bluuebunny/crossref_metadata_2025 huggingface dataset:
Video transport over multi‐hop directional wireless networks
Authors: Li Yang , Man Hong
Published: January 2007

Exploiting directional antenna technology in wireless networks has become an attractive option for multimedia applications because of the potential capacity increase through spatial reuse. However, it has also been recognized that multi‐hop directional networks may suffer long transmission delays and frequent link breakages if conventional routing protocols (e.g., AODV and DSR) are used. This is mainly caused by ‘node deafness’ in directional transmission. To address this problem, we propose a multi‐path routing scheme which focuses more on minimizing per‐hop delays instead of traditional route length. In this paper, an analytical and numerical analysis of link breakages in multi‐hop directional network is presented, along with an introduction to our multi‐path routing scheme and two implementations based on AODV and DSR protocols. We further propose a differentiated service (DiffServ) framework for layered video transport over multi‐hop directional network using QoS aware multi‐path routing. Both network layer and application layer simulation results are presented to demonstrate the effectiveness of the proposed video transport scheme over directional networks. Copyright © 2007 John Wiley & Sons, Ltd.
Modelling farmer decision-making: concepts, progress and challenges
Authors: Edwards-Jones G.
Published: January 2007

Decisions made by farmers may have large influences beyond the farm boundary, and for this reason they are often of interest to Government and the public. The process of adoption of new technologies and policies has received considerable academic attention over many years, and this has highlighted the rôle of social influences in decision-making. In addition a range of purely economic-based models of farmer decision-making have been developed in order to predict potential changes in agriculture and land use under future policy and market scenarios. Since the 1990s these traditional approaches to understanding decision-making have been supplemented by an increasing input from psychology. As a result of this work it is clear that farmers' decisions are influenced by a range of factors which may be grouped under six headings: socio-demographics of the farmer, psychological make up of the farmer, the characteristics of the farm household, structure of the farm business, the wider social milieu and the characteristics of the innovation to be adopted. This paper presents a short review of the quantitative methods that seek to integrate insights from economics and social science within theoretical frameworks derived from psychology. Suggestions for further work include more empirical study in farmer decision-making related to animal health and welfare, the rôle of the farmers' own health status in decision-making and the formal integration of economic and psychological variables in simulation models.
The reopening of a collapsed fluid-filled elastic tube
Authors: JUEL ANNE , HEAP ALEXANDRA
Published: January 2007

We present an experimental study of the reopening mechanics of a collapsed liquid-filled elastic tube. The experiment is a simple mechanical model of pulmonary airway reopening and aims to assess the robustness of existing theoretical models. A metre-long horizontal elastic tube of inner radius Ri=4.88 ± 0.14mm is filled with silicone oil and is carefully collapsed mechanically. The injection of nitrogen at a constant flow rate results in the steady propagation of an air finger, after the decay of initial transients. This behaviour is observed over the realizable range of the capillary numbers Ca, which measures the ratio of viscous and capillary forces. With increasing Ca, the transition region between the collapsed and reopened sections of the tube shortens, and the height of the tube behind the bubble tip increases. We also find that air fingers can propagate in partially reopened tubes, in which the transmural pressure is negative far behind the finger tip.

The effect of viscosity on the reopening dynamics was explored by performing experiments using three different grades of silicone oil, with kinematic viscosities of 1000cS, 200cS and 100cS. A direct comparison between the experimental pressure dependence on Ca and numerical simulations of the zero-gravity three-dimensional airway-reopening model of Hazel & Heil (Trans. ASME: J. Biomech. Engng, vol. 128, 2006, p. 473) highlights some significant differences. Within the experimental parameter range, gravity profoundly influences the reopening mechanics in several ways. The reopening tube is supported by a rigid base, which induces an asymmetry about the horizontal mid-plane of the collapsed tube, resulting in distinct phases of reopening as Ca increases. In addition, buoyancy forces act on the air finger, which is observed to propagate near the top of the cross-section of the tube, leaving a thicker fluid-lining below. In the limit of small Ca, the height of the reopened tube increases significantly with viscosity. Experimental evidence suggests that this increase in viscosity leads to significant changes in the film configuration behind the propagating finger, caused by the increased contribution of buoyancy forces. The altered film configuration changes the mechanical load on the tube walls and, hence, the shape of the reopened tube.
Third-order structure function relations for quasi-geostrophic turbulence
Authors: LINDBORG ERIK
Published: January 2007

We derive two third-order structure function relations for quasi-geostrophic turbulence, one for the forward cascade of potential enstrophy and one for the inverse cascade of energy. These relations are the counterparts of Kolmovorov's (1941) four-fifths law for the third-order longitudinal structure functions of three-dimensional turbulence.
Inhibitory effect of BIBN4096BS, CGRP8–37, a CGRP antibody and an RNA‐Spiegelmer on CGRP induced vasodilatation in the perfused and non‐perfused rat middle cerebral artery
Authors: Edvinsson L , Nilsson E , Jansen‐Olesen I
Published: January 2007

Background and purpose:

A new concept for the inhibition of CGRP signalling has been developed by interaction with the CGRP moleculeper seby using a CGRP antibody or a CGRP binding RNA‐Spiegelmer (NOX‐C89). We have compared these CGRP scavengers with two known receptor antagonists (CGRP8–37and BIBN4096BS) on CGRP‐induced relaxations in the rat middle cerebral artery (MCA). Furthermore, the role of the endothelial barrier has been studied.

Experimental approach:

We used the luminally perfused MCA in an arteriograph, pressurized to 85 mm Hg and myograph studies of isolated ring segments of the MCA.

Key results:

In myograph studies and in the perfusion system during abluminal application, αCGRP and βCGRP induced concentration‐dependent dilatation of the MCA. Given luminally neither peptide was significantly vasodilator. Adrenomedullin and amylin induced weak dilatations. In myograph experiments, relaxation induced by αCGRP was prevented by the four CGRP blockers (CGRP8–37, BIBN4096BS, the CGRP antibody and NOX‐C89.). In abluminal perfusion experiments, the relaxant response to αCGRP was prevented by these agents to a varying degree. Dilatation induced by abluminal application of αCGRP was inhibited by luminal CGRP8–37but not by luminal BIBN4096BS, CGRP antibody or NOX‐C89.

Conclusions and Implications:

α or βCGRP acted on smooth muscle cell CGRP receptors in rat MCA and were effectively prevented from reaching these receptors by the endothelial barrier. The CGRP blockers significantly inhibited αCGRP induced relaxation but were also prevented from reaching the CGRP receptors by the arterial endothelium.

British Journal of Pharmacology(2007)150, 633–640. doi:10.1038/sj.bjp.0707134
Rimonabant: more than an anti‐obesity drug?
Authors: Costa B
Published: January 2007

The endocannabinoid system modulates many pathophysiological functions, including the brain pathways involved in the regulation of body weight and adipose tissue function. The selective cannabinoid CB1 receptor antagonist, rimonabant, has undergone phase III clinical testing as anti‐obesity drug. Obesity is considered a mild inflammatory condition and predisposes individuals to an increased risk of developing many diseases. It has been recently suggested that a successful intervention to treat obesity is a therapy combining weight‐reducing drugs with anti‐inflammatory ones. In this scenario, rimonabant's anti‐obesity action is accompanied by favorable changes in markers for insulin resistance, C‐reactive protein, adiponectin, tumor necrosis factor α (TNFα). The results reported by Croci and Zarini in this issue highlight the anti‐inflammatory and anti‐hyperalgesic effect of rimonabant in obese animals, so suggesting that it could provide a more general and aggressive strategy to protect obese patients from many pathological risks.

British Journal of Pharmacology (2007) 150, –. 22 January 2007; doi:10.1038/sj.bjp.0707139
Optimized end station and operating protocols for reflection extended x-ray absorption fine structure (ReflEXAFS) investigations of surface structure at the European Synchrotron Radiation Facility beamline BM29
Authors: López-Flores Víctor , Ansell Stuart , Bowron Daniel T. , Díaz-Moreno Sofía , Ramos Silvia , Muñoz-Páez Adela
Published: January 2007

The development of the capability to engineer the surface properties of materials to match specific requirements demands high quality surface characterization techniques. The ideal tool should provide chemically specific structural characterization as well as surface sensitivity and depth profiling. Ideally the characterization method should also be applicable to systems both with and without long range order. X-ray absorption spectroscopy fine structure, when using the standard transmission detection system, provides all this information with the significant exception of surface sensitivity. In contrast, by detecting the reflected instead of the transmitted beam, it encompasses all these requirements because when the incident beam impinges onto a sample surface at glancing angles, in conditions close to the total reflection, only the outermost regions of the system under study are sampled. Such a technique provides information about the local structure as a function of depth as well as thin layer structure in the case of layered samples. Although it is potentially the ideal tool to study surface modified materials, experimental difficulties have hampered its widespread use in the fields of surface and materials sciences. As a solution to the experimental challenges, we provide a detailed description of an appropriate experimental station, the sample requirements, the measuring protocols, and software routines needed to optimize the collection of the data. To illustrate the capabilities of the technique the results obtained for a model multilayer sample are presented and analyzed under the total external reflection approximation.
Circular ‘after-Images’ following Observation of Rotating Linear Patterns
Authors: Wade N J
Published: January 2007

Prolonged observation of a slowly rotating grating results in the appearance of concentric circles upon viewing an homogeneous surface.
The Schrödinger Equation in Binocular Brightness Combination
Authors: MacLeod D I A
Published: January 2007

Schrödinger once proposed a simple rule to describe how binocular brightness depends upon the inputs from left and right eyes in situations where the two eyes receive different light intensities. It is shown that Schrödinger's suggestion can account for the main features of Levelt's recent data if it is assumed that each monocular response varies linearly with the logarithm of the light intensity.
Effects of Movements upon the Appearance and Duration of a Prolonged Visual Afterimage: 1. Changes Arising from the Movement of a Portion of the Body Incorporated in the Afterimaged Scene
Authors: Davies P
Published: January 2007

Gregory et al. (1959) reported qualitative changes in the appearance of a prolonged visual afterimage (viewed in total darkness) which arise from body movements. This paper (part 1 of a two part series) reports an experiment in which 12 subjects were required to observe an afterimage (in total darkness) of no, one, or both of their hands against a simple background. Movement of the hands during the observation period gave rise to qualitative changes in the appearance, and quantitative changes in the duration, of the afterimage. The former were confined to the portion of the afterimage corresponding to the moved hand, and the duration of the afterimage increased with the more complex changes in the scene. As kinaesthetic and proprioceptive information that conflicts with the visual input affects both the duration and the appearance of the afterimage, the data offer some support for the hypothesis that the duration and appearance of a visual afterimage may not be solely dependent upon retinal processes.
Fusion and Rivalry of Illusory Contours
Authors: Harris J P , Gregory R L
Published: January 2007

The general question is raised: “Are visual contours given directly from striate-cortex feature-detector activity?‘’ Phenomena of ‘subjective’ or ‘cognitive’ contours are examined to challenge this view, on the ground that contours can be extrapolations across low-probability gaps. The contours may be curved and may have poor ‘gestalt’ qualities—so ‘gestalt closure’ is not appropriate, but may be a sub-class of these phenomena. It is suggested that these illusory contours (and brightness differences) are generated by perceptually postulated masking objects—these being part of perceptual ‘scene analysis strategy’, since strong evidence for nearer objects is provided by improbable gaps.

Experiments are reported, in which each eye is given a different ‘cognitive’ contour figure such that there are disparate but illusory contours. It is found that these are fused to give three-dimensional illusory. surfaces bowing in front of the display. Masking objects must be in front of gaps; what happens here with reversal of stereo depth? Switching the eyes often gives rivalry of the illusory contours when masking is incompatible with the stereo depth. Implications for normal stereo vision are discussed.
The Separation of Bias and Sensitivity in Multiple-Choice Tasks
Authors: Ingleby J D
Published: January 2007

With the growing realisation by psychologists of the need to take account of response biases in perception and memory, the lack of a simple and realistic model to enable ‘sensitivity’ and ‘bias’ to be measured separately in complex tasks is becoming acute. Though signal-detection theory (TSD) has proved very useful in two-alternative tasks, it is virtually intractable in multiple-choice tasks; for this reason experimenters have tended to resort to Luce's Choice Model (LCM) as an approximation to it. The relationship between TSD and LCM, however, though close in the two-alternative case, becomes increasingly tenuous as the number of alternatives is increased. Nevertheless the substitution may still be made, provided certain cautions are observed: computer simulations have been used here to study both forced- and unforced-choice tasks, and establish guidelines for experimenters who wish to apply a two-factor analysis to data from complex tasks.
The Coordination of Visual Observation and Instrumental Behavior in Early Infancy
Authors: Kalnins Iize V , Bruner J S
Published: January 2007

Infants aged 5–12 weeks were shown a silent colour film whose clarity/focus was contingent on their sucking on a dummy nipple. In the ‘suck-for-clear’ condition the mean rate of sucking increased significantly over baseline level, and decreased when the contingency shifted to ‘suck-for-blur’. When the initial condition was suck-for-blur, sucking rate remained close to baseline level (even after the shift to suck-for-clear). Time spent looking at the clear film increased in both conditions, but there was little change in looking at the blurred pictures. With the introduction of the contingency conditions patterns of looking at the clearing and cleared pictures changed, and looking at the cleared picture increased in the suck-for-clear but not the suck-for-blur condition. Asymmetry of the results indicates that infants are better able to use an active response for instrumental means than to inhibit a response to achieve instrumental control. Implications for the development of voluntary control of action are explored.
‘On’ and ‘Off’ Components in the Human Somatosensory Evoked Response
Authors: Feinsod M , Bach-Y-Rita P , Madey J M , Simoes E
Published: January 2007

The somatosensory evoked response to vibrotactile stimuli was studied in 20 subjects. This type of response to stimuli of 1000 ms duration displays ‘on’ and ‘off’ components. The latter consists of a surface negative deflection of about 100–120 ms peak latency, followed by a slower positive wave. As in the averaged visual evoked response an afteractivity of frequency 8–10 Hz may follow the ‘on’ component. This activity may either mask the ‘off’ component, be initiated by the termination of the stimulus, or its rhythm can be interrupted by the stimulus end.

In view of the similarity between the averaged evoked response to visual and vibrotactile stimuli, it is suggested that visual and somatosensory information may be processed according to a common pattern.
Reversed Depth from Positive and Negative Stereograms
Authors: Rogers Brian J , Anstis Stuart M
Published: January 2007

A stereogram was presented with patterns of opposite contrast–one positive the other negative. One eye received only the positive pattern; the other received both positive and negative patterns superimposed. Subjects reported apparent reversals of perceived depth: crossed (convergent) disparity made the fused stereogram appear further away, whilst uncrossed (divergent) disparity made it appear nearer. It is believed that spatial summation in the visual system blurs the superimposed positive-and-negative contours and shifts their effective positions, leading to reversals in perceived disparity.
Visual Experience or Translation Rules? Drawing the Human Figure by Blind and Sighted Children
Authors: Millar Susanna
Published: January 2007

Figure drawings by 30 blind and 30 sighted children, tested under blindfold and visual conditions, were compared on positioning and drawing scores. Results showed that the majority of the blind, unlike the sighted made positioning errors, and were unaware of the correct placement rule. The older blind did not differ from the sighted on figure drawing, but the younger blind scored significantly worse. Blindfolded compared to visual conditions produced decrements mainly on cohesion and amount of detail by the sighted.

The findings suggest that drawing depends on the acquisition of translation rules for which prior visual experience is a facilitating but not a necessary condition. The absence of visual feedback during drawing seems to have detrimental effects mainly on the articulation of drawing.
The Visual Perception of Accelerated Motion
Authors: Schmerler John
Published: January 2007

The present research is an investigation of how changes in the rate of motion are perceived. Five separate experiments were performed with the use of filmed stimulus material and a variety of response measures, including both categorical judgments and reproduction techniques. It was found that (a) the smaller the ratio of terminal to initial velocity, the less frequent the judgments of acceleration or deceleration, (b) deceleration was significantly easier to perceive than acceleration, (c) the perception of acceleration was facilitated when the velocity of a lead-in segment was the same as the velocity at onset of motion, (d) a short tunnel centered in the motion path facilitated the perception of acceleration and deceleration, and (e) instantaneous changes in velocity were much more easily perceived than gradual changes. A one-event model for the perception of motion change in which there is a continuous interplay between earlier, later, and interpolated motion segments is favored over a two-event model in which earlier and later segments of velocity are compared.
Sex Differences in Visual Persistence: Experiments on the Ganzfeld and Afterimages
Authors: McGuinness Diane , Lewis Ian
Published: January 2007

Sex differences were investigated in two experiments on visual persistence: the Ganzfeld and the afterimage. Males were found to hold visual sensation longer than females, particularly in the Ganzfeld where there was little overlap of scores. Variability of experience in the Ganzfeld was also greater for males and they commonly reported ‘blank-out’ effects while females did not. There was further evidence from both experiments that females are more responsive to the long-wave region of the frequency spectrum.
Striate Cortex Potentials Related to Eye Movements in the Light and in Darkness in the Waking Human
Authors: Salzarulo Piero , Lairy Gabrielle C , Bancaud Jean
Published: January 2007

Potentials in relation to eye movements were studied by means of direct recording of the striate cortex in a waking man. In a lighted environment, the usual evoked potential—lambda response—was obtained and was clearly visible after each eye movement. In complete darkness no individual potential was observable by means of visual analysis after each eye movement, but a slow potential of low amplitude could be obtained by superimposition and averaging of the cortical striate activity time-locked to the start of a series of eye movements. This eye-movement potential showed a longer latency and a lower amplitude than the lambda response. These data are discussed in reference to those obtained in the cat and the monkey; the significance of this eye-movement potential in darkness as a ‘corollary discharge’ is considered.
The Aftereffect of Tracking Eye Movements
Authors: Morgan Michael J , Ward Roger M , Brussell Edward M
Published: January 2007

When observers tracked moving stripes across a background either of stationary stripes, or of stripes moving in the opposite direction, they saw a clear motion aftereffect when the stripes stopped moving. The direction of this aftereffect was opposite to that of the previously tracked stripes, and was thus the same as the direction of the retinal movement of the non-tracked stripes. This aftereffect of tracking was shown not to depend upon slippage of the tracked contours on the retina during tracking, or upon the saccadic phase of optokinetic nystagmus. The effect showed storage over a period of time with the eyes shut. It appears that the effect is due to induced movement, and arises originally from stimulation of the retina by background contours in the tracking phase. This was shown by confining the view of the moving target to one eye, while permitting both eyes to be exposed to background stimulation during tracking. After such stimulation the magnitude of the aftereffect was equal in the two eyes.
Pattern Evoked Average EEG Potentials and Dichoptic Visual Percepts
Authors: Lehmann Dietrich , Koukkou Martha , Dittrich Adolf
Published: January 2007

Monocular xenon flashes were used to evoke average EEG potentials while blank, dot or grid targets were shown simultaneously in ten dichoptic stimulus conditions, either continuously illuminated (added to the flashes, or contraocularly), or presented only by the flashes. Mean evoked-EEG-potential waveforms over repeated conditions were computed from average evoked potentials (EPs) for each stimulus condition and each hemisphere. Correlation coefficients were computed between mean-EP waveforms of all stimulus conditions for each subject. Mean correlation coefficients over subjects were treated in a cluster analysis to diagnose conditions associated with similar EP waveforms. Data from the two hemispheres yielded identical cluster results. Presence or absence of continuous target illumination for the flashed eye was the most powerful descriptor. Next important was continuously visible structure (regardless whether seen by the flashed or the nonflashed eye) in conditions with continuous illumination seen by the flashed eye, and flashed structure in conditions without continuous illumination for the flashed eye. It was concluded that a visual percept which enters the processor as non-EP-evoking information nevertheless is reflected by the EP waveform. However, the waveforms are different if the flashes carry the perceptual information exclusively. More powerful than visual structure is the mode of flash presentation (with or without continuous target illumination) for the EP waveform.
Visual Motion Detection Models: Features and Frequency Filters
Authors: Bonnet Claude
Published: January 2007

Two kinds of models have been proposed for taking into account the sensory processes at work in the detection of visual motion: the feature model and the frequency-filter model.

The problem of the complementarity of these models is raised. On the basis of empirical data, it is proposed that they are consistent.
Pictorial Perspective: Perception of Size, Linear, and Texture Perspective in Children and Adults
Authors: Hagen Margaret A , Glick Rochelle
Published: January 2007

Perception of size, linear, and texture perspective was investigated in third-grade and sixth-grade children and in college adults in three separate studies. A matching task required the observer to choose from a set of four alternative real scenes the correct match for the test stimulus, which was either a picture or a real scene. Correct performance required that the subject utilize perspective information for both size and distance relations. Erroneous choices available to the subject indicated errors in size judgment, in distance judgment, or in both simultaneously. View was either restricted at the correct station point or was free, with head motion. There were no significant effects of grade level. For all three groups, mean percent correct was nearly 100% with the real-scene test stimuli, and significantly below the chance level with the picture test stimuli. Errors in size judgment occurred most frequently, indicating that the geometrically correct rate of perspective convergence was too rapid to be seen by the subjects as perceptually acceptable. With size-perspective information alone, the number of size plus distance errors also increased significantly. There was no significant effect of viewing condition.
Illusory Contours Not Due to Completion
Authors: Kennedy John M
Published: January 2007

Illusory contour figures can arise in figures that do not require completion, and hence no appearance of overlap.
Levels of Stimulus Processing by the Squirrel Monkey: Relative and Absolute Judgements Compared
Authors: McGonigle Brendan O , Jones Barry T
Published: January 2007

Nine squirrel monkeys were required to select from various sets of stimuli—differing in size or brightness—either in terms of relational criteria or on an absolute stimulus basis. The level of information processing required by each task was assessed by means of stimulus transformation techniques, variations in set size, and by the elimination of the visible context. It was found that some relational judgements make fewer processing demands on the subject than do absolute stimulus judgements; the ‘middle’ relation, however, appears much more difficult to use than selection of a stimulus on an absolute basis and may be beyond the competence of the squirrel monkey. The results are seen as support for the thesis as advanced by McGonigle and Jones that the criteria of judgement, when varied, change the depth of stimulus processing by monkey as well as man.
Orientation Detectors in the Human Visual System and Figurai Aftereffects
Authors: Yoshida Toshiro
Published: January 2007

Figurai aftereffects were measured by using square patches of high-contrast grating on a dark background as inspection and test figures. The orientation of the outer square border and the enclosed grating were varied independently in order to evaluate their relative influence on the strength of the induced change of overall apparent size of the test figure. The largest effect is obtained when inspection and test figures are identical in the orientation of both outer border and enclosed grating. The strength of the aftereffect is reduced as a difference in orientation is introduced between inspection and test figure for either the outer contour or the contained grating, although the former is a more potent factor than the latter.
Frequency, Phase, and Colour Coding in Apparent Motion
Authors: Caelli Terry , Finlay David
Published: January 2007

We present some results which indicate that the known spatiotemporal limits for apparent motion are consistent with the motion being sinusoidal or a result of filtering. Given this we investigated how two such motions interact as a function of their relative temporal phase differences. This was accomplished by inducing two independent motions from complementary coloured event pairs. Results indicated critical phase limits for perceiving the two motions (red and green) which were consistent with the frequency specificity of the effect. The results are discussed within the framework of a filtering process for the perception of apparent motion.
Absolute and Relative Cues for the Auditory Perception of Egocentric Distance
Authors: Mershon Donald H , Bowers John N
Published: January 2007

Three experiments were performed to examine the reverberation cue to egocentric auditory distance and to determine the extent to which such a cue could provide ‘absolute’, as contrasted with ‘relative’, information about distance. In experiment 1 independent groups of blindfolded observers (200 altogether) were presented with broadband noise from a speaker at one of five different distances (0·55 to 8 m) in a normal hard-walled room. Half of each group of observers were presented with the sound at 0 deg azimuth, followed (after a delay) by the identical sound at 90 deg azimuth. The order of presentation was reversed for the remaining observers. Perceived distance varied significantly as a function of the physical distance to the speaker, even for the first presentations. The change in the binaural information between the 0 deg and 90 deg presentations did not significantly modify the results. For both orientations, near distances were overestimated and far distances were underestimated. Experiments 2 and 3 were designed to evaluate how much prior auditory exposure to the laboratory environment was necessary. A 200 Hz square-wave signal was presented from one of three distances (1, 2, or 6 m) to observers who had either minimal room information or an exposure which included talking within the room. Perceived distance varied significantly with physical distance regardless of exposure condition.
Visual-Geometric Illusions: Unisex Phenomena
Authors: Porac Clare , Coren Stanley , Girgus Joan S , Verde Mickey
Published: January 2007

The possibility of sex differences in responses to visual-geometric illusions was investigated with the use of forty-five illusion variants and a sample of 221 observers. No difference in illusion magnitude as a function of sex was found. A second experiment measured illusion decrement and transfer of decrement to other illusion configurations. Again there were no significant differences between male and female observers.
Frequency, Phase, and Colour Coding in Apparent Motion: 2
Authors: Finlay David , Caelli Terry
Published: January 2007

In an earlier paper, Caelli and Finlay demonstrated that the perception of apparent motion was contingent on critical phase relationships between inducing sources, and their spatio-temporal frequency ranges. In their original stimulus red-green centre-surround sources were used and phase-specific inhibition was found at 60°–90° phase angle differences between the complementarily coloured elements. In this experiment we show that, when centre-surround sources are replaced by vertically-horizontally displaced complementary (or identically coloured) sources, symmetrical phase inhibition effects occur with both motions.
Subjective Figures: Some Unusual Concomitant Brightness Effects
Authors: Parks Theodore E
Published: January 2007

Black-on-white displays are presented which are capable of producing subjective figures that are not enhanced in brightness.
Quantitative Studies of Some Dynamic Visual Effects
Authors: Barbur John L
Published: January 2007

The viewing of rotating or rapidly approaching one-dimensional periodic structures results in the perception of a high-contrast band on a uniform structureless surround. For rotating gratings, the width of the generated band is inversely proportional to the angular speed of rotation and the orientation of the band lags behind the direction perpendicular to the grating lines for both clockwise and anticlockwise rotation of the pattern. The amount of lag is proportional to the angular speed of rotation. The width of the band perceived during the viewing of an approaching or receding grating is inversely proportional to its speed, and the orientation of the generated band is along the direction of the lines in the grating.

A model is proposed which explains and predicts the effects observed during the viewing of one-dimensional periodic structures in terms of temporal luminance integration in the visual system. The extent to which temporal luminance integration is responsible for the perception of frame or element movement in multielement stimulus frames is also examined. The results obtained with monocularly or dichoptically presented multielement stimulus frames, as well as other relevant psychophysical and physiological data, suggest that the temporal integration responsible for the observed effects is associated with mechanisms of early-stage visual processing which must be located prior to the lateral geniculate nucleus level.
The Subjective Brightness of Illusory Figures: Is Stratification a Factor?
Authors: Parks Theodore E
Published: January 2007

An increase in factors which might contribute to apparent stratification was found to counteract the expected reduction in the subjective brightness of an illusory figure usually produced by decreasing the orthogonality of surrounding line segments and to enhance brightness when the degree of orthogonality was held constant.
Neuronal Circuits Capable of Generating Visual Cortex Simple-Cell Stimulus Preferences
Authors: Dobson Vernon G
Published: January 2007

The range of simple-cell stimulus preferences to be found at each point in the striate cortex can be accounted for in terms of a model of retinocortical and intracortical circuits. It is assumed that each hypercolumn represents a conformal logarithmic mapping of its aggregate field, or hyperfield. Retinal-unit-field centres within the same aggregate field are assumed to be nonoverlapping, and overlap between retinal centres is attributed to a marked overlap between adjacent aggregate fields. Unit-field centres are assumed to be arranged regularly along aggregate-field radii, with diameters which increase linearly with eccentricity. Retinal-unit-field centres project retinotopically to overlapping clusters consisting of nine cortical pillars, and each pillar receives from a corresponding cluster of nine retinal-unit-field centres. Under this mapping, aggregate-field radii project to orientation columns, and concentric semicircles project to spatial-frequency columns. Inhibitory basket-cell axons project at right angles to the orientation columns, in parallel with the spatial-frequency columns, to produce a range of preferences and tuning curves for orientation, symmetry, directionality, and length. The same circuits also offer explanations for adaptation phenomena such as tilt aftereffects, and suggest ways in which attentional mechanisms might operate.
Visual Images Observed following an Enucleation
Authors: Gillmor C Stewart
Published: January 2007

After enucleation of the right eye the author observed persistent and continuous visual images featuring angular groups of parallel-line segments which have continued for two years, to the present time, though considerably diminished. These phenomena are reported along with results of measurements of the images and of several simple experiments. Some quantitative comparisons are made to results from studies of macaque monkeys, and to human migraine fortification images.
Infant Response to Impending Optical Collision
Authors: Dunkeld Jane , Bower Tom G R
Published: January 2007

Young infants withdraw their heads when shown a display simulating a rectangle rotating towards their faces. The head withdrawal is specific to that transformation and is not elicited by a similar transformation which does not specify approach. This is possible evidence of an unlearned ability to pick up information about change of position in the third dimension.
Amblyopia Cannot Be Explained by considering Only Detection Thresholds
Authors: Hess Robert , Jenkins Steven
Published: January 2007

Threshold function and suprathreshold performance for nonacuity stimuli are compared for an amblyope who exhibits a low as well as a high spatial frequency threshold abnormality.

The results show that (i) a suprathreshold abnormality involving discrimination and localization of easily visible stimuli occurs in amblyopia and (ii) suprathreshold abnormalities occur in amblyopia independent of any threshold dysfunction.
The Role of Context in the Perception of Orientation by the Rat
Authors: Jones Barry T , Rana Ravi K , McGonigle Brendan O
Published: January 2007

Two experiments are reported which demonstrate the role of contextual factors in the rat's perception of orientation. Designed to eschew criticisms of an earlier study by McGonigle and Jones, the first experiment shows that the rat's perception of linear Gestalten is conditional upon the set of alternative patterns within which the (linear) pattern is embedded. The second experiment shows that the ecological framework of an orientational cue (rather than its position relative to retinocortical coordinates) determines the rat's perception of vertical and horizontal stimuli.
Tactile Pattern Perception
Authors: Loomis Jack M
Published: January 2007

Because efforts to use the cutaneous sense for conveying speech and visual information have met with only partial success, it would be useful to understand better the pattern-sensing capabilities of touch. This paper is an account of the sensory and perceptual factors known or hypothesized to limit the tactile perception of simple two-dimensional patterns, with special attention to the limited spatial bandwidth of touch.
The Determinants of Illusory-Contour Perception
Authors: Halpern Diane F
Published: January 2007

The term ‘illusory contours' refers to contours perceived where none physically exist. Three hypotheses that have been successful in their ability to account for this phenomenon invoke: (i) apparent depth; (ii) brightness contrast; and (iii) use of figural cues. An experiment has been designed to determine the extent to which each hypothesis accounts for the overall variation in subjects' responses to illusory contours when all three hypotheses are considered simultaneously. Experimental results suggest that different processes may assume a primary role in the perception of illusory contours depending upon the type of inducing area and the configuration. The results highlight the multifaceted nature of the processes involved, and indicate that no single theory can explain the perception of illusory contours.
Texture-Contrast Analogues of the Spillmann-Redies Effect (Research Note)
Authors: MacKay Donald M
Published: January 2007

It is argued that the induction of lattice-motion in the Spillmann-Redies phenomenon may be due to the inability of the illusory lattice-structure to stimulate the motion-signalling system.
The Impossible Dream of Fechner and Stevens
Authors: Weiss David J
Published: January 2007

The idea that there is a single psychophysical function which describes how the human responds to stimulus intensity is rejected. The form of any empirical function depends upon the buried yet arbitrary assumption about how the stimuli are to be measured. Because psychophysical functions have this arbitrary basis, there can be no universal law, and further, no psychophysical function can reveal a general truth about the nervous system. The power law has been inappropriately reified; the descriptive usefulness of the power function has been incorrectly extended, perhaps because simplicity is appealing.
On the Failure to Recognize the Back of One's Own Hand
Authors: Wuillemin Dianne , Richardson Barry
Published: January 2007

Subjects were able to discriminate photographs of their own hands from other hand photographs but were unable to recognize their hands amongst a group of other objects when they were unaware that their hands were in the photographed set. It was concluded that recognition of even this highly familiar stimulus is dependent upon selection of the appropriate identifying cues, and that this process depends on expectation.
Memory for Pictograms, Pictures, and Words Separately and All Mixed up
Authors: Haber Ralph Norman , Myers Barry L
Published: January 2007

Pictograms were created in which the outline of a word denoting an object was shaped to be the same as the object itself. A number of objects were presented, some drawn as pictograms, some as outline shapes, and some as normally printed words. The experiment was designed to test if recognition memory was superior for the pictograms as compared to outline pictures or words, and if this would be true whether the subjects were asked to attend to the form or only the content of the stimuli. One group of subjects was trained to respond OLD only if the test item was the same object in the same form, and NEW otherwise. The other group responded OLD if the test item was the same object in any form, and NEW only to objects never before shown in any form. Recognition accuracy (a signal detection analysis) was greatest for the pictograms, and poorest for the words in both groups. Though the subjects could disregard form, they were most accurate when probed with the same form as presented. But in all comparisons subjects were most accurate when forced to recall both the form and the content. These and other results were taken to be mildly supportive of a dual coding hypothesis, and of the utility of these new stimuli.
The Shape of Smooth Objects and the Way Contours End
Authors: Koenderink Jan J , van Doorn Andrea J
Published: January 2007

It is shown, by elementary mathematical reasoning, that visual contours can only be concave at their endpoints. This simple natural fact is contrasted with general mannerisms of draftsmen: in the great majority of cases contours are drawn to have convex ends. It is argued that this results from our general concept of solid shapes: a general shape is conceived of as a conglomerate of convex (‘ovoid’) elementary shapes, these shapes act as ‘figure’ and the way they are glued together is treated as the—relatively unimportant—‘ground’. The hypothesis is supported through citations from academic-art literature. An attempt is made to give a geometrical specification of just what draftsmen draw if they disregard the contour.
The Effect of Forward and Backward Masking by Flash on Apparent Size
Authors: Wilding John
Published: January 2007

Subjects observed a briefly exposed square and set a variable square to match its size. In experiment 1 the square was black or white and was preceded or followed by a flash of light. The preceding adaptation field was complete darkness or an illuminated field. Marked underestimation of size occurred when flash followed the square in all conditions, compared with trials with no flash. Preceding flash produced a small reversal of this effect, the extent of which depended on whether the square was black or white. Absence of an illuminated adaptation field reduced estimates in all conditions except those where flash preceded the square. In experiment 2, a black square was used, and the stimulus duration and the interval between stimulus and flash were varied. No significant effects were found with preceding flash. When flash followed the square, apparent size increased linearly over the first 300 ms with the logarithm of the interval between onset of the square and onset of the flash, then levelled off. Experiment 3 demonstrated that the reduction in apparent size occurred with figure and interfering flash delivered to the same eye but not with dichoptic interference. The results are explained by reference to a suggestion of Georgeson that the optimum frequency of spatially tuned receptors decreases in impoverished viewing conditions. Hence the presented figures trigger receptors which normally are responsive to smaller figures, and the presented figures are therefore categorized as being smaller than they really are.
Visual Perception of Relative Mass in Dynamic Events
Authors: Todd James T , Warren William H
Published: January 2007

Two experiments are reported which examine how the dynamic property of relative mass in collision events is specified by kinematic properties of a visual motion display. In most cases observers are accurate at detecting the ‘heavier’ of two objects, although they do not take advantage of the completely general optic information that is available. Instead, they rely on limited information that breaks down at extreme values of elasticity and relative initial velocity. In addition, observers appear to utilize different information for relative mass with different types of collisions. It is suggested that reliance on such limited information may be appropriate for perceivers operating in the restricted context of a terrestrial environment.
Perceptual Learning of Illusory Contours and Colour
Authors: Gellatly Angus R H
Published: January 2007

An adequate account of the phenomena of illusory contours (ICs) will require an understanding of the genesis of such effects. There are two main techniques used to study perceptual genesis: the first is to slow down the relevant perceptual processes and to study them during perceptual learning; the second employs tachistoscopic exposures and backward masking. To date the technique of perceptual learning has not been shown to be applicable in the case of ICs. Two experiments are reported in which perceptual learning is used to study ICs. It is demonstrated that subjects can learn to see, first, illusory contours and, second, illusory colour. The suggestion is made that although there may be different kinds of illusory phenomena which may arise in different ways, these may all depend upon a common set of mechanisms.
On the Relativity of Pitch
Authors: van den Brink G
Published: January 2007

The way we interpret a given set of sensory stimuli can depend very strongly on our choice of cues. The resulting ambiguity is particularly familiar in visual perception, and underlies many well-known visual illusions. It is shown that comparable ambiguities exist in the field of hearing, particularly pitch perception.
Stroboscopic Motion in Depth
Authors: Finlay David
Published: January 2007

Temporal limits of stroboscopic apparent motion in depth have been examined. For monocular viewing the limits are similar to those obtained for motion in the frontal plane, while those for binocular viewing are greatly narrowed. In another experiment the contraction in space over which apparent movement occurs was measured. The results are discussed in terms of a filter representation proposed by Caelli and Finlay.
Correspondence Strength in Apparent Movement as a Function of Short-Range and Long-Range Processes: Comments on Ullman (1980)
Authors: Petersik J Timothy , Boring Mark , McDill Melinda
Published: January 2007

It is argued that correspondence strength is a joint function of the relative activity of short-range and long-range processes and not solely a function of a single correspondence process, and this puts Ullman's interpretation of his results in doubt.