280 research outputs found
Data For: Heading Through A Crowd
No full textData and analysis scripts to accompany the article "Heading Through A Crowd" by Dr. Hugh Riddell and Prof. Dr. Markus Lappe. All analysis scripts are in SPSS format. Data has been provided in SPSS and .txt formats. Any correspondence should be addressed to Prof. Dr. Markus Lappe.</p
LappeOpenPracticesDisclosure – Supplemental material for Heading Through a Crowd
No full textSupplemental material, LappeOpenPracticesDisclosure for Heading Through a Crowd by Hugh Riddell and Markus Lappe in Psychological Science</p
LappeFigureS1 – Supplemental material for Heading Through a Crowd
No full textSupplemental material, LappeFigureS1 for Heading Through a Crowd by Hugh Riddell and Markus Lappe in Psychological Science</p
Images used in the study: "Salient objects dominate the central fixation bias when orienting towards images"
No full textImage files used in the study "Salient objects dominate the central fixation bias when orienting towards images" by Christian Wolf and Markus Lappe. Each of the two zip files contains image files (*.jpg) used for the two experiments.
For questions please contact chr.wolf[at]wwu.d
Comparing the influence of stimulus size and contrast on the perception of moving gratings and random dot patterns—A registered report protocol
No full textModern accounts of visual motion processing in the primate brain emphasize a hierarchy of different regions within the dorsal visual pathway, especially primary visual cortex (V1) and the middle temporal area (MT). However, recent studies have called the idea of a processing pipeline with fixed contributions to motion perception from each area into doubt. Instead, the role that each area plays appears to depend on properties of the stimulus as well as perceptual history. We propose to test this hypothesis in human subjects by comparing motion perception of two commonly used stimulus types: drifting sinusoidal gratings (DSGs) and random dot patterns (RDPs). To avoid potential biases in our approach we are pre-registering our study. We will compare the effects of size and contrast levels on the perception of the direction of motion for DSGs and RDPs. In addition, based on intriguing results in a pilot study, we will also explore the effects of a post-stimulus mask. Our approach will offer valuable insights into how motion is processed by the visual system and guide further behavioral and neurophysiological research.Modern accounts of visual motion processing in the primate brain emphasize a hierarchy of different regions within the dorsal visual pathway, especially primary visual cortex (V1) and the middle temporal area (MT). However, recent studies have called the idea of a processing pipeline with fixed contributions to motion perception from each area into doubt. Instead, the role that each area plays appears to depend on properties of the stimulus as well as perceptual history. We propose to test this hypothesis in human subjects by comparing motion perception of two commonly used stimulus types: drifting sinusoidal gratings (DSGs) and random dot patterns (RDPs). To avoid potential biases in our approach we are pre-registering our study. We will compare the effects of size and contrast levels on the perception of the direction of motion for DSGs and RDPs. In addition, based on intriguing results in a pilot study, we will also explore the effects of a post-stimulus mask. Our approach will offer valuable insights into how motion is processed by the visual system and guide further behavioral and neurophysiological research
Anna Lappe, Small Planet Institute
No full textIf you are like me…50-something or even more chronologically gifted, you remember Frances Moore-Lappe’s book Diet for a Small Planet. Nothing short of revolutionary — for so many people it was life changing, many people converting to vegetarianism virtually overnight. When I heard that Frances’ daughter Anna was coming to town to be the keynote speaker at the Food Summit, sponsored by the Food Policy Council, I knew this was my opportunity to have a conversation with her. Anna is the author of many books and travels throughout the world speaking about food security and sovereignty. Through the great work of May Patino at the California Center for Rural Policy, located at Humboldt State University, it happened!
But you know how it is — so many questions and only 10 minutes for an interview — so of course I asked what it was like at the dinner table growing up with Frances Moore-Lappe
Adaptation of saccades and perceived size after trans-saccadic changes of object size
No full textWhen saccadic eye movements consistently fail to land on the intended target, saccade accuracy is maintained by gradually adapting the amplitude of successive saccades to the same target. Such saccadic adaptation is usually induced by systematically displacing a small visual target during the execution of the saccade. However, saccades are normally performed to extended objects. Here we report changes in saccade amplitude when the size of a target object is systematically changed during a saccade. Moreover, we find that this manipulation also affected the visual perception of the size of that object. Human subjects were tested in shortening and lengthening adaptation where they had to make saccades to targets of different sizes, which were each shortened or lengthened during saccade execution, respectively. In both experiments, a preadaptation and postadaptation phase required manually indicating the horizontal size of each target by grip aperture and, in a further experiment, a verbal size report. We evaluated the effect of change in visual perception on saccade and on the two modalities of judgment. We observed that (1) saccadic adaptation can be induced by modifying target object size and (2) this gradual change in saccade amplitude in the direction of the object size change evokes a concomitant change in perceived object size. These findings suggest that size is a relevant signal for saccadic system and its trans-saccadic manipulation entails considerable changes at multiple levels of sensorimotor performance
Estimation of Travel Distance from Visual Motion in Virtual Environments
No full textDistance estimation of visually simulated self-motion is difficult, because one has to know or make assumptions about scene layout to judge ego speed. Discrimination of the travel distances of two sequentially simulated self-motions in the same scene can be performed quite accurately (Bremmer and Lappe 1999; Frenz et al., 2003). However, the indication of the perceived distance of a single movement in terms of a spatial interval results in a depth scaling error: Intervals are correlated with the true travel distance, but underestimate travel distance by about 25 % (Frenz and Lappe, 2005). Here we investigated whether the inclusion of further depth cues (disparity/motion parallax/figural cues) in the virtual environment allows more veridical interval adjustment. Experiments were conducted on a large single projection screen and in a fully immersive computer-animated virtual environment (CAVE). Forward movements in simple virtual environments were simulated with distances between 1.5 and 13 m with varying speeds. Subjects indicated the perceived distance of each movement in terms of a depth interval on the virtual ground plane. We found good correlation between simulated and indicated distances, indicative of an internal representation of the perceived distance. The slopes of the fitted regression lines revealed an underestimation of distance by about 25 % under all conditions. We conclude that estimation of travel distance from optic flow is subject to scaling when compared to static intervals in th
Optokinetic Eye Movements Elicited by Radial Optic Flow in the Macaque Monkey
No full text Lappe, Markus, Martin Pekel, and Klaus-Peter Hoffmann. Optokinetic eye movements elicited by radial optic flow in the macaque monkey. J. Neurophysiol. 79: 1461–1480, 1998. We recorded spontaneous eye movements elicited by radial optic flow in three macaque monkeys using the scleral search coil technique. Computer-generated stimuli simulated forward or backward motion of the monkey with respect to a number of small illuminated dots arranged on a virtual ground plane. We wanted to see whether optokinetic eye movements are induced by radial optic flow stimuli that simulate self-movement, quantify their parameters, and consider their effects on the processing of optic flow. A regular pattern of interchanging fast and slow eye movements with a frequency of 2 Hz was observed. When we shifted the horizontal position of the focus of expansion (FOE) during simulated forward motion (expansional optic flow), median horizontal eye position also shifted in the same direction but only by a smaller amount; for simulated backward motion (contractional optic flow), median eye position shifted in the opposite direction. We relate this to a change in Schlagfeld typically observed in optokinetic nystagmus. Direction and speed of slow phase eye movements were compared with the local flow field motion in gaze direction (the foveal flow). Eye movement direction matched well the foveal motion. Small systematic deviations could be attributed to an integration of the global motion pattern. Eye speed on average did not match foveal stimulus speed, as the median gain was only ∼0.5–0.6. The gain was always lower for expanding than for contracting stimuli. We analyzed the time course of the eye movement immediately after each saccade. We found remarkable differences in the initial development of gain and directional following for expansion and contraction. For expansion, directional following and gain were initially poor and strongly influenced by the ongoing eye movement before the saccade. This was not the case for contraction. These differences also can be linked to properties of the optokinetic system. We conclude that optokinetic eye movements can be elicited by radial optic flow fields simulating self-motion. These eye movements are linked to the parafoveal flow field, i.e., the motion in the direction of gaze. In the retinal projection of the optic flow, such eye movements superimpose retinal slip. This results in complex retinal motion patterns, especially because the gain of the eye movement is small and variable. This observation has special relevance for mechanisms that determine self-motion from retinal flow fields. It is necessary to consider the influence of eye movements in optic flow analysis, but our results suggest that direction and speed of an eye movement should be treated differently. </jats:p
dcnieho/ViveTestCodeData: V1.0.1
No full textThis repository contains code and data from the paper
Niehorster, D.C., Li, L. & Lappe, M. (2017). The accuracy and precision
of position and orientation tracking in the HTC Vive virtual reality
system for scientific research. i-Perception. DOI: 10.1177/2041669517708205
The code and data in this repository are licensed under the Creative
Commons Attribution 4.0 (CC BY 4.0) license. When using any of the
contents of this repository, with or without modification, please cite
Niehorster, D.C., Li, L. & Lappe, M. (2017). The accuracy and precision
of position and orientation tracking in the HTC Vive virtual reality
system for scientific research. i-Perception.
This repository is available from www.github.com/dcnieho/ViveTestCodeData
What's in the repository:
* acquisition: python/Vizard 5.6 scripts for recording data. Contains:
* testTracking - acquire data upon trigger pull, used for capturing data along grid
* testTrackingOcclusion - acquire data after intervening track loss. Used for recovery tests
* testTrackingLatency - show image until tracker position changed significantly. Used for latency test
* analysis: matlab scripts for analyzing data
* Figure 2: testTrackFaceOneWay
* Figure 3: testTrackFaceOneWay
* Figure 4: testTrackFaceBothWays
* Figure 5: rotationInternalConsistency
* Figure 6: testTrackFaceBothWays
* Figure 7: testTrackFaceBothWays
* Figure 8: testTrackRecovery
* Figure 9: testTrackRecovery
* Figure 10: testTrackRecovery
* Figure 11ab: testTrackFaceBothWays5m
* Figure 11c: testTrackRecovery
* Figure 12ab: testTrackFaceBothWays5m
* Figure 12c: testTrackRecovery
* Figure 13ab: testTrackFaceBothWays5m
* Figure 13c: testTrackRecovery
* data: folder with data files from the paper
Data disclaimer, limitations and conditions of release
By downloading this data set, you expressly agree to the following conditions of release and acknowledge the following disclaimers issued by the authors:
A. Conditions of Release
Data are available by permission of the authors. Use of data in publications, either digital or hardcopy, must be cited as follows:
Niehorster, D.C., Li, L. & Lappe, M. (2017). The accuracy and precision of position and orientation tracking in the HTC Vive virtual reality system for scientific research. i-Perception. doi: 10.1177/2041669517708205
B. Disclaimer of Liability
The authors shall not be held liable for any improper or incorrect use or application of the data provided, and assume no responsibility for the use or application of the data or interpretations based on the data, or information derived from interpretation of the data. In no event shall the authors be liable for any direct, indirect or incidental damage, injury, loss, harm, illness or other damage or injury arising from the release, use or application of these data. This disclaimer of liability applies to any direct, indirect, incidental, exemplary, special or consequential damages or injury, even if advised of the possibility of such damage or injury, including but not limited to those caused by any failure of performance, error, omission, defect, delay in operation or transmission, computer virus, alteration, use, application, analysis or interpretation of data.
C. Disclaimer of Accuracy of Data
No warranty, expressed or implied, is made regarding the accuracy, adequacy, completeness, reliability or usefulness of any data provided. These data are provided "as is." All warranties of any kind, expressed or implied, including but not limited to fitness for a particular use, freedom from computer viruses, the quality, accuracy or completeness of data or information, and that the use of such data or information will not infringe any patent, intellectual property or proprietary rights of any party, are disclaimed. The user expressly acknowledges that the data may contain some nonconformities, omissions, defects, or errors. The authors do not warrant that the data will meet the user’s needs or expectations, or that all nonconformities, omissions, defects, or errors can or will be corrected. The authors are not inviting reliance on these data, and the user should always verify actual data
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