Postural instability marks a prevalent symptom of Parkinson’s disease. It often manifests in increased body sway, which is commonly assessed by tracking the Center of Pressure. Yet, in terms of postural control, the body’s Center of Mass, and not CoP is what is regulated in a gravitational field. The aim of this study was to explore the effect of early- to mid-stage PD on these measures of postural control in response to unpredictable visual perturbations. We investigated three cohorts: 18 (...) patients with early to mid-stage PD [Hoehn & Yahr stage ; 1.94 ± 0.70]; a group of 15 age-matched controls ; and a group of 12 young healthy adults. Participants stood on a force plate to track their CoP, while the movement of their entire body was recorded with a video-based motion tracking system to monitor their CoM. A moving room paradigm was applied through a head-mounted virtual reality headset. The stimulus consisted of a virtual tunnel that stretched in the anterior-posterior direction which either remained static or moved back and forth in an unpredictable fashion.We found differences in mean sway amplitude and mean velocities of CoP and CoM between the groups under both conditions, with higher MSA of CoP and CoM for PD and higher mean velocities of both variables for PD and ECT when compared with YCT. Visual perturbation increased mean CoP velocity in all groups but did not have effects on mean CoM velocity or MSA. While being significantly lower for the young adults, the net effect of visual perturbation on mean CoP velocity was similar between patients with PD and age-matched controls. There was no effect of the visual perturbation on mean CoM velocity for any of the groups.Our simultaneous assessment of CoP and CoM revealed that postural control is reflected differently in CoM and CoP. As the motion of CoM remained mostly unaffected, all groups successfully counteracted the perturbation and maintained their balance. Higher CoP velocity for PD and ECT revealed increased corrective motion needed to achieve this, which however was similar in both groups. Thus, our results suggest increased effort, expressed in CoP velocity, to be an effect of age rather than disease in earlier stages of PD. (shrink)

We present a computational model of multiple-object tracking that makes trial-level predictions about the allocation of visual attention and the effect of this allocation on observers' ability to track multiple objects simultaneously. This model follows the intuition that increased attention to a location increases the spatial resolution of its internal representation. Using a combination of empirical and computational experiments, we demonstrate the existence of a tight coupling between cognitive and perceptual resources in this task: Low-level tracking of objects generates (...) bottom-up predictions of error likelihood, and high-level attention allocation selectively reduces error probabilities in attended locations while increasing it at non-attended locations. Whereas earlier models of multiple-object tracking have predicted the big picture relationship between stimulus complexity and response accuracy, our approach makes accurate predictions of both the macro-scale effect of target number and velocity on tracking difficulty and micro-scale variations in difficulty across individual trials and targets arising from the idiosyncratic within-trial interactions of targets and distractors. (shrink)

We demonstrate “economies of experience” in eye-movement patterns—that is, optimization of eye-movement patterns aimed at more efficient and less costly visual processing, similar to the priming-induced formation of sparser cortical representations or reduced reaction times. Participants looked at Mooney-type, degraded stimuli that were difficult to recognize without prior experience, but easily recognizable after exposure to their undegraded versions. As predicted, eye-movement dispersion, velocity, and the number of fixations decreased with each stimulus presentation. Further analyses showed that this effect (...) was contingent on recognition, and the selection of information from the stimulus could be informed by the identity of the presented object. Finally, our study demonstrates that after exposure to the undegraded version of the stimulus, eye-movement patterns associated with its degraded and undegraded versions become more similar. This suggests that eye-movement patterns can evolve to facilitate the optimal processing of a given stimulus via experience-driven perceptual learning. (shrink)

ArgumentAfter having measured the velocity of the nervous impulse in the 1850s, Helmholtz began doing research on the temporal dimensions of visual perception. Experiments dealing with the velocity of propagation in nerves were carried out occasionally for some fifteen years until their final publication in 1871. Although the temporal dimension of perception seems to have interested Helmholtz less than problems of geometry and space, his experiments on the time of perception were technically rather subtle and seminal, especially (...) compared with experiments performed by his contemporaries, such as Sigmund Exner, William James, Rudolf Hermann Lotze, Ernst Mach, Wilhelm Volkmann, and Wilhelm Wundt. Helmholtz’s conception of the temporal aspects of perception reflects the continuity that holds between psychophysiological research and the Kantian philosophical background. (shrink)

According to the traditional inferential theory of perception, percepts of object motion or stationarity stem from an evaluation of afferent retinal signals (which encode image motion) with the help of extraretinal signals (which encode eye movements). According to direct perception theory, on the other hand, the percepts derive from retinally conveyed information only. Neither view is compatible with a perceptual phenomenon that occurs during visually induced sensations of ego motion (vection). A modified version of inferential theory yields a model in (...) which the concept of extraretinal signals is replaced by that of reference signals, which do not encode how the eyes move in their orbits but how they move in space. Hence reference signals are produced not only during eye movements but also during ego motion (i.e., in response to vestibular stimulation and to retinal image flow, which may induce vection). The present theory describes the interface between self-motion and object-motion percepts. An experimental paradigm that allows quantitative measurement of the magnitude and gain of reference signals and the size of the just noticeable difference (JND) between retinal and reference signals reveals that the distinction between direct and inferential theories largely depends on: (1) a mistaken belief that perceptual veridicality is evidence that extraretinal information is not involved, and (2) a failure to distinguish between (the perception of) absolute object motion in space and relative motion of objects with respect to each other. The model corrects these errors, and provides a new, unified framework for interpreting many phenomena in the field of motion perception. (shrink)

Christopher Peacocke has recently made an important and insightful effort to fashion a non-verificationist method for distinguishing sense from nonsense. The argument is subtle and complex, and varies somewhat with each of his three target ‘spurious hypotheses’: that if a perfect fission of one person into two were to occur, one and only one of the resulting persons would be identical with the original; that another person’s visual experience can be qualitatively different from your own when you are both (...) seeing the same object, even though your relevant brain states are physically identical and so are your environmental conditions; and that the entire material universe is moving undetectably at a particular uniform velocity with respect to absolute space. My own assessment of his efforts is that they are most successful against the third of these hypotheses, and that this is a function of the fact that of the three, it alone clearly employs a problematic concept- that of absolute location. However, my purpose here is not to engage in a comprehensive evaluation of Peacocke’s project; it is rather to defend the extreme inverted spectrum hypothesis against his attack. I shall argue not only that his argument against EISH fails, but that he is himself independently committed to its intelligibility. Beyond that, I shall point out some striking and, to my mind, welcome consequences of his plausible claims concerning the relations between his own proposal and certain other views concerning content theory; the consequences in question depend both on his positive proposal and on my reasons for rejecting his argument against the extreme inversion hypothesis. (shrink)

_Purpose:_ This study examined the relationship between the near dissociated phoria and disparity vergence eye movements. Convergence insufficiency (CI) patients before vergence therapy were compared to: (1) the same patients after vergence therapy; and (2) binocularly normal controls (BNC). _Methods:_ Sixteen subjects were studied—twelve BNC and four with CI. Measurements from the CI subjects were obtained before and after 18 h of vergence eye movement therapy. The near dissociated phoria was measured using the flashed Maddox rod technique. Vergence responses were (...) stimulated from 4° symmetrical disparity vergence step stimuli. The peak velocity of the vergence response and the magnitude of the fusion initiating component (FIC) from an independent component analysis (ICA) were calculated. A linear regression analysis was conducted studying the vergence peak velocity as a function of the near dissociated phoria where the Pearson correlation coefficient was computed. _Results:_ Before vergence therapy, the average with one standard deviation FIC magnitude of convergence responses from CI subjects was 0.29° ± 0.82 and significantly less than the FIC magnitude of 1.85° ± 0.84 for BNC ( p t -test reported that the FIC and near dissociated phoria before vergence therapy for CI subjects significantly increased to 1.49° ± 0.57 ( p p r = 0.87; p _Conclusion:_ The results have clinical translational impact in understanding the mechanism by which vergence therapy may be changing the vergence system leading to a sustained reduction in visual symptoms. (shrink)

Previous studies have shown different developmental trajectories for object recognition of solid and non-solid objects. However, there is no evidence as to whether infants have expectations regarding certain attributes of objects, such as surface hardness, in the absence of tactile information. In the present study, we examined infants’ perception of the hardness of object surfaces from visually presented penetration events using the familiarization–novelty preference procedure. Experiment 1 showed that by 11 months old infants distinguished a relatively soft surface from a (...) crusty surface based on changes in the velocity of a moving object as the moving object penetrated the surface of the target object. Experiment 2 ruled out the possibility that infants were merely sensitive to differences in the velocity changes in the stimuli. (shrink)

This article analyzes Galileo's mathematization of motion, focusing in particular on his use of geometrical diagrams. It argues that Galileo regarded his diagrams of acceleration not just as a complement to his mathematical demonstrations, but as a powerful heuristic tool. Galileo probably abandoned the wrong assumption of the proportionality between the degree of velocity and the space traversed in accelerated motion when he realized that it was impossible, on the basis of that hypothesis, to build a diagram of the (...) law of fall. The article also shows how Galileo's discussion of the paradoxes of infinity in the First Day of the Two New Sciences is meant to provide a visual solution to problems linked to the theory of acceleration presented in Day Three of the work. Finally, it explores the reasons why Cavalieri and Gassendi, although endorsing Galileo's law of free fall, replaced Galileo's diagrams of acceleration with alternative ones. (shrink)

Objective: This study aimed to investigate whether galvanic vestibular stimulation with stochastic noise modulates the body sway and muscle activity of the lower limbs, depending on visual and somatosensory information from the foot using rubber-foam.Methods: Seventeen healthy young adults participated in the study. Each subject maintained an upright standing position on a force plate with/without rubber-foam, with their eyes open/closed, to measure the position of their foot center of pressure. Thirty minutes after baseline measurements under four possible conditions performed (...) without nGVS, the stimulation trials were conducted under the same conditions in random order, which were then repeated a week or more later. The total center of pressure path length movement and COP movement velocity in the mediolateral and anteroposterior directions were recorded for 30 s during nGVS. Furthermore, electromyography activity of the right tibial anterior muscle and soleus muscle was recorded for the same time and analyzed.Results: Three-way analysis of variance and post-hoc multiple comparison revealed a significant increment in COP-related parameters by nGVS, and a significant increment in soleus muscle activity on rubber. There was no significant effect of eye condition on any parameter.Conclusions: During nGVS, body sway and muscle activity in the lower limb may be increased depending not on the visual condition, but on the foot somatosensory condition. (shrink)

When describing motion along both the horizontal and vertical axes, languages from different families express the elements encoding verticality before those coding for horizontality (e.g., going up right instead of right up). In light of the motor grounding of language, the present study investigated whether the prevalence of verticality in Path expression also governs the trajectory of arm biological movements. Using a 3D virtual-reality setting, we tracked the kinematics of hand pointing movements in five spatial directions, two of which implied (...) the vertical and horizontal vectors equally (i.e., up right +45° and bottom right −45°). Movement onset could be prompted by visual or auditory verbal cues, the latter being canonical in French (“en haut à droite”/up right) or not (“à droite en haut”/right up). In two experiments, analyses of the index finger kinematics revealed a significant effect of gravity, with earlier acceleration, velocity, and deceleration peaks for upward (+45°) than downward (−45°) movements, irrespective of the instructions. Remarkably, confirming the linguistic observations, we found that vertical kinematic parameters occurred earlier than horizontal ones for upward movements, both for visual and congruent verbal cues. Non-canonical verbal instructions significantly affected this temporal dynamic: for upward movements, the horizontal and vertical components temporally aligned, while they reversed for downward movements where the kinematics of the vertical axis was delayed with respect to that of the horizontal one. This temporal dynamic is so deeply anchored that non-canonical verbal instructions allowed for horizontality to precede verticality only for movements that do not fight against gravity. Altogether, our findings provide new insights into the embodiment of language by revealing that linguistic path may reflect the organization of biological movements, giving priority to the vertical axis. (shrink)

In this study of the functionally referential alarm calls in the meerkats, we tested the hypothesis that the ability to refer to a specific location was an important factor in the evolution of discrete vocalizations. We investigated what information receivers gained about the location of the predator from alarm calls with high stimulus specificity compared to alarm calls with low stimulus specificity. Furthermore, we studied whether visual cues about the localization of the predator may be available from the posture (...) of the caller. We described the general behaviour of the caller, the caller’s posture, and in particular its gaze direction. We then observed receivers responding to the different call types, to determine whether the acoustic structure of the calls was enough for them to respond in the appropriate way, or whether they used additional visual cues from the caller. We tested this with specific manipulation experiments, using three set ups of playback experiments: no caller visible; model guard with specific gaze direction; and live sentinel. Natural observations and experiments confirmed that in high urgency situations the meerkats have enough information from the acoustic structure of the call to respond appropriately. When hearing low urgency calls that are less stimuli specific, meerkats used visual cues as an additional source of information in a few cases. This may indicate that functionally referential calls evolved to denote the location of the predator, rather than the predator type or its velocity of approach. However, when discussing this result in comparison to other functionally referential calls, such as the food associated calls and recruitment calls, this localization hypothesis does not appear to apply to the functionally referential calls in general. (shrink)

Motion pose capture technology can effectively solve the problem of difficulty in defining character motion in the process of 3D animation production and greatly reduce the workload of character motion control, thereby improving the efficiency of animation development and the fidelity of character motion. Motion gesture capture technology is widely used in virtual reality systems, virtual training grounds, and real-time tracking of the motion trajectories of general objects. This paper proposes an attitude estimation algorithm adapted to be embedded. The previous (...) centralized Kalman filter is divided into two-step Kalman filtering. According to the different characteristics of the sensors, they are processed separately to isolate the cross-influence between sensors. An adaptive adjustment method based on fuzzy logic is proposed. The acceleration, angular velocity, and geomagnetic field strength of the environment are used as the input of fuzzy logic to judge the motion state of the carrier and then adjust the covariance matrix of the filter. The adaptive adjustment of the sensor is converted to the recognition of the motion state. For the study of human motion posture capture, this paper designs a verification experiment based on the existing robotic arm in the laboratory. The experiment shows that the studied motion posture capture method has better performance. The human body motion gesture is designed for capturing experiments, and the capture results show that the obtained pose angle information can better restore the human body motion. A visual model of human motion posture capture was established, and after comparing and analyzing with the real situation, it was found that the simulation approach reproduced the motion process of human motion well. For the research of human motion recognition, this paper designs a two-classification model and human daily behaviors for experiments. Experiments show that the accuracy of the two-category human motion gesture capture and recognition has achieved good results. The experimental effect of SVC on the recognition of two classifications is excellent. In the case of using all optimization algorithms, the accuracy rate is higher than 90%, and the final recognition accuracy rate is also higher than 90%. In terms of recognition time, the time required for human motion gesture capture and recognition is less than 2 s. (shrink)

Performance and control of upright bipedal posture requires a constant and dynamic integration of relative contributions of different sensory inputs (i. e., sensory reweighting) to enable effective adaptations as individuals face environmental changes and perturbations. Children with gymnastic experience showed balance performance closer to that of adults during and after proprioceptive alteration than children without gymnastic experience when their center of pressure (COP) was analyzed. However, a particular COP sway can be achieved through performing and coordinating different postural movements. The (...) aim of this study was to assess how children and adults of different gymnastic experience perform and control postural movements while they have to adjust balance during and after bilateral tendon vibration. All participants were equipped with spherical markers attached to their skin and two vibrators strapped over the Achilles tendons. Bipedal stance was performed in three 45-s trials in two visual conditions (eyes open, EO, and eyes closed, EC) ordered randomly in which vibration lasted 10 s. Posture movements were analyzed by a principal component analysis (PCA) calculated on normalized and weighted markers coordinates. The relative standard deviation of each principal movement component (principal position, PP-rSTD) quantified its contribution to the whole postural movements, i.e., quantified the coordinative structure. The first (principal velocities, PV-rSTD) and second (principal accelerations, PA-rSTD) time-derivatives characterized the rate-dependent sensory information associated with and the neuromuscular control of the postural movements, respectively. Children without gymnastic experience showed a different postural coordinative structure and different sensory-motor control characteristics. They used less ankle movements in the anterior-posterior direction but increased ankle movements in medio-lateral direction, presented larger hip and trunk velocities, and exhibited more hip actions. Gymnastic experience during childhood seemed to benefit the development of proprioceptive reweighting processes in children, leading to a more mature form of coordinating and controlling posture similarly to adults. (shrink)

It is often assumed that the reaction time of a saccade toward visual and/or auditory stimuli reflects the sensitivities of our oculomotor-orienting system to stimulus saliency. Endogenous factors, as well as stimulus-related factors, would also affect the saccadic reaction time. However, it was not clear how these factors interact and to what extent visual and auditory-targeting saccades are accounted for by common mechanisms. The present study examined the effect of, and the interaction between, stimulus saliency and audiovisual spatial (...) congruency on the SRT for visual- and for auditory-target conditions. We also analyzed pre-target pupil size to examine the relationship between saccade preparation and pupil size. Pupil size is considered to reflect arousal states coupling with locus-coeruleus activity during a cognitive task. The main findings were that the pattern of the examined effects on the SRT varied between visual- and auditory-auditory target conditions, the effect of stimulus saliency was significant for the visual-target condition, but not significant for the auditory-target condition, Pupil velocity, not absolute pupil size, was sensitive to task set, and there was a significant correlation between the pre-saccade absolute pupil size and the SRTs for the visual-target condition but not for the auditory-target condition. The discrepancy between target modalities for the effect of pupil velocity and between the absolute pupil size and pupil velocity for the correlation with SRT may imply that the pupil effect for the visual-target condition was caused by a modality-specific link between pupil size modulation and the SC rather than by the LC-NE system. These results support the idea that different threshold mechanisms in the SC may be involved in the initiation of saccades toward visual and auditory targets. (shrink)

Numerous studies have focused on the understanding of rapid automatized naming, which can be applied to predict reading abilities and developmental dyslexia in children. Eye tracking technique, characterizing the essential ocular activities, might have the feasibility to reveal the visual and cognitive features of RAN. However, traditional measures of eye movements ignore many dynamical details about the visual and cognitive processing of RAN, and are usually associated with the duration of time spent on some particular areas of interest, (...) fixation counts, revisited fixation counts, saccadic velocities, or saccadic amplitudes. To cope with this drawback, we suggested an entropy-based method to measure eye movements for the first time, which first mapped eye movements during RAN in a time-series and then analyzed the time-series by a proper definition of entropy from the perspective of information theory. Our findings showed that the entropy was more sensitive to reflect small perturbation of eye movements, and thus gained better performance than traditional measures. We also verified that the entropy of eye movements significantly deceased with the age and the task complexity of RAN, and significantly correlated with traditional eye-movement measures [e.g., total time of naming ] and the RAN-related skills [e.g., selective attention, cognitive speed, and visual-motor integration]. Our findings may bring some new insights into the understanding of both RAN and eye tracking technique itself. (shrink)

Background: Parkinson’s disease is a neurodegenerative disease in which the progressive loss of dopaminergic neurons leads to initially sporadic and eventually widespread damage of the nervous system resulting in significant musculoskeletal and cognitive deterioration. Loss of motor function alongside increasing cognitive impairment is part of the natural disease progression. Gait is often considered an automatic activity; however, walking is the result of a delicate balance of multiple systems which maintain the body’s center of mass over an ever-changing base of support. (...) It is a complex motor behavior that requires components of attention and memory to prevent falls and injury. In addition, evidence points to the critical role of salient visual information to gait adaptability. There is a growing understanding that treatment for PD needs to address movement as it occurs naturally and walking needs to be practiced in more complex environments than traditional therapy has provided.MethodsIn this single-blinded randomized-controlled pilot study, an immersive treadmill training was piloted to determine feasibility and preliminary efficacy on gait and cognition in people with PD. Eighteen participants with Hoehn and Yahr stages I-III PD were randomized to either an intervention or a waitlist control group. Following baseline data collection, the intervention group trained for 30 min, three times/week for 4 weeks on a split belt treadmill combined with a first-person immersive video game targeting visuospatial skills and working memory. Assessment was repeated after 4 weeks of training for the experimental group and 1-month after baseline for the control group. Primary motor outcomes were captured with the APDM Opal sensors during 6 MWT, TUG, and TUG Cognitive. Secondary outcomes of cognition were measured with the Montreal Cognitive Assessment, Verbal Fluency and the Symbol Digit Modality Test. Within subject differences were calculated using the Wilcoxon Signed Ranked Test and between subject comparisons were analyzed using the Mann Whitney U-test.ResultsThis novel treadmill training program was well-tolerated with all participants in the intervention group completing 4 weeks of training three times a week without any adverse effects. After immersive cognitive motor training, the experimental group made clinically relevant improvements in gait speed and walking distance during the 6 MWT while members of the control group showed no change or decreased gait speed and walking distance over the 1-month trial. In addition, the experimental group demonstrated significant improvement for the TUG Cognitive and those changes were greater than the control group. The experimental group also improved scores on MoCA and SDMT cognitive outcome measures while the control group did not.ConclusionThe use of immersive gaming technology to engage specific areas of cognition related to gait is feasible in PD. The treadmill training program paired with a customized interactive video game improved walking velocity in addition to non-significant but consistent improvements in other gait measures and cognitive performance in participants with early to mid-stage PD. (shrink)

Virtual reality enables individuals to be exposed to naturalistic environments in laboratory settings, offering new possibilities for research in human neuroscience and treatment of mental disorders. We used VR to study psychological, autonomic and postural reactions to heights in individuals with varying intensity of fear of heights. Study participants were immersed in a VR of an unprotected open-air elevator platform in an urban area, while standing on an unstable ground. Virtual elevation of the platform elicited robust and reliable psychophysiological activation (...) including increased distress, heart rate, and electrodermal activity, which was higher in individuals suffering from fear of heights. In these individuals, compared with individuals with low fear of heights, the VR height exposure resulted in higher velocity of postural movements as well as decreased low-frequency body sway oscillations. This indicates that individuals with strong fear of heights react to heights with maladaptive rigidity of posture due to increased weight of visual input for balance control, while the visual information is less reliable at heights. Our findings show that exposure to height in a naturalistic VR environment elicits a complex reaction involving correlated changes of the emotional state, autonomic activity, and postural balance, which are exaggerated in individuals with fear of heights. (shrink)

Little is known about distance processing in patients with posterior brain damage. Although many investigators have claimed that distance estimates are normal or abnormal in some of these patients, many of these observations were made informally and the examiners often asked for relative, and not absolute, distance estimates. The present investigation served two purposes. First, we wanted to contrast the use of distance information in peripersonal space for perceptual report as opposed to visuomotor control in our visual form agnosic (...) patient, DF. Second, we wanted to see to what extent her abilities to process distance cues were dependent on binocular vision, in light of Milner et al.'s (1991) observations of preserved stereopsis in DF, and Dijkerman et al.'s (1996) and Marotta et al.'s (1997) observations that her visual guidance of grasping may be particularly dependent on binocular vision of the target. We hypothesized that DF's visuomotor responses would show normal sensitivity to target distance, while her perceptual estimates would not. In the first experiment, we required DF and two age- and sex-matched control subjects to reach out and grasp black cubes placed at varying distances, or to estimate the distance of the cubes from the hand starting position without making a reaching movement. In the second experiment, we required DF and two age-matched control subjects to point as rapidly and accurately as possible to small LED targets which differed in spatial location, under binocular and monocular conditions. The results showed that, relative to the control subjects, DF's grasping movements produced normal peak velocity-distance scaling-when she reached for blocks which varied in depth or pointed to LED targets which were presented at different distances in depth. In contrast, in the cube experiment, her verbal estimates of object distance were poorly scaled, although they improved slightly under the binocular conditions. The results are discussed in terms of current theories of processing streams in extrastriate visual cortex and the distinction between categorical and coordinate spatial processing. (shrink)

Christopher Peacocke has recently made an important and insightful effort to fashion a non-verificationist method for distinguishing sense from nonsense. The argument is subtle and complex, and varies somewhat with each of his three target ‘spurious hypotheses’: that if a perfect fission of one person into two were to occur, one and only one of the resulting persons would be identical with the original; that another person’s visual experience can be qualitatively different from your own when you are both (...) seeing the same object, even though your relevant brain states are physically identical and so are your environmental conditions; and that the entire material universe is moving undetectably at a particular uniform velocity with respect to absolute space. My own assessment of his efforts is that they are most successful against the third of these hypotheses, and that this is a function of the fact that of the three, it alone clearly employs a problematic concept- that of absolute location. However, my purpose here is not to engage in a comprehensive evaluation of Peacocke’s project; it is rather to defend the extreme inverted spectrum hypothesis against his attack. I shall argue not only that his argument against EISH fails, but that he is himself independently committed to its intelligibility. Beyond that, I shall point out some striking and, to my mind, welcome consequences of his plausible claims concerning the relations between his own proposal and certain other views concerning content theory; the consequences in question depend both on his positive proposal and on my reasons for rejecting his argument against the extreme inversion hypothesis. (shrink)

Ever since Clifford Geertz urged the “blurring of genres” in the social sciences, many scholars have considered the crossing of disciplinary boundaries a healthy alternative to rigidly maintaining them. But what precisely does the metaphor of “blurring” imply? By unpacking the varieties of visual experiences that are normally grouped under this rubric, this essay seeks to provide some precision to our understanding of the implications of fuzziness. It extrapolates from the blurring caused by differential focal distances, velocities of objects (...) in the visual field, and competing perspectival vantage points to comparable effects in the intersection of different scholarly disciplines. Arguing against the holistic implications of Geertz's metaphor, as well as the even more totalizing concept of “consilience” introduced by E. O. Wilson, it suggests that blurring implies new types of complexity between or among those disciplines. (shrink)

continent. 1.3 (2011): 208-212. … intervals of destructuring paradoxically carry the momentum for the ongoing process by which thought and perception are brought into relation toward transformative action. —Brian Massumi, Parables for the Virtual: Movement, Affect, Sensation 1 Facing a blank canvas or blank page is a moment of pure potential, one that can be enervating or paralyzing. It causes a pause, a hesitation, in anticipation of the moment of inception—even of one that never comes. The implication is that the (...) blank is yours in that moment, and it calls on you to act on it, to think into it, to create on it. Each blank canvas gives you time, of an undefined length, to transform that canvas’ inherent potential into a work. This two-dimensional plane of potential can be projected into a space, which the body can then occupy. When you “destructure” a space in the same way, prepare it to be a blank, much as you build a canvas, you allow your entire body to enter the space of potential, and you rest in anticipation of work, like the hand poised above the page. Artists have found that the deliberate creation of that space of potential through sealing the space and painting it white, thereby erasing details and distractions, can be such a transformative experience as to help define their whole practice. The cessation of distraction, the absence of indicator that a “blanked” workspace provides allows for a new presence of mind, it gives them the room, literally, to move into their work, and from there to move their work into the world. The workspace for the artist, the studio, is often perceived as a lab-like condensation of the gallery or museum, the traditional and idealized white cube. Similarly, with the blank page, a concrete relation between space and time comes forward as the intentional simplification of the architecture changes behavior and perception within the space. The work of “blanking” the studio space is a meditative reduction, an erasure, and in a way, an attempt at drawing away from the world beyond the studio - the sealed space is meant to recede from reality, to become abstracted by its willed lack of details and distractions. Within that space the time for a new beginning is made more present, more attainable, and the focus it fosters becomes another tool to aid creation. At the formative moment of his artistic practice, Tom Friedman used the blank of his studio, saturated in white, sealed off from the world, to fight velocity. He describes how he projected his vision of the end goal, the museum - a place he believes to be defined by slow contemplation - onto his own studio experience. He then sat and reflected on common objects, one by one, framed by the blank box he had created. The domestic objects he brought into the space to study foreshadow his mature works, where often the quotidian object has a single additional element – his intense labor. Friedman makes discrete objects through absurdly intense and focused labor, epitomized, perhaps by his 1,000 hours of Staring , made from 1992-97: Tom Friedman. 1000 Hours of Staring (1992-1997) His labor, to use his own words, is his way to “bring all of who you are to the experience.” Friedman shares his labor, allows the slow, deliberate pace of his work born in the studio to penetrate the museum. Nothing seems effortless, or a gesture, the labor is apparent, displayed, and tangible. He gives us the labor, the personal investment in the physical that saved art for him, that divorced the work from the language he cites as a factor of alienation. When we see his work we do not see words, we see acts, we see objects. He has forced the studio as workspace into the exhibition space, as he stuffs hundreds of more hours of labor into his shows with each new piece, filling the space with material and labor, material and labor – his involvement, his investment, is his gift to us as the viewers, as he introduces the laborious and contemplative pace he feels belongs to the museum. He saves us also from the alienation of language, which first drove him into the sealed studio and away from the discourse of his school. He presents us with his real, the object which stands in stark contrast to the white slate of the studio, the sealed white box he started from, where his individual, self-contained objects begin and end, completed through the intensity of isolation, first of the individual artist, and then of the material he chooses to slowly, slowly, slowly work: Tom Friedman. Untitled (1992) In his in-depth analysis of galleries as a blank white cube, Brian O’Doherty emphasizes the religious connotations implied in the strict laws of the exhibition space and the valuation, aesthetics and elements of control he feels it imposes upon the work. Like Friedman, he recognizes the power of the restricted space – indicating the “perceptual fields of force” – that act on any object introduced into it. Going beyond Friedman’s assessment of the space as highly utilitarian for focusing his perception, O’Doherty emphasizes the rejection of the physical body of the artist or observer, saying that the cube allows for only observation - eyes and mind. He later parallels the picture frame as a psychological container for the artist with the room as the same for the observer. In both cases, this is an emphasis on the alienating nature of the relationship – just as the artist is kept out of the frame by the picture, in the gallery the art forces the body of the spectator out, calling for a self-referential purity. Patrick Ireland. White Cube (1998) O’Doherty makes a point of saying that the installation shot of the gallery without figures is “one of the icons of our visual culture.” In recent years, however, installation shots have begun to include figures, in some cases they are essential to understanding the scale and even the nature of the work, specifically with work that captures the experience of the space and the way that it varies from a white cube. The work of Olafur Eliasson is a case in point, as the Danish artist uses elements of scientific and natural phenomena to alter perception within the controlled gallery environment, tweaking and redirecting O’Doherty’s “perceptual fields of force” to make points about the act of seeing, or seeing yourself seeing, to quote the artist. This indicates a shift in the role of the artwork, not to exclude the body and stand discretely and self-sufficiently, but to include it, to manipulate it and to make the observer aware of the nature of that manipulation and the work’s ability to manipulate. Olafur Eliasson. 360º room for all colours (2002) So though in O’Doherty’s analysis, the intense blankness of the gallery pushed the observer out in favor of the artwork’s isolation, artists can replicate this inhumane sterility in their own workspace to focus their work on the influence of the gallery right from inception. This can be interpreted as an almost opposite understanding of the purpose of sealing and whitewashing the workspace as stated by Friedman. He sought a refuge from the critical language of the art school, and a space that, like the museum, gave him a protracted sense of time, and, he felt, welcomed him in, “to bring all of who you are,” as opposed to O’Doherty’s feeling that the museum was asking you, at least in body, to leave, and allow the work to take on its own life. Friedman does not seem to imply the tension with the cube and critical stance that O’Doherty prioritizes. Where Friedman finds a refuge, O’Doherty defines an opponent. In a third position, Robert Irwin describes his sealed studio space as “the world.” Though he made the same effort as Friedman to seal out all influences and distractions, he implies that he is in dialogue with the world through his own concentration and perception. This is reminiscent of the nature of the monad, as interpreted by Deleuze, a unity that envelops a multiplicity, a sealed container that contains the universe. He went through the same ritual described by Friedman, sealing up the space, painting it white, and then forcing himself to remain inside, staring at his own work, training his concentration relentlessly. But he found that the room became the distraction: …he became aware that a thin crack along the wall a few yards away from the canvas likewise exerted its presence; that when he plastered that crack over and repainted the wall, the canvas itself presented an entirely new aspect.2 The context was in a relentless dialogue with the work, and trying to neutralize that dialogue, to mute the conversation between space and object, became part of his ritual as he “fixed” his space each day in the hope of total concentration on the work. Ultimately, Irwin shaped the trajectory of his art by relinquishing the studio, establishing a post-studio practice, where the work is conceived and created out in the world, in dialogue with the world and reflective of the conditions it finds surrounding it. The white cube failed to ever achieve neutrality, his heightened concentration prevented him from ever neutralizing the space, so, instead of continuing to try to maintain the charade of a perfect blank, he acknowledged the unstoppable voice of place and turned all his efforts onto the object and the world, as a constant dialogue. Some artists push their studio space far from purity, domesticating it like a lair or a living room, and others destroy it, fill it with chaos or detritus, blacken or clutter it so as never to be starting from a blank, and thereby try to avoid the anxiety of facing that void. Similarly artists may never prepare a white canvas, a clean page, a marble block, or other form that is intentionally lacking, in order to try to escape the dialogue with emptiness. But Irwin, like O’Doherty, found an opponent in the white cube, and he learned not to fight it, rather he ended the conflict by making it an ally, an interlocutor, a collaborator. We can vainly strive to start from nothing, to find the lull, the clearing, and to always consider what we do in balance with the empty set. Somehow that intangible cloud of hazy nothingness, that softness of a lapse continually offers a place to bounce off of, to react to, to wrestle with, to rest with, in tension, or a place to begin. Robert Irwin. Excursus: Homage to the Square3 (1998) NOTES 1 Massumi. Parables for the Virtual: Movement, Affect, Sensation. p271. 2 MOMA, NY. Eliasson, 360 ? Room for All Colours . Installation. 2002. (shrink)

In this paper, I take up the conciliatory-steadfast debate occurring within social epistemology in regards to the phenomenon of peer disagreement. I will argue, because the conciliatory perspective al-lows us to understand argumentation pragmatically—as a method of problem-solving within a community rather than as a method for obtaining the truth—that in most cases, we should not simply agree to disagree.

Recent studies in psychiatry reveal an acceptance of trauma through the media. Traditionally restricted to immediate experience, Post-traumatic Stress Disorder (PTSD) is now expanding to include mediated experience. How did this development come about? How does mediated trauma manifest itself? What are its consequences? This essay addresses these questions through three cases: (1) ‘trauma film paradigm’, an early 1960s research program that employed films to simulate traumatic effects; (2) the psychiatric study into the clinical effects of watching catastrophic events on (...) television, culminating with the September 11 attacks; (3) reports on drone operators who exhibit PTSD symptoms after flying combat missions away from the war zone. The recognition of mediated trauma marks a qualitative change in the understanding of media effects, rendering the impact literal and the consequences clinical. What informs recent speculations about the possibility of trauma through media is a conceptual link between visual media and contemporary conceptions of trauma. (shrink)

_Seeing the World through Children’s Eyes_ brings an overarching emphasis on ‘seeing’ to early years research and provides an opportunity to see and hear from leading researchers in the field concerning how they work with visual methodologies in their early years research.

Visual arguments can seem to require unique, autonomous evaluative norms, since their content seems irreducible to, and incommensurable with, that of verbal arguments. Yet, assertions of the ineffability of the visual, or of visual-verbal incommensurability, seem to preclude counting putatively irreducible visual content as functioning argumentatively. By distinguishing two notions of content, informational and argumentative, I contend that arguments differing in informational content can have equivalent argumentative content, allowing the same argumentative norms to be rightly applied (...) in their evaluation. (shrink)

In this article, after some thoughts on medieval logic and teaching, we present Thomas Murner’s text, Logica memorativa, showing some of his mnemonic strategies for the student to learn logic quickly. Murner offers a type of “flash cards” that illustrate much of the teaching of logic at the beginning of the sixteenth century. The first impression is visual, because the cards do not contain words that illustrate their content. Murner’s exposition rests on analogies between logic themes that are explained (...) and the visual images presented. (shrink)

Since its publication fifty years ago, this work has established itself as a classic. It casts the visual process in psychological terms and describes the creative way one's eye organizes visual material according to specific psychological premises. In 1974 this book was revised and expanded, and since then it has continued to burnish Rudolf Arnheim's reputation as a groundbreaking theoretician in the fields of art and psychology.

Experimental research has shown that pairs of stimuli which are congruent and assumed to 'go together' are recalled more effectively than an item presented in isolation. Will this multisensory memory benefit occur when stimuli are richer and longer, in an ecological setting? In the present study, we focused on an everyday situation of audio-visual learning and manipulated the relationship between audio guide tracks and viewed portraits in the galleries of the Tate Britain. By varying the gender and narrative style (...) of the voice-over, we examined how the perceived congruency and assumed unity of the audio guide track with painted portraits affected subsequent recall. We show that tracks perceived as best matching the viewed portraits led to greater recall of both sensory and linguistic content. We provide the first evidence that manipulating crossmodal congruence and unity assumptions can effectively impact memory in a multisensory ecological setting, even in the absence of precise temporal alignment between sensory cues. (shrink)

This volume consists of papers given to the Royal Institute of Philos ophy Conference on 'Philosophy and the Visual Arts: Seeing and Abstracting' given at the University of Bristol in September 1985. The contributors here come about equally from the disciplines of Philosophy and Art History and for that reason the Conference was hosted jointly by the Bristol University Departments of Philosophy and History of Art. Other conferences sponsored by the Royal Institute of Philosophy have been concerned with links (...) between Philosophy and related disciplines, but here, with the generous support of South West Arts and with the enthusiastic co-operation of the staff of the Arnolfini Gallery in Bristol we were able to attempt even more in the way of bridge building; not only were we able to hold some of our meetings in as possible to the general the Gallery, thus making them as accessible public, but we were also privileged in having our discussions supported by two exhibitions of contemporary painting that together presented contrasting aspects of the abstracting enterprise. One, featuring works by Ian McKeever, and drawings and painting by Frank Auerbach, some of which are discussed and illustrated in the present volume, was about the painterly exploration of 'abstracting from' images in nature and in painting itself. The other, curated by Waldemar Januszczak, while showing some figurative works, was concerned with the 'pure' power of colour perceived 'abstractly, in its own right. (shrink)

Direct realism in one form or another is gaining traction as an approach to perception. With the hope of bolstering such positions, we offer a framework upon which to base an argument for direct realism in matters of perception. Better yet, we offer an empirically supported framework. The framework on offer is that of ecological psychology. With the framework in place, we then discuss how it can address visual illusions, one of the major challenges facing proponents of direct realism.

Ordinary human perceivers know that visual objects are perceivable from standpoints other than their own. The aim of this paper is to provide an explanation of how perceptual experience equips perceivers with this knowledge. I approach the task by discussing a variety of action-based theories of perception. Some of these theories maintain that standpoint transcendence is required for shape perception. I argue that this standpoint transcendence must take place in the phenomenal present and that it can be explained in (...) terms of the experience of perceivers who jointly attend to an object. Joint perceivers experience objects as being perceived from standpoints other than their own. They operate in what I call “social space”, in which they single out objects by triangulating targets’ locations relative to their co-perceivers’ standpoints on these targets. It is then possible to explain the public character of the objects of individual experience by appeal to what I call “public space”. This is a spatial framework whose locations are presented as standpoints whence joint attention to the target would ensue, were they occupied by co-perceivers. If shape perception requires standpoint transcendence, then shape perceivers operate in public space and are thus capable of singling out targets by triangulating their locations from standpoints other than their own. If it doesn’t, then the introduction of a public spatial framework is an additional step whose introduction explains how perceivers come to experience objects as perceivable from standpoints other than their own. (shrink)

Sensorimotor expectations concern how visual experience covaries with bodily movement. Sensorimotor theorists argue from such expectations to the conclusion that the phenomenology of vision is constitutively embodied: objects within the visual field are experienced as 3-D because sensorimotor expectations partially constitute our experience of such objects. Critics argue that there are two ways to block the above inference: to explain how we visually experience objects as 3-D, one may appeal to such non-bodily factors as expectations about movements of (...) objects, not the perceiver, or to the role of mental imagery in visual experience. But instead of using sensorimotor expectations to explain how objects are experienced within the visual field, we can instead use them to explain our experience of the visual field itself and, in particular, our experience of its limits; that is, our ever-present visual sense of there being more to see, beyond what’s currently within the visual field. Crucially, this inference from sensorimotor expectations to the constitutive embodiment of visual phenomenology is not threatened by the above two challenges. I thus present here a sensorimotor theory of the phenomenology of the visual field, that is, our experience of our visual fields as such. (shrink)

This commentary on Jacob and Jeannerod’s Ways of Seeing evaluates the conclusions that the authors draw from the two visual systems hypothesis about the nature and phenomenology of visual experience.

A série tece caminhos imaginários cósmicos e políticos onde recrio a nossa existência.O árduo processo de cura está inserido nesse campo de força ancestral. A criação é uma estratégia de sobrevivência. O multidimensional como ruptura da linearidade para pensar a nossa reconstrução. É através de nossas complexidades que formamos constelações na precariedade. A trajetória indisciplinar se articula contra as estruturas verticais coloniais.

The proposed volumes are aimed at a multidisciplinary audience and seek to fill the gap between law, semiotics and visuality providing a comprehensive theoretical and analytical overview of legal visual semiotics. They seek to promote an interdisciplinary debate from law, semiotics and visuality bringing together the cumulative research traditions of these related areas as a prelude to identifying fertile avenues for research going forward. Advance Praise for Law, Culture and Visual Studies This diverse and exhilarating collection of essays (...) explores the many facets both historical and contemporary of visual culture in the law. It opens a window onto the substantive, jurisdictional, disciplinary and methodological diversity of current research. It is a cornucopia of materials that will enliven legal studies for those new to the field as well as for established scholars. It is a 'must read' that will leave you wondering about the validity of the long held obsession that reduces the law and legal studies to little more than a preoccupation with the word. Leslie J Moran Professor of Law, Birkbeck College, University of London Law, Culture and Visual Studies is a treasure trove of insights on the entwined roles of legality and visuality. From multiple interdisciplinary perspectives by scholars from around the world, these pieces reflect the fullness and complexities of our visual encounters with law and culture. From pictures to places to postage stamps, from forensics to film to folklore, this anthology is an exciting journey through the fertile field of law and visual culture as well as a testament that the field has come of age. Naomi Mezey, Professor of Law, Georgetown University Law Center, Washington, D.C., USA This highly interdisciplinary reference work brings together diverse fields including cultural studies, communication theory, rhetoric, law and film studies, legal and social history, visual and legal theory, in order to document the various historical, cultural, representational and theoretical links that bind together law and the visual. This book offers a breath-taking range of resources from both well-established and newer scholars who together cover the field of law's representation in, interrogation of, and dialogue with forms of visual rhetoric, practice, and discourse. Taken together this scholarship presents state of the art research into an important and developing dimension of contemporary legal and cultural inquiry. Above all, Law Culture and Visual Studies lays the groundwork for rethinking the nature of law in our densely visual culture: How are legal meanings produced, encoded, distributed, and decoded? What critical and hermeneutic skills, new or old, familiar or unfamiliar, will be needed? Topical, diverse, and enlivening, Law Culture and Visual Studies is a vital research tool and an urgent invitation to further critical thinking in the areas so well laid out in this collection. Desmond Manderson, Future Fellow, ANU College of Law / Research School of Humanities and the Arts, Australian National University, Australia. (shrink)

The task of visual search is to determine as rapidly as possible whether a target item is present or absent in a display. Rapidly detected items are thought to contain features that correspond to primitive elements in the human visual system. In previous theories, it has been assumed that visual search is based on simple two-dimensional features in the image. However, visual search also has access to another level of representation, one that describes properties in the (...) corresponding three-dimensional scene. Among these properties are three dimensionality and the direction of lighting, but not viewing direction. These findings imply that the parallel processes of early vision are much more sophisticated than previously assumed. (shrink)

This paper presents a study of the generation, manipulation and use of visual representations in different episodes of scientific discovery. The study identifies a common set of transformations of visual representations underlying the distinctive methods and imagery of different scientific fields. The existence of common features behind the diversity of visual representations suggests a common dynamical structure for visual thinking, showing how visual representations facilitate cognitive processes such as pattern-matching and visual inference through the (...) use of tools, technologies and other cultural resources. This dynamical model suggests a way of theorizing the interaction of cognitive, socio-cultural and technological aspects of science without losing sight of the essential contribution each makes to the processes of discovery. Whereas scientific work is often construed epistemically, as having the aim of improving the fit between theories and phenomena or culturally given notions of what counts as reality, this study shows that scientists use transformations to modify visual representations in ways that achieve other kinds of match: between a representation and the cognitive demands of a task or between an emerging representation and the social need to communicate and negotiate new meanings in a context of culturally embedded conventions. By showing how images connect each of the overlapping contexts of scientific work the proposed model negotiates the sometimes contested boundary between cognitive and social aspects of science. (shrink)