aligned terminations along central gaps. Subjective contour strength was measured using the method of paired comparison in two experiments. The weakest subjective contours were found when the gap was orthogonal to the inducers and parallel to the outer edges of the line set. Subjective contours were strengthened by orientation contrast, defined either as a nonorthogonal relationship between the gap and the inducers or as nonparallelism between the gap and the outer alignments of the inducers. The effect was replicated at both high and low line densities. We also confirmed a strong effect of high inducer entropy (variations in inducer orientation and separation) with thin-line inducers. The results support the view that the lack of a relationship of alignments to what is aligned is a major determinant of subjective contour strength.

In typical figure-ground displays the figure has shape and is perceived as being in front, whereas the ground is shapeless and recedes to the back. The recent literature on the visual perception of holes has questioned the nature of this coupling between shape and depth both theoretically and empirically. In this paper we provide a theoretical framework that clarifies the underlying issues and we report new evidence supporting the view that the shape of a hole is perceived as the shape of its interior region. Palmer, Davis, Nelson, and Rock (2008 Perception, 37, 1569-1586) showed that the shape of the interior region of a hole is remembered as such, even though the surface visible through it is perceived as farther in depth. The present paper extends this evidence to perceiving holes. Participants performed a speeded shape-matching task in which they compared a surrounded interior region (of either a hole or an object) or its exterior complement with one of several shapes. The results indicate that holes are perceived as shaped in the same way as their material counterparts. We conclude that the shape of a hole is encoded as the shape of its interior region, even though that region contains no surface material. These results can be reconciled with recent experiments that have provided evidence that holes are perceived differently from their material counterparts.

Harman et al (1999, Current Biology 9 1315-1318) showed that active exploration of novel objects allows faster recognition of these objects than passive viewing. Here, we examined whether active exploration of particular objects can facilitate subsequent view matching of different objects within the same category. In the generalisation phase, participants performed a matching task between two serially presented views of novel paper-clip objects. When the two views were of the same object, these were related by rotation about the vertical or horizontal axis. Subsequently, in the observation phase, participants were presented with another 5 paper-clip objects. One group of participants (active group) actively explored each of the objects for 20 s using a trackball over a limited range (-45 degrees to +45 degrees) of the horizontal axis. The other participants observed a replay of the active exploration of each of these objects by a participant in the active group (passive group) or observed a static view of the objects (still group). Following this observation phase, the generalisation phase was repeated twice for all groups of participants. The active group showed a clear expansion of the generalisation range about the horizontal axis. However, this expansion disappeared when we replicated the experiment using a smaller range of active exploration (-30 degrees to +30 degrees) and the experiment in which the participants observed a rotating object within the range of -45 degrees to +45 degrees. Furthermore, we found a significant improvement in view generalisation about the vertical axis when participants actively explored objects using a turntable over a range in -45 degrees to +45 degrees of the vertical axis. Most importantly, since participants explored different objects from the ones that were used in the generalisation phase, these results cannot be explained by improvement of the encoding process. The present findings therefore suggest that: (i) active exploration facilitates the process of view matching, (ii) this effect depends on the exploration range and rotational axis, and (iii) interaction between motor and visual information is necessary to facilitate the process of view matching.

We analyse here people's perception of their reflections in mirrors placed in different positions. In two experiments, participants looked at their mirror image, in a third experiment they looked at another person's image. In both cases they were asked to answer a series of questions about how the virtual body appeared relative to the real body, focusing on different aspects. In experiment 1, they were asked to decide whether the reflections were identical, similar, different, or opposite in terms of the global relationship, orientation, and lateralisation (left right arm). In experiment 2 they were instructed to make simple gestures and to evaluate if the gestures in the reflection were identical, opposite, similar, or different from theirs. Results show that 'identity' was preferred when the mirror was in front, and 'opposition' was preferred when the mirror was below. When opposition was experienced, it was attributed mainly to the exocentric frame of reference. Egocentric left-right reversal was not a common experience, although it was reported more frequently when the mirror was in front. The different roles of the exocentric and egocentric frames of reference were further tested in experiment 3, in which the condition of an observer looking at another person's reflection was studied. Contrary to the emphasis on the egocentric frame of reference in the literature on the 'mirror question', results presented in this paper demonstrate the importance of the exocentric frame of reference in influencing how observers react to their reflections.

The Hermann grid illusion consists of smudges perceived at the intersections of a white grid presented on a black background. In 1960 the effect was first explained by a theory advanced by Baumgartner suggesting the illusory effect is due to differences in the discharge characteristics of retinal ganglion cells when their receptive fields fall along the intersections versus when they fall along non-intersecting regions of the grid. Since then, others have claimed that this theory might not be adequate, suggesting that a model based on cortical mechanisms is necessary [Lingelbach et al, 1985 Perception 14(1) A7; Spillmann, 1994 Perception 23 691 708; Geier et al, 2004 Perception 33 Supplement, 53; Westheimer, 2004 Vision Research 44 2457 2465]. We present in this paper the following evidence to show that the retinal ganglion cell theory is untenable: (i) varying the makeup of the grid in a manner that does not materially affect the putative differential responses of the ganglion cells can reduce or eliminate the illusory effect; (ii) varying the grid such as to affect the putative differential responses of the ganglion cells does not eliminate the illusory effect; and (iii) the actual spatial layout of the retinal ganglion cell receptive fields is other than that assumed by the theory. To account for the Hermann grid illusion we propose an alternative theory according to which the illusory effect is brought about by the manner in which S1 type simple cells (as defined by Schiller et al, 1976 Journal of Neurophysiology 39 1320-1333) in primary visual cortex respond to the grid. This theory adequately handles many of the facts delineated in this paper.

In this paper we investigate the role of contours and junctions in the perception of single-plane achromatic transparency. In order to measure the accuracy with which observers encode transparency, a six-luminance stimulus was employed in which the figural properties could be easily manipulated. Accuracy was measured by requiring subjects to select (either by the method of adjustment or by using a forced-choice procedure) the luminance that best completed a simulated transparent filter. The X junctions in the stimulus were destroyed or perturbed in three experiments. Simple occlusion of the junction (experiment 1), and perturbation of the orientation of the contours of the filter as they pass through the junction (experiment 3) resulted in small but significant reductions in performance. On the other hand, a sudden change in orientation of the background (material) contours (experiment 2) resulted in a small but significant enhancement of overall performance compared with the control stimulus. In the forced-choice task, reversals in the polarity of contours (as defined by the brightness order of flanking regions) around the junction were shown to effect large changes in subjects' accuracy in processing transparency. The overall results show that X and Psi junctions are indeed salient properties of transparent stimuli. The findings suggest that jagged contours with sudden changes in direction are more likely to be attributed to reflectance (material) changes than to changes due to a transparent filter (or to illumination).

Rock [1973, Orientation and Form (New York: Academic Press)] showed that form perception generally depends more on the orientation of a stimulus in world coordinates than on its orientation in retinal coordinates. He suggested that the assignment of an object's 'environmental orientation' depends on gravity, visual frame of reference, and the observer's ability to impose orientation along one axis or another. This paper shows that the assignment of environmental orientation and perceived 3-D form also depends on the relationship between an object and retinally adjacent surfaces in the scene to which it might be attached. Whereas previous examples have demonstrated effects of orientation on 2-D form, we show that orientation can affect the perceived intrinsic 3-D shape of a volume.

We apply the 'patchwork engine' (PE; van Tonder and Ejima, 2000 Neural Networks forthcoming) to encode spaces between textons in an attempt to find a suitable feature representation of anti-textons [Williams and Julesz, 1991, in Neural Networks for Perception volume 1: Human and Machine Perception Ed. H Wechsler (San Diego, CA: Academic Press); 1992, Proceedings of the National Academy of Sciences of the USA 89 6531-6534]. With computed anti-textons it is possible to show that tessellation and distribution of anti-textons can differ from that of textons depending on the ratio of texton size to anti-texton size. From this we hypothesise that variability of anti-textons can enhance texture segregation, and test our hypothesis in two psychophysical experiments. Texture segregation asymmetry is the topic of the first test. We found that targets on backgrounds with regular anti-textons segregate more strongly than on backgrounds with highly variable anti-textons. This neatly complements other explanations for texture segregation asymmetry (e.g. Rubenstein and Sagi, 1990 Journal of the Optical Society of America A 7 1632-1643). Second the relative significance of textons and anti-textons in human texture segregation is investigated for a limited set of texture patterns. Subjects consistently judged a combination of texton and anti-texton gradients as more conspicuous than texton-only gradients, and judged texton-only gradients as being more conspicuous than anti-texton-only gradients. In the absence of strong texton gradients the regularity versus irregularity of anti-textons agrees with perceived texture segregation. Using PE outputs as anti-texton features thus enabled the conception of various useful tests on texture segregation. The PE is originally intended as a general image segmentation method based on symmetry axes. With this paper we therefore hope to relate anti-textons with visual processing in a wider sense.

The purpose of this paper is to offer demonstrations of 'illusory volumes' in the spirit of the illusory flat surfaces described by Kanizsa. These demonstrations of illusory volumes exploit a new cue to the recovery of surface curvature from ambiguous images: conformation. In assuming conformation, the visual system assumes that the surface of a volume conforms to the curvature of its neighboring, underlying, or supporting surface, in the absence of image cues to the contrary. Demonstrations that exploit the assumption of conformation provide several insights into the nature of the inferential processing that underlies contour, surface, and volume formation. In particular, these demonstrations imply that the visual system does not calculate local surface curvature, illusory contours, or occlusion relationships before it analyzes global surface relationships.

How does the visual system recognise stimuli presented at different orientations? According to the multiple-views hypothesis, misoriented objects are matched to one of several orientation-specific representations of the same objects stored in long-term memory. Much of the evidence for this hypothesis comes from the observation of group mean orientation effects in recognition memory tasks showing that the time taken to identify objects increases as a function of the angular distance between the orientation of the stimulus and its nearest familiar orientation The aim in this paper is to examine the validity of this interpretation of group mean orientation effects. In particular, it is argued that analyses based on group performance averages that appear consistent with the multiple-views hypothesis may, under certain circumstances, obscure a different theoretically relevant underlying pattern of results. This problem is examined by using hypothetical data and through the detailed analysis of the results from an experiment based on a recognition memory task used in several previous studies. Although a pattern of results that is consistent with the multiple-views hypothesis was observed in both the group mean performance and the underlying data, it is argued that the potential limitations of analyses based solely on group performance averages must be considered in future studies that use orientation effects to make inferences about the kinds of shape representations that mediate visual recognition.

Adult subjects drew the visual projection of two models. One model was a trapezoid placed in the frontoparallel plane. The other was a tilted rectangle which displayed the same projective shape on a frontoparallel plane as the trapezoid. The drawing conditions were varied in two ways: the model remained available for inspection during the drawing task or it was masked after initial inspection; the subjects drew on paper placed flat on the table or on a vertical glass pane placed in front of the model (ie on a da Vinci window). The results were that (i) the projective shape of the frontoparallel trapezoid was reproduced accurately whereas that of the tilted rectangle was systemically distorted in the direction of its actual physical dimensions; (ii) when subjects drew on paper, the presence or absence of a view of the model made no difference to the amount of distortion; (iii) drawing on a da Vinci window improved accuracy even when the model was hidden. These findings provide information about the relative roles of object-centred knowledge, perceptual abilities, and depiction skills in drawing performance.

A study is reported of the depth relief in a simple three-dimensional scene consisting of a white, rough sphere on a planar support, illuminated in a natural manner. Viewing conditions included monocular and binocular as well as 'synoptical' viewing. In the synoptical condition the eyes are optically superimposed. The local surface attitude was probed via a gauge figure that had to appear as a circle painted upon the surface of the object. The measurements allow a reconstruction of the depth relief, which can be compared with the (known) range map. Idiosyncratic differences between three subjects were found that are the exact reverse of what was found for these same subjects for the case of pictorial relief reported in an earlier paper. Apparently the subjects put different weights on sources of sometimes conflicting, sometimes corroborative evidence. The relief is deepest for binocular vision, flatter for monocular vision, and flatter still for synoptical vision. Deviations from veridicality that cannot be explained by mere depth scaling exist and may be due to the nature of the monocular cues.

Perceptual organisation, and especially the computation of contour information, has been the object of considerable interest in the last few years. In the first part of the paper we review recent accounts on the mechanisms involved in the processing of contour. In the second part we report an experiment designed to examine (1) how physical parameters such as spatial proximity and collinearity of elements affect the integration of global contour in objects and (2) whether the activation of stored representations of objects facilitates the computation of contour. Incomplete forms varying in the spacing and the alignment of line segments on their contour were used as stimuli in a matching task. Subjects were asked to decide which of two laterally displayed figures matched a reference form presented previously. The matching target and the distractor were physically identical but differed in their orientation. In one condition the reference object was always an outline drawing of an object. In a second condition the reference object was either a complete object or a more or less identifiable incomplete form. Little variation in performance was found for forms having continuous and discontinuous contour up to a spacing of 5 pixels (10.8 min) between elements. Response times and errors increased abruptly beyond this limit. This effect occurred in the two conditions of reference stimulus, suggesting that the computation of contour information is more affected by physical constraints at early processes than by high-level processes involving activation of stored structural representations of objects.

Young et al (1987) have demonstrated that the juxtaposition of top and bottom halves of different faces produces a powerful impression of a novel face. It is difficult to isolate perceptually either half of the 'new' face. Inversion of the stimulus, however, makes this task easier. Upright chimeric faces appear to evoke strong and automatic configurational processing mechanisms which interfere with selective piecemeal processing. In this paper three experiments are described in which a matching paradigm was used to show that Young et al's findings apply to unfamiliar as well as to familiar faces. The results highlight the way in which minor procedural differences may alter the way in which subjects perform face-recognition tasks.

Three experiments on the perception of simple four-sided two-dimensional shapes are reported. In the first experiment subjects were given a paper-and-pencil test in which they had to consider each of a set of shapes in turn. They were instructed to draw in what they considered to be the most salient axis of each of the shapes ie a line that they felt most naturally went with the shape. The results showed a significant tendency to draw an axis of symmetry if one was present. However, when presented with instances of a shape that was elongated but possessed no symmetries they failed to consistently draw any particular axis. A further, speeded classification, task revealed that for this shape explicit axis information appeared not to influence performance. In contrast, such information clearly affected performance with a shape that did possess a salient axis of symmetry and elongation. Indeed this axis was shown to be integral with the contour of the shape when a final classification experiment was carried out. The axis of elongation of the other shape acted as a characteristic which was separable from the contour. The results are discussed in relation to accounts of shape perception which assume that a necessary stage in the perception of shape is the derivation of an axis-based structural description.

Defensive responses to looming visual stimuli have been obtained in a wide variety of species, including human infants as young as one week. This phenomenon has not, however, been formally demonstrated for adults under laboratory conditions. In this paper it is reported that similar responses, namely avoidance movements of the head, can be obtained in most human adults provided that they are suitably distracted by playing a computer tracking game. Such behaviours were not obtained when subjects were not so distracted. The use of control conditions also ruled out the possibility that simple movement cues from stimuli presented on a noncollision trajectory are sufficient stimulus to obtain defensive responses. It is of interest to note that latencies for avoidance movements were significantly shorter than those for orienting movements in the same situation, but were no different from the latencies for orienting movements when subjects were not distracted. It is argued that these findings are consistent with the proposition that defensive head movements to looming stimuli, like orienting movements to novel peripheral stimuli, represent a basic visual competence that is normally suppressed (or subsumed) by higher competences. The decision to avoid is probably based on the computation of time to contact, and may reflect the operation of a subcortical system for elementary analysis of optic flow.

A Google search lets you quickly compare various dictionary meanings. Indeed, the terms Umwelt and Innenwelt derive from the work of Jakob von Uexküll ([14], [15]), a biologist who did his major work in the first half of the 20th century. The "New Loop" (yes, there was an "old loop", it would currently be called a "perception-action cycle") drives the semiotic meaning making in Jakob von Uexküll's thinking. Von Uexküll felt he had constructed a biological model of Kant's ([6]) philosophy (the Ding an sich, von Uexküll speaks of " Merkmalsträger "). [Extracted from the article]

Evidence is presented that two distinct effects are generated when a sine-wave grating is temporally modulated. These effects may differentiated on the grounds of different responses with different forms of temporal modulation (drift or phase reversal), different behaviour with changes of visual eccentricity and with changes of contrast. One effect is roughly equivalent to spatial-frequency doubling, as described by Kelly. The other is seen as a fractional increase in apparent spatial frequency ie 1.2 X 1.4 X the original. Earlier papers are reviewed to lend support to these conclusions. The results obtained for spatial-frequency doubling are consistent with Kelly's model of a nonlinearity followed by a temporal integration. Spatial-frequency doubling emerges under conditions where a fractional increase in apparent spatial frequency would generally be expected but the particular spatiotemporal conditions are such that a breakdown in the motion-correspondence process may be suspected. Reasons for the existence of fractional shifts are not entirely clear, but it is argued that the similarity of the shifts induced by various manipulations (decreases of luminance, decreases of contrast, temporal modulation) are such that a general explanation must be sought, rather than one specific to temporal modulation alone.

In general, a picture can represent a specific environment of scene only when the picture is seen from a unique viewing point. The determination of this unique point and of the distortions that occur when the picture is viewed from other points is crucial to all aspects of pictorial perception. To clarify the effects of the point of observation on pictorial space, the present paper discusses how the correct point may be calculated, provides a geometric analysis of the effects of altering the viewing point, and briefly reviews the effects of such alterations on space perception.

In this paper, a revised Pandemonium-like model of visual-feature processing is formulated and a preliminary test of its feasibility is reported. The model differentiates visual-feature processing into a series of hierarchical stages organized by increasing complexity, with the output of each stage going both to the next higher stage, and directly to a more central processor. In the experiment, subjects sorted decks of cards into piles according to the presence or absence of a target stimulus which differed from nontargets in a variety of different features; detection of a feature was sufficient for detection of a target. The data generally supported the revised Pandemonium model, in that targets which differed from nontargets in features thought to be low in the hierarchy were processed faster than targets whose difference was in a high level feature. An extension of the revised model did somewhat less well in predicting the results of sorting for targets in which detection of any one of several features was sufficient for target detection.

It has previously been reported by Smets that there is an increase in the magnitude of the monocular oblique effect when a 70 dB(A), 1 kHz acoustic stimulus is presented contralaterally, but not ipsilaterally, to the viewing eye. This finding was interpreted as one which provided difficulties both for data-driven models of information processing and for the cortical simple cell explanation of the oblique effect. There are several logical and methodological difficulties in Smets's paper, and in the two experiments reported here the effect found by Smets was not replicated. The failure to observe the effect was robust under conditions that maximised the possibility of neural interaction. It is concluded that acoustic stimulation does not affect the magnitude of the oblique effect.

It is well-known that patterns of eccentric circles when slowly rotated give rise to compelling three-dimensional impressions of cones or conical holes which can 'wobble' as the pattern rotates. The wobble can be considered as part of the overall phenomenon of depth elicited from a rotating display, the 'stereokinetic' effect (SKE). This paper considers the three-dimensional appearance as being the result of the sliding of contours and thus it imitates the motion parallax found in real three-dimensional objects in motion. New variants of SK figures are used to examine these points. An analogy with computer programs is proposed which questions earlier views on the location of perceptual invariance.

Starting from a study of the Penrose triangle, the theory is advanced that our perception of the relative spatial positions of parts of a figure is mediated by a set of significant directions (or axes). Illustration and exploration of the theory in this paper revolves around examples drawn mostly from a family of figures related to the Penrose triangle. This family is defined partly in terms of the common nature of its members' anomalies, and partly by the feature that they are seen as configurations of 'beams'. This feature and the conditions for it are also examined by the use of examples.

One group of subjects rated differences in brightness and another the clarity of illusory contours for eight figure-ground combinations of the Kanizsa and Ehrenstein patterns made from Munsell papers. For four combinations there was a difference in Munsell value (brightness) between figure and ground and for another four no difference. For the latter the pattern was derived from differences in hue or colour quality. For the combinations with a Munsell value difference the ratings of both brightness difference and contour clarity were high and for those of uniform value both were low. The results are interpreted as supporting the argument that illusory contours derive primarily from contrast-induced differences in brightness and possibly in colour between contiguous, physically uniform regions.

Psychologists disagree about what is wrong with the fork. R L Gregory says that its spatial orientation is impossible. J M Kennedy claims that it lacks the intact boundaries characteristic of solid objects. In fact, the fork possesses both these flaws. It cannot be made out of wires because the rectangular/trapezoidal shapes representing its conjoined middle plate and prong create a self-contradictory angle between planes. Further, the fork cannot be cut from a flat sheet of paper because figural contours delineating its boundaries show us self-contradictory transformations of surfaces into air space. The fork is important because its two flaws form the bases of distinct classes into which all the recognized impossibles fall. Different arrangements of the fork's critical rectangle/trapezoid shapes are the sole source of paradox in 'depth impossibles'--for instance, the triangle and staircase drawings by R and L S Penrose, the window design published anonymously in Aviation Week & Space Technology in 1964, and Belvedere by M C Escher. And variations on the fork's self-contradictory boundary constitute the only source of paradox in 'impossible solids'--for instance, Escher's Day and Night, Victor Vasarely's Study in Axonometric Perspective, and Escher's Convex and Concave.

This paper examines the structure underlying textural patterns. To this end, aspects of a model for texture are developed on the basis of both perceptual processes of the observer and structural properteries of the patterns. Local constructs called primitives serve as generators for globally perfect, but unobservable, ideal textures. Study of the graph representation of these ideal textures reveals the basic regularity underlying visual textures. These perfect patterns are then transformed into observable textures by transformations which must not violate psychophysically based restrictions. Interpretively ambiguous textural patterns are used to demonstrate the influence that local primitives have on the formation of global pattern organizations.

A method for creating a variety of pseudo-random 'noisy' stimuli that possess several useful statistical and phenomenal features for psychophysical experimentation is outlined. These stimuli are derived from a pseudo-periodic function known as multidimensional noise. This class of function has the desirable property that it is periodic, defined on a fixed domain, is roughly symmetric, and is stochastic, yet consistent and repeatable. The stimuli that can be created from these functions have a controllable amount of complexity and self-similarity properties that are further useful when generating naturalistic looking objects and surfaces for investigation. The paper addresses the creation and manipulation of stimuli with the use of noise, including an overview of this particular implementation. Stimuli derived from these procedures have been used successfully in several shape and surface perception experiments and are presented here for use by others and further discussion as to their utility. [ABSTRACT FROM AUTHOR]

This article considers evidence, primarily drawn from art, that one kind of impossible colour, yellowish blue, can be experienced. [ABSTRACT FROM AUTHOR]