SoykaBB2013 3 F Soyka HH Bülthoff M Barnett-Cowan 2013-05-00 Epub ahead Experimental Brain Research In this paper, we show that differences in reaction times (RT) to self-motion depend not only on the duration of the profile, but also on the actual time course of the acceleration. We previously proposed models that described direction discrimination thresholds for rotational and translational motions based on the dynamics of the vestibular sensory organs (otoliths and semi-circular canals). As these models have the potential to describe RT for different motion profiles (e.g., trapezoidal versus triangular acceleration profiles or varying profile durations), we validated these models by measuring RTs in human observers for a direction discrimination task using both translational and rotational motions varying in amplitude, duration and acceleration profile shape in a within-subjects design. In agreement with previous studies, amplitude and duration were found to affect RT, and importantly, we found an influence of the profile shape on RT. The models are able to fit the measured RTs with an accuracy of around 5 ms, and the best-fitting parameters are similar to those found from identifying the models based on threshold measurements. This confirms the validity of the modeling approach and links perceptual thresholds to RT. By establishing a link between vestibular thresholds for self-motion and RT, we show for the first time that RTs to purely inertial motion stimuli can be used as an alternative to threshold measurements for identifying self-motion perception models. This is advantageous, since RT tasks are less challenging for participants and make assessment of vestibular function less fatiguing. Further, our results provide strong evidence that the perceived timing of self-motion stimulation is largely influenced by the response dynamics of the vestibular sensory organs. no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 15017 15422 SoykaRBB2011 3 F Soyka P Robuffo Giordano M Barnett-Cowan HH Bülthoff 2012-07-00 1 220 89 99 Experimental Brain Research Understanding the dynamics of vestibular perception is important, for example, for improving the realism of motion simulation and virtual reality environments or for diagnosing patients suffering from vestibular problems. Previous research has found a dependence of direction discrimination thresholds for rotational motions on the period length (inverse frequency) of a transient (single cycle) sinusoidal acceleration stimulus. However, self-motion is seldom purely sinusoidal, and up to now, no models have been proposed that take into account non-sinusoidal stimuli for rotational motions. In this work, the influence of both the period length and the specific time course of an inertial stimulus is investigated. Thresholds for three acceleration profile shapes (triangular, sinusoidal, and trapezoidal) were measured for three period lengths (0.3, 1.4, and 6.7 s) in ten participants. A two-alternative forced-choice discrimination task was used where participants had to judge if a yaw rotation around an earth-vertical axis was leftward or rightward. The peak velocity of the stimulus was varied, and the threshold was defined as the stimulus yielding 75 % correct answers. In accordance with previous research, thresholds decreased with shortening period length (from ~2 deg/s for 6.7 s to ~0.8 deg/s for 0.3 s). The peak velocity was the determining factor for discrimination: Different profiles with the same period length have similar velocity thresholds. These measurements were used to fit a novel model based on a description of the firing rate of semi-circular canal neurons. In accordance with previous research, the estimates of the model parameters suggest that velocity storage does not influence perceptual thresholds. no notspecified http://www.kyb.tuebingen.mpg.de/ published 10 15017 15422 BarnettCowanRB2012 3 M Barnett-Cowan SM Raeder HH Bülthoff 2012-07-00 1 220 41 50 Experimental Brain Research The perception of simultaneity between auditory and vestibular information is crucially important for maintaining a coherent representation of the acoustic environment whenever the head moves. It has been recently reported, however, that despite having similar transduction latencies, vestibular stimuli are perceived significantly later than auditory stimuli when simultaneously generated. This suggests that perceptual latency of a head movement is longer than a co-occurring sound. However, these studies paired a vestibular stimulation of long duration (~1 s) and of a continuously changing temporal envelope with a brief (10–50 ms) sound pulse. In the present study, the stimuli were matched for temporal envelope duration and shape. Participants judged the temporal order of the two stimuli, the onset of an active head movement and the onset of brief (50 ms) or long (1,400 ms) sounds with a square- or raised-cosine-shaped envelope. Consistent with previous reports, head movement onset had to precede the onset of a brief sound by about 73 ms in order for the stimuli to be perceived as simultaneous. Head movements paired with long square sounds (~100 ms) were not significantly different than brief sounds. Surprisingly, head movements paired with long raised-cosine sound (~115 ms) had to be presented even earlier than brief stimuli. This additional lead time could not be accounted for by differences in the comparison stimulus characteristics (temporal envelope duration and shape). Rather, differences between sound conditions were found to be attributable to variability in the time for head movement to reach peak velocity: the head moved faster when paired with a brief sound. The persistent lead time required for vestibular stimulation provides further evidence that the perceptual latency of vestibular stimulation is greater than the other senses. no notspecified http://www.kyb.tuebingen.mpg.de/ published 9 15017 15422 BarnettCowanMVTB2011 3 M Barnett-Cowan T Meilinger M Vidal H Teufel HH Bülthoff 2012-05-00 5 63 1 6 Journal of Visualized Experiments Path integration is a process in which self-motion is integrated over time to obtain an estimate of one's current position relative to a starting point 1. Humans can do path integration based exclusively on visual 2-3, auditory 4, or inertial cues 5. However, with multiple cues present, inertial cues - particularly kinaesthetic - seem to dominate 6-7. In the absence of vision, humans tend to overestimate short distances (<5 m) and turning angles (<30°), but underestimate longer ones 5. Movement through physical space therefore does not seem to be accurately represented by the brain. Extensive work has been done on evaluating path integration in the horizontal plane, but little is known about vertical movement (see 3 for virtual movement from vision alone). One reason for this is that traditional motion simulators have a small range of motion restricted mainly to the horizontal plane. Here we take advantage of a motion simulator 8-9 with a large range of motion to assess whether path integration is similar between horizontal and vertical planes. The relative contributions of inertial and visual cues for path navigation were also assessed. 16 observers sat upright in a seat mounted to the flange of a modified KUKA anthropomorphic robot arm. Sensory information was manipulated by providing visual (optic flow, limited lifetime star field), vestibular-kinaesthetic (passive self motion with eyes closed), or visual and vestibular-kinaesthetic motion cues. Movement trajectories in the horizontal, sagittal and frontal planes consisted of two segment lengths (1st: 0.4 m, 2nd: 1 m; ±0.24 m/s2 peak acceleration). The angle of the two segments was either 45° or 90°. Observers pointed back to their origin by moving an arrow that was superimposed on an avatar presented on the screen. Observers were more likely to underestimate angle size for movement in the horizontal plane compared to the vertical planes. In the frontal plane observers were more likely to overestimate angle size while there was no such bias in the sagittal plane. Finally, observers responded slower when answering based on vestibular-kinaesthetic information alone. Human path integration based on vestibular-kinaesthetic information alone thus takes longer than when visual information is present. That pointing is consistent with underestimating and overestimating the angle one has moved through in the horizontal and vertical planes respectively, suggests that the neural representation of self-motion through space is non-symmetrical which may relate to the fact that humans experience movement mostly within the horizontal plane. no notspecified http://www.kyb.tuebingen.mpg.de/ published 5 15017 15422 6730 3 M Barnett-Cowan LR Harris 2011-09-00 1 214 27 35 Experimental Brain Research The brain can know about an active head movement even in advance of its execution by means of an efference copy signal. In fact, sensory correlates of active movements appear to be suppressed. Passive disturbances of the head, however, can be detected only by sensory feedback. Might the perceived timing of an active head movement be speeded relative to the perception of a passive movement due to the efferent copy (anticipation hypothesis) or delayed because of sensory suppression (suppression hypothesis)? We compared the perceived timing of active and passive head movement using other sensory events as temporal reference points. Participants made unspeeded temporal order and synchronicity judgments comparing the perceived onset of active and passive head movement with the onset of tactile, auditory and visual stimuli. The comparison stimuli had to be delayed by about 45 ms to appear coincident with passive head movement or by about 80 ms to appear aligned with an active head movement. The slow perceptual reaction to vestibular activation is compatible with our earlier study using galvanic stimulation (Barnett-Cowan and Harris 2009). The unexpected additional delay in processing the timing of an active head movement is compatible with the suppression hypothesis and is discussed in relation to suppression of vestibular signals during self-generated head movement. no notspecified http://www.kyb.tuebingen.mpg.de/ published 8 6849 3 M Barnett-Cowan RW Fleming M Singh HH Bülthoff 2011-04-00 4 6 1 5 PLoS ONE Background How does the brain estimate object stability? Objects fall over when the gravity-projected centre-of-mass lies outside the point or area of support. To estimate an object's stability visually, the brain must integrate information across the shape and compare its orientation to gravity. When observers lie on their sides, gravity is perceived as tilted toward body orientation, consistent with a representation of gravity derived from multisensory information. We exploited this to test whether vestibular and kinesthetic information affect this visual task or whether the brain estimates object stability solely from visual information. Methodology/Principal Findings In three body orientations, participants viewed images of objects close to a table edge. We measured the critical angle at which each object appeared equally likely to fall over or right itself. Perceived gravity was measured using the subjective visual vertical. The results show that the perceived critical angle was significantly biased in the same direction as the subjective visual vertical (i.e., towards the multisensory estimate of gravity). Conclusions/Significance Our results rule out a general explanation that the brain depends solely on visual heuristics and assumptions about object stability. Instead, they suggest that multisensory estimates of gravity govern the perceived stability of objects, resulting in objects appearing more stable than they are when the head is tilted in the same direction in which they fall. no notspecified http://www.kyb.tuebingen.mpg.de/ published 4 15017 15422 6688 3 M Barnett-Cowan 2010-12-00 12 39 1684 1686 Perception Eating is a multisensory experience involving more than simply the oral sensation of the taste and smell of foods. It has been shown that the way foods look, sound, and feel like in the mouth all affect food perception. The influence of haptic information available when handling food is relatively unknown. In this study, blindfolded participants bit-into fresh or stale pretzels while rating their freshness-staleness and crispness-softness. Information provided to the hand was either congruent (whole pretzel fresh or stale) or incongruent (half pretzel fresh, half stale) with what was presented to the mouth. The results demonstrate that the perception of both freshness and crispness were systematically altered when incongruent information was provided: bit-into fresh pretzel-tips were perceived as staler and softer when a stale pretzel-tip was held in the hand and vice versa. Haptic information available when handling food thus plays a significant role in modulating food perception. no notspecified http://www.kyb.tuebingen.mpg.de/ published 2 15017 15422 6001 3 ML Cadieux M Barnett-Cowan DI Shore 2010-07-00 3 204 431 446 Experimental Brain Research A conflict between an egocentric and an external reference frame can be highlighted by examining the marked deficit observed with tactile temporal order judgments (TOJ) when the hands are crossed. The anecdotally-reported large individual differences in the magnitude of this crossed-hands deficit were explored here by testing a large group of participants (48; 24 female). Given that females have been shown to be more visually dependent than males in the potentially related rod-and-frame test (RFT), we hypothesized that females would show a larger influence of the external reference frame (i.e., a larger crossed-hands deficit). As predicted, female participants produced larger tactile TOJ deficits compared to our male participants. We also administered the RFT in these participants with hands crossed and uncrossed. Crossing the hands increased the effect of the frame in the RFT, more so for females than males, further highlighting the potential difference in the way that each sex accommodates reference frame c onflicts. Finally, examining the relation between the two tasks revealed a significant correlation, with larger frame effects associated with larger crossed-hands TOJ deficits, but this only held for males. We speculate that sex-specific differences in multisensory processing and spatial ability may explain why females are less able to disambiguate a crossed-hands posture than are males. no notspecified http://www.kyb.tuebingen.mpg.de/ published 15 15017 15422 6126 3 M Barnett-Cowan RT Dyde S Fox E Moro WD Hutchison LR Harris 2010-06-00 4 167 1138 1150 Neuroscience Perception of the relative orientation of the self and objects in the environment requires integration of visual and vestibular sensory information, and an internal representation of the body's orientation. Parkinson's disease (PD) patients are more visually dependent than controls, implicating the basal ganglia in using visual orientation cues. We examined the relative roles of visual and non-visual cues to orientation in PD using two different measures: the subjective visual vertical (SVV) and the perceptual upright (PU). We tested twelve PD patients (nine both on- and off-medication), and thirteen age-matched controls. Visual, vestibular and body cues were manipulated using a polarized visual room presented in various orientations while observers were upright or lying right-side-down. Relative to age-matched controls, patients with PD showed more influence of visual cues for the SVV but were more influenced by the direction of gravity for the PU. Increased SVV visual dependence corresponded with equal decreases of the contributions of body sense and gravity. Increased PU gravitational dependence corresponded mainly with a decreased contribution of body sense. Curiously however, both of these effects were significant only when patients were medicated. Increased SVV visual dependence was highest for PD patients with left-side initial motor symptoms. PD patients when on and off medication were more variable than controls when making judgments. Our results suggest that (i) PD patients are not more visually dependent in general, rather increased visual dependence is task specific and varies with initial onset side, (ii) PD patients may rely more on vestibular information for some perceptual tasks which is reflected in relying less on the internal representation of the body, and (iii) these effects are only present when PD patients are taking dopaminergic medication. no notspecified http://www.kyb.tuebingen.mpg.de/ published 12 6087 3 M Barnett-Cowan RT Dyde C Thompson LR Harris 2010-06-00 10 31 1899 1907 European Journal of Neuroscience Females have been reported to be more ‘visually dependent’ than males. When aligning a rod in a tilted frame to vertical, females are more influenced by the frame than are males, who align the rod closer to gravity. Do females rely more on visual information at the cost of other sensory information? We compared the subjective visual vertical and the perceptual upright in 29 females and 24 males. The orientation of visual cues presented on a shrouded laptop screen and of the observer’s posture were varied. When upright, females’ subjective visual vertical was more influenced by visual cues and their responses were more variable than were males’. However, there were no differences between the sexes in the perceptual upright task. Individual variance in subjective visual vertical judgments and in the perceptual upright predicted the level of visual dependence across both sexes. When lying right-side down, there were no reliable differences between the sexes in either measure. We conclude that heightened ‘visual dependence’ in females does not generalize to all aspects of spatial processing but is probably attributable to task-specific differences in the mechanisms of sensory processing in the brains of females and males. The higher variability and lower accuracy in females for some spatial tasks is not due to their having qualitatively worse access to information concerning either the gravity axis or corporeal representation: it is only when gravity and the long body axis align that females have a performance disadvantage. no notspecified http://www.kyb.tuebingen.mpg.de/ published 8 6000 3 M Barnett-Cowan LR Harris 2009-09-00 2-3 198 221 231 Experimental Brain Research Different senses have different processing times. Here we measured the perceived timing of galvanic vestibular stimulation (GVS) relative to tactile, visual and auditory stimuli. Simple reaction times for perceived head movement (438 +/- 49 ms) were significantly longer than to touches (245 +/- 14 ms), lights (220 +/- 13 ms), or sounds (197 +/- 13 ms). Temporal order and simultaneity judgments both indicated that GVS had to occur about 160 ms before other stimuli to be perceived as simultaneous with them. This lead was significantly less than the relative timing predicted by reaction time differences compatible with an incomplete tendency to compensate for differences in processing times. no notspecified http://www.kyb.tuebingen.mpg.de/ published 10 5999 3 M Barnett-Cowan LR Harris 2008-11-00 1242 231 243 Brain Research no notspecified http://www.kyb.tuebingen.mpg.de/ published 12 5998 3 M Barnett-Cowan RT Dyde LR Harris 2005-03-00 1039 314 324 Annals of the New York Academy of Sciences In order to test whether the control of eye movement in response to head movement requires an internal model of head orientation or instead can rely on directly sensing information about head orientation and movement, perceived gravity was separated from physical gravity to see which dominated the eye-movement response. Internal model theory suggests that the oculomotor response should be driven by perceived, internalized gravity, whereas the direct sensing theory predicts it should always be driven by vestibularly sensed gravity. Subjects lay on an airbed either supine or on their side and were sinusoidally translated along their dorsoventral body axis. The direction of perceived gravity was separated from physical gravity by performing the experiments in a room built on its side with the direction of its "floor" orthogonal to both physical gravity and the subject&amp;lsquo;s translation. The swinging sum of the imposed sinusoidal acceleration with physical gravity was thus in a plane orthogon al t o its sum with perceived gravity. Oculomotor responses to these swinging vectors were looked for and responses were found only to the sum of the acceleration with physical gravity, not perceived gravity. It was concluded that an internal model is not used to drive these compensatory eye movements. no notspecified http://www.kyb.tuebingen.mpg.de/ published 10 5997 3 M Barnett-Cowan M Peters 2004-07-00 2 55 275 276 Brain and Cognition Subjects had to judge the size of a tactile stimulus held in the unseen hand, while a visible phantom hand representing that unseen hand held a tactile stimulus of same or different size. No asymmetries in interference effects were found that could be related to hand or handedness. The method lends itself to quantification of virtual reality box illusions and can be used to evaluate the role of experience and sources of variability in the strength of the illusion across subjects. no notspecified http://www.kyb.tuebingen.mpg.de/ published 1 NestiMBRBP2012 7 A Nesti C Masone M Barnett-Cowan P Robuffo Giordano HH Bülthoff P Pretto Paris, France2012-09-00 1 6 Driving Simulation Conference Europe (DSC 2012) Due to limited operational space, in dynamic driving simulators it is common practice to implement motion cueing algorithms that tilt the simulator cabin to reproduce sustained accelerations. In order to avoid conflicting inertial cues, the tilt rate is kept below drivers’ perceptual thresholds, which are typically derived from the results of classical vestibular research where additional sensory cues to self-motion are removed. Here we conduct two experiments in order to assess whether higher tilt limits can be employed to expand the user’s perceptual workspace of dynamic driving simulators. In the first experiment we measure detection thresholds for roll in conditions that closely resemble typical driving. In the second experiment we measure drivers’ perceived realism in slalom driving for sub-, near- and supra-threshold roll rates. Results show that detection threshold for roll in an active driving task is remarkably higher than the limits currently used in motion cueing algorithms to drive simulators. Supra-threshold roll rates in the slalom task are also rated as more realistic. Overall, our findings suggest that higher tilt limits can be successfully implemented in motion cueing algorithms to better optimize simulator operational space. no notspecified http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/2012/DSC-2012-Nest.pdf published 5 15017 15422 BarnettCowan2010 2 M Barnett-Cowan McMaster University Press Hamilton, Ontario, Canada 2010-00-00 The Multisensory Mind no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 5996 2 M Barnett-Cowan McMaster University Press Hamilton, Ontario, Canada 2009-02-00 24 24 The Multisensory Mind no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 BarnettCowanSZGLd2011 46 M Barnett-Cowan F Soyka L Zaichik E Groen W Ledegang M de Mena 2011-00-00 2011-00-00 Analysis of perception data and motion perception criteria no notspecified 15017 15422 BeykirchBZBL2011 46 K Beykirch M Barnett-Cowan L Zaichik J Bos W Ledegang 2011-00-00 2011-00-00 Development of add-on perception model no notspecified 15017 15422 BeykirchSB2010 46 M Beykirch F Soyka M Barnett-Cowan 2010-00-00 2010-00-00 Evaluation of the baseline perception models and required amendments no notspecified 15017 15422 NestiBBP2012 7 A Nesti M Barnett-Cowan HH Bülthoff P Pretto Oxford, UK2012-06-21 167 13th International Multisensory Research Forum (IMRF 2012) The restricted operational space of dynamic driving simulators requires the implementation of motion cueing algorithms that tilt the simulator cabin to reproduce sustained accelerations. In order to avoid conflicting inertial cues, the tilt rate is limited below drivers’ perceptual thresholds, which are typically derived from the results of classical vestibular research, where additional sensory cues to self-motion are removed. These limits might be too conservative for an ecological driving simulation, which provides a variety of complex visual and vestibular cues as well as demands of attention which vary with task difficulty. We measured roll rate detection threshold in active driving simulation, where visual and vestibular stimuli are provided as well as increased cognitive load from the driving task. Here thresholds during active driving are compared with tilt rate detection thresholds found in the literature (passive thresholds) to assess the effect of the driving task. In a second experiment, these thresholds (active versus passive) are related to driving preferences in a slalom driving course in order to determine which roll rate values are most appropriate for driving simulators so as to present the most realistic driving experience. The results show that detection threshold for roll in an active driving task is significantly higher than the limits currently used in motion cueing algorithms, suggesting that higher tilt limits can be successfully implemented to better optimize simulator operational space. Supra-threshold roll rates in the slalom task are also rated as more realistic. Overall, our findings indicate that increasing task complexity in driving simulation can decrease motion sensitivity allowing for further expansion of the virtual workspace environment. no notspecified http://www.kyb.tuebingen.mpg.de/ published -167 15017 15422 Bulthoff2012_3 7 S Raeder HH Bülthoff M Barnett-Cowan Oxford, UK2012-06-19 32 13th International Multisensory Research Forum (IMRF 2012) The perception of simultaneity between auditory and vestibular information is crucially important for maintaining a coherent representation of the acoustic environment whenever the head moves. Yet, despite similar transduction latencies, vestibular stimuli are perceived significantly later than auditory stimuli when simultaneously generated (Barnett-Cowan and Harris, 2009; 2011). However, these studies paired a vestibular stimulation of long duration (~1 s) and of a continuously changing temporal envelope with brief (10-50 ms) sound pulses. In the present study the stimuli were matched for temporal envelope. Participants judged the temporal order of the onset of an active head movement and of brief (50 ms) or long (1400 ms) sounds with a square or raised-cosine shaped envelope. Consistent with previous reports, head movement onset had to precede the onset of a brief sound by about 73 ms in order to be perceived as simultaneous. Head movements paired with long square sounds (~100ms) were not significantly different than brief sounds. Surprisingly, head movements paired with long raised-cosine sound (~115 ms) had to be presented even earlier than brief stimuli. This additional lead time could not be accounted for by differences in the comparison stimulus characteristics (duration and temporal envelope). Rather, differences among sound conditions were found to be attributable to variability in the time for head movement to reach peak velocity: the head moved faster when paired with a brief sound. The persistent lead time required for vestibular stimulation provides further evidence that the perceptual latency of vestibular stimulation is larger compared to auditory stimuli. no notspecified http://www.kyb.tuebingen.mpg.de/ published -32 15017 15422 NestiBMB2012 7 A Nesti M Barnett-Cowan P MacNeilage HH Bülthoff Zürich, Switzerland2012-01-00 22nd Okulomotoriktreffen Zürich-München (ZüMü 2012) no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 15017 15422 SoykaRBB2012 7 F Soyka P Robuffo Giordano M Barnett-Cowan HH Bülthoff Zürich, Switzerland2012-01-00 22nd Okulomotoriktreffen Zürich-München (ZüMü 2012) no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 15017 15422 SoykaBRB2011 7 F Soyka M Barnett-Cowan P Robuffo Giordano HH Bülthoff Heiligkreuztal, Germany2011-10-00 42 12th Conference of Junior Neuroscientists of Tübingen (NeNA 2011) During eccentric yaw rotations around an Earth-vertical axis the semi-circular canals are stimulated (rotational acceleration) as well as the otoliths (tangential acceleration). Most likely the brain uses both sensory signals, the canal and the otolith signal, when faced with a rotation direction detection task. Keeping the rotational acceleration profile unchanged and increasing the radius of the eccentric rotation the tangential acceleration increases. Therefore, we hypothesized that thresholds would decrease with increasing radius of rotation. The threshold was defined as the peak acceleration needed to detect the correct direction of motion in 75% of the trials. Ten participants were tested in seven conditions (150 trials each): a head-centered rotation, a translation and five eccentric rotations with varying radii (R=0.1, 0.2, 0.3, 0.5, 0.8 m). The motion had 1s duration and consisted of a single cycle sinusoidal acceleration. Participants were blindfolded, heard white noise and their head was kept in place with a neck brace. The results show a significant decrease of thresholds with increasing radius. It can be seen that the detection process for eccentric rotations is not exclusively based on either the canal or the otolith signal, but that both signals are integrated. A model able to predict the thresholds of the eccentric rotations is proposed, which is solely based on the thresholds for the head-centered rotation and the translational motion. For small radii the detection processes is mainly based on the canal signal whereas for large radii it is dominated by the otolith signal. For intermediate radii the reduction in threshold due to the sensory combination is largest compared to using only one of the two sensors. One additional participant suffered from occasional vertigo after an ear infection indicating vestibular problems. She showed unusually high thresholds for translational motions, but normal thresholds for head-centered rotations. Interestingly, her thresholds for eccentric rotations were higher than her threshold for the head-centered rotations suggesting that she did not only use the rotational signal, but instead had a problem integrating the two sensory signals. These findings indicate that signals from the otolith and the semi-circular canals are not used independently, but are integrated in order to solve a direction detection task. no notspecified http://www.kyb.tuebingen.mpg.de/ published -42 15017 15422 SoykadBGB2011 7 F Soyka K de Winkel M Barnett-Cowan E Groen HH Bülthoff Fukuoka, Japan2011-10-00 855 12th International Multisensory Research Forum (IMRF 2011) Do humans integrate visual and vestibular information in a statistically optimal fashion when discriminating rotational self-motion stimuli? Recent studies are inconclusive as to whether such integration occurs when discriminating heading direction. In the present study eight participants were consecutively rotated twice (2s sinusoidal acceleration) on a chair about an earth-vertical axis in vestibular-only, visual-only and visual-vestibular trials. The visual stimulus was a video of a moving stripe pattern, synchronized with the inertial motion. Peak acceleration of the reference stimulus was varied and participants reported which rotation was perceived as faster. Just-noticeable differences (JND) were estimated by fitting psychometric functions. The visual-vestibular JND measurements are too high compared to the predictions based on the unimodal JND estimates and there is no JND reduction between visual-vestibular and visual-alone estimates. These findings may be explained by visual capture. Alternatively, the visual precision may not be equal between visual-vestibular and visual-alone conditions, since it has been shown that visual motion sensitivity is reduced during inertial self-motion. Therefore, measuring visual-alone JNDs with an underlying uncorrelated inertial motion might yield higher visual-alone JNDs compared to the stationary measurement. Theoretical calculations show that higher visual-alone JNDs would result in predictions consistent with the JND measurements for the visual-vestibular condition. no notspecified http://www.kyb.tuebingen.mpg.de/ published -855 15017 15422 deWinkelSBGB2011 7 K de Winkel F Soyka M Barnett-Cowan E Groen HH Bülthoff Toulouse, France2011-09-00 183 34th European Conference on Visual Perception Numerous studies report that humans integrate multisensory information in a statistically optimal fashion. However, with respect to self-motion perception, results are inconclusive. Here we test the hypothesis that visual and inertial cues in simulator environments are optimally integrated and that this integration develops over time. Eight participants performed a 2AFC discrimination experiment in visual-only, inertial-only and visual-inertial conditions. Conditions were repeated three times. Inertial motion stimuli were one-period 0.5 Hz sinusoidal acceleration profiles. Visual stimuli were videos of a vertical stripe pattern synchronized with inertial motion. Stimuli were presented in pairs with different peak velocity amplitudes. Participants judged which rotation of a pair had the highest velocity. Precision estimates were derived from psychometric functions. Optimal integration predicts improved precision in the combined condition. However, precision did not differ between the visual and combined conditions. This suggests that participants based their responses predominantly on visual motion. Alternatively, the results could be consistent with optimal integration if the assumption that visual precision remains unchanged during inertial motion was violated. We suggest that a change in visual sensitivity should be considered when investigating optimal integration of visual and inertial cues. no notspecified http://www.kyb.tuebingen.mpg.de/ published -183 15017 15422 diLucaMBE2011 7 M Di Luca T Machulla M Barnett-Cowan MO Ernst Tübingen, Germany2011-09-00 Bernstein Cluster D Symposium: Multisensory Perception and Action no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 15017 1542215017 18824 6404 7 M Barnett-Cowan MO Ernst HH Bülthoff Lausanne, Switzerland2010-08-00 146 33rd European Conference on Visual Perception In environments where orientation is ambiguous, the visual system uses prior knowledge about lighting coming from above to recognize objects, reorient the body, and determine which way is up (where is the sun?). It has been shown that when observers are tilted to the side relative to gravity, the orientation of the light-from-above prior will change in a direction between the orientation of the body, gravity and the visual surround. The contribution of ocular torsion in this change of the light-from-above prior has been acknowledged but not specifically addressed. Here we test the hypothesis that when lighting direction is the only available visual orientation cue, change in orientation of the light-from-above prior is accounted for by ocular torsion. Observers made convex-concave judgments of a central shaded disk, flanked by three similarly- and three oppositely-shaded disks. Lighting was tested every 15° in roll in the fronto-parallel plane. Observers were tested when upright, supine, and tilted every 30 ° in role relative to gravity. Our results show that change of the light-from-above prior is well predicted from a sum of two sines; one consistent with predicted ocular torsion, the other consistent with an additional component varying with twice the frequency of body tilt. no notspecified http://www.kyb.tuebingen.mpg.de/ published -146 15017 1542215017 18824 6508 7 M Barnett-Cowan T Meilinger M Vidal HH Bülthoff Reykjavik, Iceland2010-08-00 282 XXVI Bárány Society Meeting Path integration, the ability to update the position and orientation of external locations predominantly on the basis of internal cues, is an effective strategy for spatial navigation. While extensive work has been done on evaluating path integration in the horizontal plane, little is known for movements in the vertical (third) dimension. Here we assess whether pointing to the origin of translational movement in vertical planes is similar to that found for movement in the horizontal plane alone. 15 observers sat upright in a racecar seat that was mounted to the flange of a modified KUKA c anthropomorphic robot arm (Fig. 1a). An LCD display was 50cm in front of the observers who were otherwise tested in the dark. Sensory information was manipulated by providing visual (optic flow, limited lifetime star field), vestibular-kinesthetic (passive self motion with eyes closed), or visual and vestibularkinesthetic motion cues. Movement trajectories consisted of two segment lengths (1st: 0.4 m, 2 nd: 1 m; ± 0.24 m/s2 peak acceleration). Movements in the horizontal, sagittal and frontal planes consisted of: forward-rightward (FR) or rightward-forward (RF), downward-forward (DF) or forward-downward (FD), and downward-rightward (DR) or rightward-downward (RD) movements respectively. The angle of the two segments was either 45◦ or 90◦. A 15 s pause preceded each trajectory. Observers pointed back to their origin by moving an arrow that was superimposed on an avatar presented on the screen (Fig. 1b). Movement of the arrow was constrained to the trajectory’s plane and controlled by a joystick. The avatarwas presented from frontal, sagittal and horizontal viewpoints. Observers were allowed to use any or all viewpoints to answer. The starting orientation of the arrow was randomized across trials. Each condition was repeated 3 times and presented in random order. Signed error and response time were analyzed as dependent variables. Observers were more likely to underestimate angle size (average data less than 0◦; Fig. 1c) for movement in the horizontal plane compared to the vertical planes. In the frontal plane observers were more likely on average to overestimate angle size (average data more than 0◦), while there was no such bias in the sagittal plane. Another discrepancy between horizontal and vertical planes was that responses in the vertical planes were more closely related to a response bias suggesting that the path segments were of equal length (solid grey line). Finally, observers responded slower (Fig. 1d) when answering based on vestibular-kinesthetic information alone. These results suggest that human path integration based on vestibular-kinesthetic information alone takes longer than when visual information is present. Path integration has been well established as a means used to resolve where an observer originated but is prone to underestimates of the angle one has moved through. Our results show this for translational movement but only within the horizontal plane. In the vertical planes pointing may have been directed in accordance with an assumption of equal path lengths. This result suggests that alternative strategies for determining one’s origin may be adopted when moving in the third dimension which may relate to the fact that humans experience movement mostly within the horizontal plane. no notspecified http://www.kyb.tuebingen.mpg.de/ published -282 15017 15422 6419 7 M Di Luca M Barnett-Cowan Lausanne, Switzerland2010-08-00 187 33rd European Conference on Visual Perception Prolonged exposure to asynchronous audiovisual stimulus pairs changes the perception of audiovisual simultaneity. It has been proposed that this change occurs by adjusting the perceptual latency of stimuli in order to minimize perceived audiovisual asynchrony. How is this adjustment achieved? For signals with a gradual onset, perceptual latency can be minimized by decreasing detection threshold (or vice-versa). Here we assess whether this occurs following recalibration of simultaneity. Participants were exposed for 5 minutes to asynchronous (150ms) audiovisual stimulus pairs with either light or sound leading. Auditory stimuli were presented via headphones, visual via an LED. Detection thresholds for visual and auditory stimuli were then measured with a 2IFC task interleaved with short re-exposures to the asynchrony. Results indicate that while the detection threshold for visual stimuli does not significantly vary, the detection threshold for auditory stimuli critically depends on which modality leads during asynchronous audiovisual exposure. All nine participants tested were more sensitive in detecting auditory stimuli after light-leading exposure than after sound-leading. We suggest that by becoming more or less sensitive to sound the brain is able to change the perceptual latency of auditory stimuli to minimize audiovisual asynchrony, while keeping the perceptual latency of visual stimuli relatively constant. no notspecified http://www.kyb.tuebingen.mpg.de/ published -187 15017 1542215017 18824 6421 7 M Barnett-Cowan MO Ernst HH Bülthoff Liverpool, UK2010-06-00 11th International Multisensory Research Forum (IMRF 2010) In environments where orientation is ambiguous, the visual system uses prior knowledge about lighting coming from above to recognize objects, reorient the body, and determine which way is up (where is the sun?). It has been shown that when observers are tilted to the side relative to gravity, the orientation of the light-from-above prior will change in a direction between the orientation of the body, gravity and the visual surround. The contribution of ocular torsion in this change of the light-from-above prior has been acknowledged but not specifically addressed. Here we test the hypothesis that when lighting direction is the only available visual orientation cue, change in orientation of the light-from-above prior is accounted for by ocular torsion. Observers made convex-concave judgments of a central shaded disk, flanked by three similarly- and three oppositely-shaded disks. Lighting was tested every 15° in roll in the fronto-parallel plane. Observers were tested when upright, supine, and tilted every 30 ° in role relative to gravity. Our results show that change of the light-from-above prior is well predicted from a sum of two sines; one consistent with predicted ocular torsion, the other consistent with an additional component varying with twice the frequency of body tilt. no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 15017 1542215017 18824 6420 7 M Barnett-Cowan H Nolan JS Butler JJ Foxe RB Reilly HH Bülthoff Liverpool, UK2010-06-00 11th International Multisensory Research Forum (IMRF 2010) Involuntary physical responses to vestibular stimulation are very fast. The vestibulo-ocular reflex, for example, occurs approximately 20ms after the onset of vestibular stimulation (Lorente de No, 1933, Arch Neurol Psychiat). Despite these fast responses, reaction time (RT) to the perceived onset of vestibular stimulation occurs as late as 438ms after galvanic vestibular stimulation, which is approximately 220ms later than RTs to visual, somatosensory and auditory stimuli (Barnett-Cowan & Harris, 2009, Exp Brain Res). To determine whether RTs to natural vestibular stimulation are also slow, participants in the present study were passively moved forwards by .1178m (single cycle sinusoidal acceleration; 0.75m/s/s peak acceleration) using a Stewart motion platform and were asked to press a button relative to the onset of physical motion. RTs to auditory and visual stimuli were also collected. RTs to physical motion occurred significantly later (>100ms) than RTs to auditory and visual stimuli. Event related potentials (ERPs) were simultaneously recorded where the onset of the vestibular-ERP in both RT and non-RT trials occurred about 200ms or more after stimulus onset while the onset of the auditory- and visual-ERPs occurred less than 100ms after stimulus onset. All stimuli ERPs occurred approximately 135ms prior to RTs. These results provide further evidence that vestibular perception is slow compared to the other senses and that this perceptual latency may be related to latent cortical responses to physical motion. no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 15017 15422 6422 7 M Barnett-Cowan RW Fleming HH Bülthoff Liverpool, UK2010-06-00 113 11th International Multisensory Research Forum (IMRF 2010) Knowing an object's physical stability affects our expectations about its behaviour and our interactions with it. Objects topple over when the gravity-projected centre-of-mass (COM) lies outside the support area. The critical angle (CA) is the orientation for which an object is perceived to be equally likely to topple over or right itself, which is influenced by global shape information about an object's COM and its orientation relative to gravity. When observers lie on their sides, the perceived direction of gravity is tilted towards the body. Here we test the hypothesis that the CA of falling objects is affected by this internal representation of gravity. Observers sat upright or lay left- or right-side-down, and observed images of objects with different 3D mass distributions that were placed close to the right edge of a table in various orientations. Observers indicated whether the objects were more likely to fall back onto or off the table. The subjective visual vertical was also tested as a measure of perceived gravity. Our results show the CA increases when lying right-side-down and decreases when left-side-down relative to an upright posture, consistent with estimating the stability of rightward falling objects as relative to perceived and not physical gravity. no notspecified http://www.kyb.tuebingen.mpg.de/ published -113 15017 15422 6661 7 M Barnett-Cowan RT Dyde SH Fox E Moro WD Hutchison LR Harris Liverpool, UK2010-06-00 11th International Multisensory Research Forum (IMRF 2010) Perception of the relative orientation of the self, and objects in the environment, requires integration of visual and vestibular sensory information, and an internal representation of the body's orientation. Here I present and discuss findings on the relative contribution of these cues for orientation perception in Parkinson’s disease (PD; Barnett-Cowan et al., Neuroscience, In Press). The orientation of a line relative to vertical (i.e., subjective visual vertical) and the orientation in which a letter character is perceived as the ‘right way up’ (i.e., the perceptual upright) were measured in PD patients (on- and off-medication) and age-matched controls. Visual, vestibular and body cues were manipulated using a polarized visual room presented in various orientations while observers were upright or lying right-side-down. Patients were more influenced by vision than controls but only when setting a line to vertical. Patients relied less on the internal representation of the body when identifying characters as indicated by a greater influence of vestibular information. Consistent with reports of impaired proprioception among medicated PD patients, our effects were significant only when patients were medicated. I will discuss these results within a framework suggesting that this ‘impaired’ internal representation of the body may reflect physiological impairments in PD. no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 15017 15422 6212 7 M Barnett-Cowan H Nolan JS Butler JJ Foxe RB Reilly HH Bülthoff Naples, FL, USA2010-05-00 1400 10th Annual Meeting of the Vision Sciences Society (VSS 2010) Involuntary physical responses to vestibular stimulation are very fast. The vestibulo-ocular reflex, for example, occurs approximately 20ms after the onset of vestibular stimulation (Lorente de No, 1933, Arch Neurol Psychiat). Despite these fast responses, reaction time (RT) to the perceived onset of vestibular stimulation occurs as late as 438ms after galvanic vestibular stimulation, which is approximately 220ms later than RTs to visual, somatosensory and auditory stimuli (Barnett-Cowan & Harris, 2009, Exp Brain Res). To determine whether RTs to natural vestibular stimulation are also slow, participants in the present study were passively moved forwards by .1178m (single cycle sinusoidal acceleration; 0.75m/s/s peak acceleration) using a Stewart motion platform and were asked to press a button relative to the onset of physical motion. RTs to auditory and visual stimuli were also collected. RTs to physical motion occurred significantly later (>100ms) than RTs to auditory and visual stimuli. Event related potentials (ERPs) were simultaneously recorded where the onset of the vestibular-ERP in both RT and non-RT trials occurred about 200ms or more after stimulus onset while the onset of the auditory- and visual-ERPs occurred less than 100ms after stimulus onset. All stimuli ERPs occurred approximately 135ms prior to RTs. These results provide further evidence that vestibular perception is slow compared to the other senses and that this perceptual latency may be related to latent cortical responses to physical motion. no notspecified http://www.kyb.tuebingen.mpg.de/ published -1400 15017 15422 6025 7 ML Cadieux M Barnett-Cowan DI Shore New York, NY, USA2009-07-00 175 10th International Multisensory Research Forum (IMRF 2009) Participants judged which of two vibrotactile stimuli presented to the index fingers or thumbs occurred first. Past research has shown performance on this vibrotactile temporal order judgment (TOJ) task was more accurate when the hands were kept in their respective hemispaces, compared to when the hands were crossed over the midline. We examined the role of vision in this crossed-hands TOJ deficit by implementing three different visual conditions: eyes open with the lights on, eyes open with the lights off, and eyes closed with the lights off. No differences were seen. However, upon closer examination of the data, a significant effect of gender was found, such that male participants showed a smaller crossed-hands deficit than female participants. This overall difference was seen in the context of large individual differences. no notspecified http://www.kyb.tuebingen.mpg.de/ published -175 6026 7 M Barnett-Cowan LR Harris New York, NY, USA2009-07-00 270 10th International Multisensory Research Forum (IMRF 2009) In contrast to other senses, the latency of vestibular sensation has not been well investigated. We therefore measured the perceived timing of vestibular sensation relative to visual, tactile and auditory stimuli. Three types of vestibular stimulation were used: galvanic vestibular stimulation (GVS), passive head movements (HMp) and active head movements (HMa). Temporal order (TOJ) and simultaneity judgments (SJ) and reaction times (RTs) were made relative to full-field flashes, 50ms bursts of white noise, or of vibration of the finger tip. TOJs and SJs between vestibular and other sensory stimuli required the vestibular stimulus to occur ~160ms before other sensory stimuli for GVS (Fig. 1a), ~50ms before for HMp (Fig. 1b) and ~80ms before for HMa (Fig. 1c) in order for the pairs to be perceived as simultaneous. RTs to GVS-induced illusory head movement (438ms) were significantly longer than RTs to touch (245ms), light (220ms) or sound (197ms) (Fig. 1d) but not by enough to predict the TOJ and SJ results (Fig. 1e). The largely uncompensated lag in vestibular sensation probably reflects the fact that the vestibular system rarely works alone. The short latency eye and balance motor responses traditionally associated with the vestibular system are divorced from the perceptual correlates. no notspecified http://www.kyb.tuebingen.mpg.de/ published -270 6023 7 M Cadieux M Barnett-Cowan DI Shore Eilat, Israel2008-12-00 17th Annual Meeting of The Israel Society for Neuroscience no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 6022 7 M Barnett-Cowan LR Harris Hamburg, Germany2008-07-00 168 9th International Multisensory Research Forum (IMRF 2008) Different senses have different processing times. The consequences of this have been explored in the perceived timing of visual, auditory and tactile stimuli. However the perceived timing of vestibular stimulation, one of the fastest senses to be transduced, has not been systematically investigated. We measured the perceived timing of vestibular stimulation induced passively (head rotated by experimenter in response to ‘go’ stimulus) or under active control (head moved by participant in response to go stimulus). Visual, auditory and tactile stimuli were delivered at various delays from the go stimulus. Participants judged, in separate runs, whether the onset of head movement was simultaneous with the other stimulus (synchronicity judgements) or which stimulus came first (temporal order judgements). Most comparisons required head movements to occur first by between 50-90ms to be perceived as simultaneous, implying that head movements, both passive and active, were perceived after a longer latency than visual, auditory or tactile stimuli. Active movements generally needed a longer lead than passive, suggesting that they had the longest latency, which is consistent with vestibular sensitivity being reduced during active movement. These results will be discussed in terms of the perceived timing of active and passive head movement. no notspecified http://www.kyb.tuebingen.mpg.de/ published -168 6021 7 DY Balaban M Barnett-Cowan J Sanderson LR Harris Naples, FL, USA2008-06-00 1064 8th Annual Meeting of the Vision Sciences Society (VSS 2008) Both physical body roll and illusory roll evoked by full-field visual motion induce changes in blood pressure (BP) (Aoki et al. 2000 Clin. Aut. Res. 10: 23). How do these BP responses combine when both vestibular and visual information concerning roll are present? Subjects sat in a padded chair inside a 9ft diameter sphere, the inside surface of which was covered in high-contrast random dots. The chair and sphere could be independently rotated about the subjects' roll axis. Subjects were physically rolled clockwise from upright to right-ear-down at 7.6°/s, which took 12s. The sphere was rotated either alone, or so as to enhance (counter clockwise), oppose (clockwise), or null (clockwise at 7.6°/s) simultaneous physical roll. BP was continuously monitored by a finger plethysmograph throughout the movement and for several seconds following. Verbal reports of perceived body orientation were noted. BP typically increased from baseline levels during physical roll in the dark and the increase was maintained while subjects remained right-ear-down. The BP response to visually evoked roll was a transient increase reaching a peak at ∼6s. The BP changes in response to combinations of physical and visual roll were well described by a weighted linear sum of the responses to physical and visual motion presented separately even when the sphere remained earth stationary (the natural cue combination). The magnitude of perceived roll reported was accurate during roll in the dark and was systematically modulated by visual motion. These BP changes suggest that the autonomic responses to combinations of visual and vestibular cues reflect integration of information from the two systems. no notspecified http://www.kyb.tuebingen.mpg.de/ published -1064 6020 7 H Jenkin M Barnett-Cowan RT Dyde J Sanderson M Jenkin L Harris Naples, FL, USA2008-06-00 1062 8th Annual Meeting of the Vision Sciences Society (VSS 2008) INTRODUCTION The direction of the orientation at which objects and characters are most easily recognized, the perceived upright has been modelled as a weighted vector sum of the directions defined by the body's long axis (egocentric), gravity, and visible cues (Dyde et al. 2006, Exp. Brain Res.). This model predicts symmetrical responses such that subjects lying left or right side down relative to gravity should exhibit mirror symmetric patterns of responses. Such symmetry is also expected if torsional eye orientation dependent upon body orientation relative to gravity or visual orientation relative to the body is included in the model. METHODS Nineteen subjects drawn from researchers and students at York University participated. The Oriented Character Recognition Test (OCHART - described in Dyde et al. 2006) was administered while subjects viewed several orientations of visual background while either upright, left side down, or right side down relative to gravity. OCHART identifies the perceptual upright using the perceived identity of letters. RESULTS Responses revealed a systematic difference between the response pattern when lying left side down and lying right side down. This asymmetry can be modelled by a leftwise bias in the perceived orientation of the body relative to its actual orientation. DISCUSSION The asymmetry in the effect of body orientation is reminiscent of the left-leaning asymmetry in determining the direction of light coming from above (Mamassian & Goutcher 2001 Cognition 81:B1). The asymmetry might reflect a similar tendency to perceive the body as tilted. no notspecified http://www.kyb.tuebingen.mpg.de/ published -1062 6019 7 M Barnett-Cowan J Sanderson RT Dyde SH Fox WD Hutchison LR Harris San Diego, CA, USA2007-11-00 37th Annual Meeting of the Society for Neuroscience (Neuroscience 2007) Previous reports have suggested that patients with Parkinson’s disease (PD) have increased visual dominance for spatial perception tasks. We therefore assessed the relative roles of visual and non-visual cues in determining the subjective visual vertical (SVV) and the perceptual upright (PU) in patients with PD using a luminous line and the newly developed OCHART test (Exp. Brain. Res. 173; 612-622). Visual cues were manipulated by filling the visual field with a static 2D image containing either a frame (tilted ± 18º) or polarized room (tilted ±18º and ± 112.5º). Images were viewed on a laptop through a circular shroud (diameter: 42º). The SVV was measured by asking whether a line was tilted left or right of vertical. The PU was measured by identifying a character whose identity depended on its orientation and locating its most ambiguous orientations. To measure the relative contributions of visual, vestibular and body orientation cues, cues were separated by testing while upright or lying right side down. Patients with PD were tested on and off (12 hour washout) of their medications and compared to an age-matched control group. No differences were found attributable to medication. Patients with PD had a significantly higher variance for both the SVV and PU tasks compared to controls. When upright, patients with PD were more influenced by visual cues than controls for the SVV task. However, when tested lying on their sides, the control group was more influenced by visual cues for the SVV task. When both body orientations were taken together patients with PD were found to be more influenced by body orientation than visual cues for the SVV task. The PU in patients with PD was also found to be less influenced by visual cues than controls. This pattern of results suggests that PU and SVV may be determined by different mechanisms, with only the SVV showing an increased visual dependence in PD and then only when upright. We conclude that across different body postures, patients with PD are more influenced by the orientation of their body than visual cues in spatial perception tasks, that is, in general the body’s orientation is more heavily weighted in patients with PD than in age-matched controls. no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 6017 7 H Jenkin M Barnett-Cowan A Islam E Mazour J Sanderson RT Dyde MR Jenkin LR Harris Arezzo, Italy2007-08-00 208 30th European Conference on Visual Perception The perceptual upright (PU), the orientation in which an object is most easily and naturally recognized, is determined by combining visual, gravity, and body cues. Recognizing a character the identity of which depends on its orientation can be used to assess PU. For example, the letter 'p' when rotated 180° becomes the letter 'd'. The transitions from p to d and d to p, when averaged, define PU. This is the orientated character recognition task (OCHART). The PU can be predicted from the weighted vector sum of the orientation of the visual background, gravity, and body. Observers completed OCHART in several body tilts in roll. The PU measured at some body tilts (eg 45°) was not accurately predicted by this simple model. One possible explanation for this is that the nervous system's assessment of the relative weights and directions of vision, gravity, and the body required to determine the PU may depend on the internal representation of the body tilt and the orientation of the eyes in the head. no notspecified http://www.kyb.tuebingen.mpg.de/ published -208 6018 7 M Barnett-Cowan C Thompson J Sanderson RT Dyde LR Harris Arezzo, Italy2007-08-00 206 207 30th European Conference on Visual Perception Previous reports suggest differences between males and females when performing spatial perception tasks, where males align a luminous line more accurately with gravity. This may be attributable to males and females weighting visual, gravity, and body orientation cues differently. The subjective visual vertical (SVV) and the perceptual upright (PU) were assessed with different visual and body orientations. SVV was measured by using the luminous line. PU was measured with the orientated-character-recognition task (OCHART). For SVV, when upright, females were significantly more influenced by visual cues and had higher variances than males. When lying sideways males and females were equally influenced by vision and had equal variances. For PU, males and females were equally influenced by visual cues and had equal variances at both body orientations. These differences confirm that PU and SVV are determined by different mechanisms with only the SVV showing gender differences. no notspecified http://www.kyb.tuebingen.mpg.de/ published 1 6016 7 M Barnett-Cowan J Sanderson RT Dyde LR Harris 2007-00-00 Toronto, Canada I Annual meeting of the Canadian Association for Neuroscience no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 6015 7 RT Dyde M Barnett-Cowan C Thompson J Sanderson LR Harris 2007-00-00 Toronto, Canada Centre for Vision Research 2007 Conference no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 6014 7 M Barnett-Cowan J Sanderson RT Dyde LR Harris 2007-00-00 Toronto, Canada Centre for Vision Research 2007 Conference no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 6013 7 M Barnett-Cowan LR Harris 2006-00-00 Dublin, Ireland VII Annual Meeting of the International Multisensory Research Forum no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 6012 7 M Barnett-Cowan LR Harris 2005-00-00 Toronto, Canada Centre for Vision Research 2005 Conference no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 6011 7 M Barnett-Cowan M Peters 2003-00-00 XVI Annual Meeting of Theoretical and Experimental Neuropsychology, Montreal, Canada no notspecified http://www.kyb.tuebingen.mpg.de/ published 0 6004 15 M Barnett-Cowan 2009-05-00 no notspecified published 6003 14 M Barnett-Cowan 2005-06-00 no notspecified published diplom 6002 14 M Barnett-Cowan 2002-05-00 no notspecified published diplom BarnettCowan2012 10 M Barnett-Cowan SoykaBRB2012 10 F Soyka M Barnett Cowan P Robuffo Giordano HH Bülthoff BarnettCowanCS2012 10 M Barnett-Cowan JC Culham JC Snow SoykaBRB2012_2 10 F Soyka M Barnett-Cowan P Robuffo Giordano HH Bülthoff 6405 10 RW Fleming M Barnett-Cowan HH Bülthoff 6407 10 M Barnett-Cowan 6006 10 M Barnett-Cowan 6005 10 M Barnett-Cowan 6010 10 M Barnett-Cowan LR Harris 6009 10 M Barnett-Cowan RT Dyde LR Harris 6008 10 M Barnett-Cowan RT Dyde LR Harris 6007 10 M Barnett-Cowan