Open Access Publications
From research on the visual systems of turtles, to the perception of faces with or without makeup, to transaccadic perception and perceptual cycles in the brain– VPixx hardware and software solutions have supported research in vision science and beyond for over 20 years. We are immensely proud of the discoveries and accomplishments of our customers across the world.
On this page you will find a non-exhaustive list of peer-reviewed, open access publications citing VPixx tools dating back to 2003. Browse the list or use the tag filter to search for specific products. Note that we report the device used in the paper according to the authors; this may not accurately reflect the specific model of device used (e.g., VIEWPixx vs. VIEWPixx /3D). Nor do we guarantee the accuracy of published content. Please contact our team at [email protected] if you have any questions about a specific paper.
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Use the search tool below to search for specific terms among the titles, authors and abstracts in our library.
241.
Ruhnau, Philipp; Keitel, Christian; Lithari, Chrysa; Weisz, Nathan; Neuling, Toralf
Flicker-Driven Responses in Visual Cortex Change during Matched-Frequency Transcranial Alternating Current Stimulation Journal Article
In: Frontiers in Human Neuroscience, vol. 10, 2016, ISSN: 1662-5161.
Abstract | Links | BibTeX | Tags: PROPixx
@article{ruhnau_flicker-driven_2016,
title = {Flicker-Driven Responses in Visual Cortex Change during Matched-Frequency Transcranial Alternating Current Stimulation},
author = {Philipp Ruhnau and Christian Keitel and Chrysa Lithari and Nathan Weisz and Toralf Neuling},
url = {https://www.frontiersin.org/articles/10.3389/fnhum.2016.00184},
issn = {1662-5161},
year = {2016},
date = {2016-01-01},
urldate = {2024-01-03},
journal = {Frontiers in Human Neuroscience},
volume = {10},
abstract = {We tested a novel combination of two neuro-stimulation techniques, transcranial alternating current stimulation (tACS) and frequency tagging, that promises powerful paradigms to study the causal role of rhythmic brain activity in perception and cognition. Participants viewed a stimulus flickering at 7 or 11 Hz that elicited periodic brain activity, termed steady-state responses (SSRs), at the same temporal frequency and its higher order harmonics. Further, they received simultaneous tACS at 7 or 11 Hz that either matched or differed from the flicker frequency. Sham tACS served as a control condition. Recent advances in reconstructing cortical sources of oscillatory activity allowed us to measure SSRs during concurrent tACS, which is known to impose strong artifacts in magnetoencephalographic (MEG) recordings. For the first time, we were thus able to demonstrate immediate effects of tACS on SSR-indexed early visual processing. Our data suggest that tACS effects are largely frequency-specific and reveal a characteristic pattern of differential influences on the harmonic constituents of SSRs.},
keywords = {PROPixx},
pubstate = {published},
tppubtype = {article}
}
We tested a novel combination of two neuro-stimulation techniques, transcranial alternating current stimulation (tACS) and frequency tagging, that promises powerful paradigms to study the causal role of rhythmic brain activity in perception and cognition. Participants viewed a stimulus flickering at 7 or 11 Hz that elicited periodic brain activity, termed steady-state responses (SSRs), at the same temporal frequency and its higher order harmonics. Further, they received simultaneous tACS at 7 or 11 Hz that either matched or differed from the flicker frequency. Sham tACS served as a control condition. Recent advances in reconstructing cortical sources of oscillatory activity allowed us to measure SSRs during concurrent tACS, which is known to impose strong artifacts in magnetoencephalographic (MEG) recordings. For the first time, we were thus able to demonstrate immediate effects of tACS on SSR-indexed early visual processing. Our data suggest that tACS effects are largely frequency-specific and reveal a characteristic pattern of differential influences on the harmonic constituents of SSRs.
242.
Wolf, Christian; Schütz, Alexander C.
Trans-saccadic integration of peripheral and foveal feature information is close to optimal Journal Article
In: Journal of Vision, vol. 15, no. 16, pp. 1, 2015, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: VIEWPixx
@article{wolf_trans-saccadic_2015,
title = {Trans-saccadic integration of peripheral and foveal feature information is close to optimal},
author = {Christian Wolf and Alexander C. Schütz},
url = {https://doi.org/10.1167/15.16.1},
doi = {10.1167/15.16.1},
issn = {1534-7362},
year = {2015},
date = {2015-12-01},
urldate = {2024-01-18},
journal = {Journal of Vision},
volume = {15},
number = {16},
pages = {1},
abstract = {Due to the inhomogenous visual representation across the visual field, humans use peripheral vision to select objects of interest and foveate them by saccadic eye movements for further scrutiny. Thus, there is usually peripheral information available before and foveal information after a saccade. In this study we investigated the integration of information across saccades. We measured reliabilities—i.e., the inverse of variance—separately in a presaccadic peripheral and a postsaccadic foveal orientation-discrimination task. From this, we predicted trans-saccadic performance and compared it to observed values. We show that the integration of incongruent peripheral and foveal information is biased according to their relative reliabilities and that the reliability of the trans-saccadic information equals the sum of the peripheral and foveal reliabilities. Both results are consistent with and indistinguishable from statistically optimal integration according to the maximum-likelihood principle. Additionally, we tracked the gathering of information around the time of the saccade with high temporal precision by using a reverse correlation method. Information gathering starts to decline between 100 and 50 ms before saccade onset and recovers immediately after saccade offset. Altogether, these findings show that the human visual system can effectively use peripheral and foveal information about object features and that visual perception does not simply correspond to disconnected snapshots during each fixation.},
keywords = {VIEWPixx},
pubstate = {published},
tppubtype = {article}
}
Due to the inhomogenous visual representation across the visual field, humans use peripheral vision to select objects of interest and foveate them by saccadic eye movements for further scrutiny. Thus, there is usually peripheral information available before and foveal information after a saccade. In this study we investigated the integration of information across saccades. We measured reliabilities—i.e., the inverse of variance—separately in a presaccadic peripheral and a postsaccadic foveal orientation-discrimination task. From this, we predicted trans-saccadic performance and compared it to observed values. We show that the integration of incongruent peripheral and foveal information is biased according to their relative reliabilities and that the reliability of the trans-saccadic information equals the sum of the peripheral and foveal reliabilities. Both results are consistent with and indistinguishable from statistically optimal integration according to the maximum-likelihood principle. Additionally, we tracked the gathering of information around the time of the saccade with high temporal precision by using a reverse correlation method. Information gathering starts to decline between 100 and 50 ms before saccade onset and recovers immediately after saccade offset. Altogether, these findings show that the human visual system can effectively use peripheral and foveal information about object features and that visual perception does not simply correspond to disconnected snapshots during each fixation.
243.
Chacón, José; Castellanos, Miguel Ángel; Serrano-Pedraza, Ignacio
Characterizing visual asymmetries in contrast perception using shaded stimuli Journal Article
In: Journal of Vision, vol. 15, no. 16, pp. 11, 2015, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: DATAPixx, RESPONSEPixx
@article{chacon_characterizing_2015,
title = {Characterizing visual asymmetries in contrast perception using shaded stimuli},
author = {José Chacón and Miguel Ángel Castellanos and Ignacio Serrano-Pedraza},
url = {https://doi.org/10.1167/15.16.11},
doi = {10.1167/15.16.11},
issn = {1534-7362},
year = {2015},
date = {2015-12-01},
urldate = {2023-12-22},
journal = {Journal of Vision},
volume = {15},
number = {16},
pages = {11},
abstract = {Previous research has shown a visual asymmetry in shaded stimuli where the perceived contrast depended on the polarity of their dark and light areas (Chacón, 2004). In particular, circles filled out with a top-dark luminance ramp were perceived with higher contrast than top-light ones although both types of stimuli had the same physical contrast. Here, using shaded stimuli, we conducted four experiments in order to find out if the perceived contrast depends on: (a) the contrast level, (b) the type of shading (continuous vs. discrete) and its degree of perceived three-dimensionality, (c) the orientation of the shading, and (d) the sign of the perceived contrast alterations. In all experiments the observers' tasks were to equate the perceived contrast of two sets of elements (usually shaded with opposite luminance polarity), in order to determine the subjective equality point. Results showed that (a) there is a strong difference in perceived contrast between circles filled out with luminance ramp top-dark and top-light that is similar for different contrast levels; (b) we also found asymmetries in contrast perception with different shaded stimuli, and this asymmetry was not related with the perceived three-dimensionality but with the type of shading, being greater for continuous-shading stimuli; (c) differences in perceived contrast varied with stimulus orientation, showing the maximum difference on vertical axis with a left bias consistent with the bias found in previous studies that used visual-search tasks; and (d) asymmetries are consistent with an attenuation in perceived contrast that is selective for top-light vertically-shaded stimuli.},
keywords = {DATAPixx, RESPONSEPixx},
pubstate = {published},
tppubtype = {article}
}
Previous research has shown a visual asymmetry in shaded stimuli where the perceived contrast depended on the polarity of their dark and light areas (Chacón, 2004). In particular, circles filled out with a top-dark luminance ramp were perceived with higher contrast than top-light ones although both types of stimuli had the same physical contrast. Here, using shaded stimuli, we conducted four experiments in order to find out if the perceived contrast depends on: (a) the contrast level, (b) the type of shading (continuous vs. discrete) and its degree of perceived three-dimensionality, (c) the orientation of the shading, and (d) the sign of the perceived contrast alterations. In all experiments the observers' tasks were to equate the perceived contrast of two sets of elements (usually shaded with opposite luminance polarity), in order to determine the subjective equality point. Results showed that (a) there is a strong difference in perceived contrast between circles filled out with luminance ramp top-dark and top-light that is similar for different contrast levels; (b) we also found asymmetries in contrast perception with different shaded stimuli, and this asymmetry was not related with the perceived three-dimensionality but with the type of shading, being greater for continuous-shading stimuli; (c) differences in perceived contrast varied with stimulus orientation, showing the maximum difference on vertical axis with a left bias consistent with the bias found in previous studies that used visual-search tasks; and (d) asymmetries are consistent with an attenuation in perceived contrast that is selective for top-light vertically-shaded stimuli.
244.
Mather, George; Sharman, Rebecca J.
Decision-level adaptation in motion perception Journal Article
In: Royal Society Open Science, vol. 2, no. 12, pp. 150418, 2015, (Publisher: Royal Society).
Abstract | Links | BibTeX | Tags: RESPONSEPixx, VIEWPixx3D
@article{mather_decision-level_2015,
title = {Decision-level adaptation in motion perception},
author = {George Mather and Rebecca J. Sharman},
url = {https://royalsocietypublishing.org/doi/10.1098/rsos.150418},
doi = {10.1098/rsos.150418},
year = {2015},
date = {2015-12-01},
urldate = {2024-01-02},
journal = {Royal Society Open Science},
volume = {2},
number = {12},
pages = {150418},
abstract = {Prolonged exposure to visual stimuli causes a bias in observers' responses to subsequent stimuli. Such adaptation-induced biases are usually explained in terms of changes in the relative activity of sensory neurons in the visual system which respond selectively to the properties of visual stimuli. However, the bias could also be due to a shift in the observer's criterion for selecting one response rather than the alternative; adaptation at the decision level of processing rather than the sensory level. We investigated whether adaptation to implied motion is best attributed to sensory-level or decision-level bias. Three experiments sought to isolate decision factors by changing the nature of the participants' task while keeping the sensory stimulus unchanged. Results showed that adaptation-induced bias in reported stimulus direction only occurred when the participants' task involved a directional judgement, and disappeared when adaptation was measured using a non-directional task (reporting where motion was present in the display, regardless of its direction). We conclude that adaptation to implied motion is due to decision-level bias, and that a propensity towards such biases may be widespread in sensory decision-making.},
note = {Publisher: Royal Society},
keywords = {RESPONSEPixx, VIEWPixx3D},
pubstate = {published},
tppubtype = {article}
}
Prolonged exposure to visual stimuli causes a bias in observers' responses to subsequent stimuli. Such adaptation-induced biases are usually explained in terms of changes in the relative activity of sensory neurons in the visual system which respond selectively to the properties of visual stimuli. However, the bias could also be due to a shift in the observer's criterion for selecting one response rather than the alternative; adaptation at the decision level of processing rather than the sensory level. We investigated whether adaptation to implied motion is best attributed to sensory-level or decision-level bias. Three experiments sought to isolate decision factors by changing the nature of the participants' task while keeping the sensory stimulus unchanged. Results showed that adaptation-induced bias in reported stimulus direction only occurred when the participants' task involved a directional judgement, and disappeared when adaptation was measured using a non-directional task (reporting where motion was present in the display, regardless of its direction). We conclude that adaptation to implied motion is due to decision-level bias, and that a propensity towards such biases may be widespread in sensory decision-making.
245.
Haines, Alice E.; Hornsey, Rebecca L.; Hibbard, Paul B.
Quality, quantity and precision of depth perception in stereoscopic displays Proceedings Article
In: 2015 International Conference on 3D Imaging (IC3D), pp. 1–6, IEEE, Liège, Belgium, 2015, ISBN: 978-1-5090-1265-7.
Abstract | Links | BibTeX | Tags: 3DPixx, RESPONSEPixx, VIEWPixx3D
@inproceedings{haines_quality_2015,
title = {Quality, quantity and precision of depth perception in stereoscopic displays},
author = {Alice E. Haines and Rebecca L. Hornsey and Paul B. Hibbard},
url = {http://ieeexplore.ieee.org/document/7391813/},
doi = {10.1109/IC3D.2015.7391813},
isbn = {978-1-5090-1265-7},
year = {2015},
date = {2015-12-01},
urldate = {2024-01-17},
booktitle = {2015 International Conference on 3D Imaging (IC3D)},
pages = {1–6},
publisher = {IEEE},
address = {Liège, Belgium},
abstract = {Stereoscopic 3D viewing (S3D) can create a clear and compelling improvement in the quality of the 3D experience compared with 2D displays. This improvement is distinct from any change in the amount of depth perceived, or the apparent 3D shapes of objects and the distances between them. It has been suggested instead that the enhanced feeling of realness is associated more with the precision with which we see depth. We measured the contribution of stereoscopic cues to the quality of depth perception in simple abstract images and complex natural scenes. We varied the amount of disparity present in the simple scenes in order to dissociate the magnitude and precision of perceived depth. We show that the qualitative enhancement of perceived depth in stereoscopic displays can be readily quantified, and that it is more closely related to the precision than to the magnitude of apparent depth. It is thus possible to make a distinction between scenes that contain more depth, and those that contain better depth.},
keywords = {3DPixx, RESPONSEPixx, VIEWPixx3D},
pubstate = {published},
tppubtype = {inproceedings}
}
Stereoscopic 3D viewing (S3D) can create a clear and compelling improvement in the quality of the 3D experience compared with 2D displays. This improvement is distinct from any change in the amount of depth perceived, or the apparent 3D shapes of objects and the distances between them. It has been suggested instead that the enhanced feeling of realness is associated more with the precision with which we see depth. We measured the contribution of stereoscopic cues to the quality of depth perception in simple abstract images and complex natural scenes. We varied the amount of disparity present in the simple scenes in order to dissociate the magnitude and precision of perceived depth. We show that the qualitative enhancement of perceived depth in stereoscopic displays can be readily quantified, and that it is more closely related to the precision than to the magnitude of apparent depth. It is thus possible to make a distinction between scenes that contain more depth, and those that contain better depth.
246.
Irwin, David E.; Robinson, Maria M.
Detection of Stimulus Displacements Across Saccades is Capacity-Limited and Biased in Favor of the Saccade Target Journal Article
In: Frontiers in Systems Neuroscience, vol. 9, pp. 161, 2015, ISSN: 1662-5137.
Abstract | Links | BibTeX | Tags: RESPONSEPixx
@article{irwin_detection_2015,
title = {Detection of Stimulus Displacements Across Saccades is Capacity-Limited and Biased in Favor of the Saccade Target},
author = {David E. Irwin and Maria M. Robinson},
url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4661269/},
doi = {10.3389/fnsys.2015.00161},
issn = {1662-5137},
year = {2015},
date = {2015-11-01},
urldate = {2024-01-02},
journal = {Frontiers in Systems Neuroscience},
volume = {9},
pages = {161},
abstract = {Retinal image displacements caused by saccadic eye movements are generally unnoticed. Recent theories have proposed that perceptual stability across saccades depends on a local evaluation process centered on the saccade target object rather than on remapping and evaluating the positions of all objects in a display. In three experiments, we examined whether objects other than the saccade target also influence perceptual stability by measuring displacement detection thresholds across saccades for saccade targets and a variable number of non-saccade objects. We found that the positions of multiple objects are maintained across saccades, but with variable precision, with the saccade target object having priority in the perception of displacement, most likely because it is the focus of attention before the saccade and resides near the fovea after the saccade. The perception of displacement of objects that are not the saccade target is affected by acuity limitations, attentional limitations, and limitations on memory capacity. Unlike previous studies that have found that a postsaccadic blank improves the detection of displacement direction across saccades, we found that postsaccadic blanking hurt the detection of displacement per se by increasing false alarms. Overall, our results are consistent with the hypothesis that visual working memory underlies the perception of stability across saccades.},
keywords = {RESPONSEPixx},
pubstate = {published},
tppubtype = {article}
}
Retinal image displacements caused by saccadic eye movements are generally unnoticed. Recent theories have proposed that perceptual stability across saccades depends on a local evaluation process centered on the saccade target object rather than on remapping and evaluating the positions of all objects in a display. In three experiments, we examined whether objects other than the saccade target also influence perceptual stability by measuring displacement detection thresholds across saccades for saccade targets and a variable number of non-saccade objects. We found that the positions of multiple objects are maintained across saccades, but with variable precision, with the saccade target object having priority in the perception of displacement, most likely because it is the focus of attention before the saccade and resides near the fovea after the saccade. The perception of displacement of objects that are not the saccade target is affected by acuity limitations, attentional limitations, and limitations on memory capacity. Unlike previous studies that have found that a postsaccadic blank improves the detection of displacement direction across saccades, we found that postsaccadic blanking hurt the detection of displacement per se by increasing false alarms. Overall, our results are consistent with the hypothesis that visual working memory underlies the perception of stability across saccades.
247.
Daar, Marwan; Wilson, Hugh R.
Masking with faces in central visual field under a variety of temporal schedules Journal Article
In: Vision Research, vol. 116, pp. 1–12, 2015, ISSN: 0042-6989.
Abstract | Links | BibTeX | Tags: VIEWPixx
@article{daar_masking_2015,
title = {Masking with faces in central visual field under a variety of temporal schedules},
author = {Marwan Daar and Hugh R. Wilson},
url = {https://www.sciencedirect.com/science/article/pii/S0042698915002850},
doi = {10.1016/j.visres.2015.09.002},
issn = {0042-6989},
year = {2015},
date = {2015-11-01},
urldate = {2024-01-12},
journal = {Vision Research},
volume = {116},
pages = {1–12},
abstract = {With a few exceptions, previous studies have explored masking using either a backward mask or a common onset trailing mask, but not both. In a series of experiments, we demonstrate the use of faces in central visual field as a viable method to study the relationship between these two types of mask schedule. We tested observers in a two alternative forced choice face identification task, where both target and mask comprised synthetic faces, and show that a simple model can successfully predict masking across a variety of masking schedules ranging from a backward mask to a common onset trailing mask and a number of intermediate variations. Our data are well accounted for by a window of sensitivity to mask interference that is centered at around 100ms.},
keywords = {VIEWPixx},
pubstate = {published},
tppubtype = {article}
}
With a few exceptions, previous studies have explored masking using either a backward mask or a common onset trailing mask, but not both. In a series of experiments, we demonstrate the use of faces in central visual field as a viable method to study the relationship between these two types of mask schedule. We tested observers in a two alternative forced choice face identification task, where both target and mask comprised synthetic faces, and show that a simple model can successfully predict masking across a variety of masking schedules ranging from a backward mask to a common onset trailing mask and a number of intermediate variations. Our data are well accounted for by a window of sensitivity to mask interference that is centered at around 100ms.
248.
Betz, Torsten; Shapley, Robert; Wichmann, Felix A.; Maertens, Marianne
Noise masking of White's illusion exposes the weakness of current spatial filtering models of lightness perception Journal Article
In: Journal of Vision, vol. 15, no. 14, pp. 1, 2015, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: DATAPixx, RESPONSEPixx
@article{betz_noise_2015,
title = {Noise masking of White's illusion exposes the weakness of current spatial filtering models of lightness perception},
author = {Torsten Betz and Robert Shapley and Felix A. Wichmann and Marianne Maertens},
url = {https://doi.org/10.1167/15.14.1},
doi = {10.1167/15.14.1},
issn = {1534-7362},
year = {2015},
date = {2015-10-01},
urldate = {2024-01-12},
journal = {Journal of Vision},
volume = {15},
number = {14},
pages = {1},
abstract = {Spatial filtering models are currently a widely accepted mechanistic account of human lightness perception. Their popularity can be ascribed to two reasons: They correctly predict how human observers perceive a variety of lightness illusions, and the processing steps involved in the models bear an apparent resemblance with known physiological mechanisms at early stages of visual processing. Here, we tested the adequacy of these models by probing their response to stimuli that have been modified by adding narrowband noise. Psychophysically, it has been shown that noise in the range of one to five cycles per degree (cpd) can drastically reduce the strength of some lightness phenomena, while noise outside this range has little or no effect on perceived lightness. Choosing White's illusion (White, 1979) as a test case, we replicated and extended the psychophysical results, and found that none of the spatial filtering models tested was able to reproduce the spatial frequency specific effect of narrowband noise. We discuss the reasons for failure for each model individually, but we argue that the failure is indicative of the general inadequacy of this class of spatial filtering models. Given the present evidence we do not believe that spatial filtering models capture the mechanisms that are responsible for producing many of the lightness phenomena observed in human perception. Instead we think that our findings support the idea that low-level contributions to perceived lightness are primarily determined by the luminance contrast at surface boundaries.},
keywords = {DATAPixx, RESPONSEPixx},
pubstate = {published},
tppubtype = {article}
}
Spatial filtering models are currently a widely accepted mechanistic account of human lightness perception. Their popularity can be ascribed to two reasons: They correctly predict how human observers perceive a variety of lightness illusions, and the processing steps involved in the models bear an apparent resemblance with known physiological mechanisms at early stages of visual processing. Here, we tested the adequacy of these models by probing their response to stimuli that have been modified by adding narrowband noise. Psychophysically, it has been shown that noise in the range of one to five cycles per degree (cpd) can drastically reduce the strength of some lightness phenomena, while noise outside this range has little or no effect on perceived lightness. Choosing White's illusion (White, 1979) as a test case, we replicated and extended the psychophysical results, and found that none of the spatial filtering models tested was able to reproduce the spatial frequency specific effect of narrowband noise. We discuss the reasons for failure for each model individually, but we argue that the failure is indicative of the general inadequacy of this class of spatial filtering models. Given the present evidence we do not believe that spatial filtering models capture the mechanisms that are responsible for producing many of the lightness phenomena observed in human perception. Instead we think that our findings support the idea that low-level contributions to perceived lightness are primarily determined by the luminance contrast at surface boundaries.
249.
Yazdani, Partow; Serrano-Pedraza, Ignacio; Whittaker, Roger G.; Trevelyan, Andrew; Read, Jenny C. A.
Two common psychophysical measures of surround suppression reflect independent neuronal mechanisms Journal Article
In: Journal of Vision, vol. 15, no. 13, pp. 21, 2015, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: DATAPixx, RESPONSEPixx
@article{yazdani_two_2015,
title = {Two common psychophysical measures of surround suppression reflect independent neuronal mechanisms},
author = {Partow Yazdani and Ignacio Serrano-Pedraza and Roger G. Whittaker and Andrew Trevelyan and Jenny C. A. Read},
url = {https://doi.org/10.1167/15.13.21},
doi = {10.1167/15.13.21},
issn = {1534-7362},
year = {2015},
date = {2015-09-01},
urldate = {2024-01-18},
journal = {Journal of Vision},
volume = {15},
number = {13},
pages = {21},
abstract = {Psychophysical surround suppression is believed to reflect inhibitory neuronal mechanisms in visual cortex. In recent years, two psychophysical measures of surround suppression have been much studied: (i) duration thresholds on a motion-discrimination task (which are worse for larger than for smaller stimuli) and (ii) contrast thresholds on a contrast-detection task (which are worse when grating stimuli are surrounded by a stimulus of the same orientation than when they are presented in isolation or surrounded by a stimulus of orthogonal orientation). Changes in both metrics have been linked to several different human conditions, including aging, differences in intelligence, and clinical disorders such as schizophrenia, depression, and autism. However, the exact nature of the neuronal correlate underlying these phenomena remains unclear. Here, we use an individual-differences approach to test the hypothesis that both measures reflect the same property of the visual system, e.g., the strength of GABA-ergic inhibition across visual cortex. Under this hypothesis we would expect the two measures to be significantly positively correlated across individuals. In fact, they are not significantly correlated. In addition, we replicate the previously reported correlation between age and motion-discrimination surround suppression, but find no correlation between age and contrast-detection surround suppression. We conclude that the two forms of psychophysical surround suppression arise independently from different cortical mechanisms.},
keywords = {DATAPixx, RESPONSEPixx},
pubstate = {published},
tppubtype = {article}
}
Psychophysical surround suppression is believed to reflect inhibitory neuronal mechanisms in visual cortex. In recent years, two psychophysical measures of surround suppression have been much studied: (i) duration thresholds on a motion-discrimination task (which are worse for larger than for smaller stimuli) and (ii) contrast thresholds on a contrast-detection task (which are worse when grating stimuli are surrounded by a stimulus of the same orientation than when they are presented in isolation or surrounded by a stimulus of orthogonal orientation). Changes in both metrics have been linked to several different human conditions, including aging, differences in intelligence, and clinical disorders such as schizophrenia, depression, and autism. However, the exact nature of the neuronal correlate underlying these phenomena remains unclear. Here, we use an individual-differences approach to test the hypothesis that both measures reflect the same property of the visual system, e.g., the strength of GABA-ergic inhibition across visual cortex. Under this hypothesis we would expect the two measures to be significantly positively correlated across individuals. In fact, they are not significantly correlated. In addition, we replicate the previously reported correlation between age and motion-discrimination surround suppression, but find no correlation between age and contrast-detection surround suppression. We conclude that the two forms of psychophysical surround suppression arise independently from different cortical mechanisms.
250.
Bays, Brett C.; Visscher, Kristina M.; Dantec, Christophe C. Le; Seitz, Aaron R.
Alpha-band EEG activity in perceptual learning Journal Article
In: Journal of Vision, vol. 15, no. 10, pp. 7, 2015, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: DATAPixx
@article{bays_alpha-band_2015,
title = {Alpha-band EEG activity in perceptual learning},
author = {Brett C. Bays and Kristina M. Visscher and Christophe C. Le Dantec and Aaron R. Seitz},
url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4570730/},
doi = {10.1167/15.10.7},
issn = {1534-7362},
year = {2015},
date = {2015-09-01},
urldate = {2023-12-21},
journal = {Journal of Vision},
volume = {15},
number = {10},
pages = {7},
abstract = {In studies of perceptual learning (PL), subjects are typically highly trained across many sessions to achieve perceptual benefits on the stimuli in those tasks. There is currently significant debate regarding what sources of brain plasticity underlie these PL-based learning improvements. Here we investigate the hypothesis that PL, among other mechanisms, leads to task automaticity, especially in the presence of the trained stimuli. To investigate this hypothesis, we trained participants for eight sessions to find an oriented target in a field of near-oriented distractors and examined alpha-band activity, which modulates with attention to visual stimuli, as a possible measure of automaticity. Alpha-band activity was acquired via electroencephalogram (EEG), before and after training, as participants performed the task with trained and untrained stimuli. Results show that participants underwent significant learning in this task (as assessed by threshold, accuracy, and reaction time improvements) and that alpha power increased during the pre-stimulus period and then underwent greater desynchronization at the time of stimulus presentation following training. However, these changes in alpha-band activity were not specific to the trained stimuli, with similar patterns of posttraining alpha power for trained and untrained stimuli. These data are consistent with the view that participants were more efficient at focusing resources at the time of stimulus presentation and are consistent with a greater automaticity of task performance. These findings have implications for PL, as transfer effects from trained to untrained stimuli may partially depend on differential effort of the individual at the time of stimulus processing.},
keywords = {DATAPixx},
pubstate = {published},
tppubtype = {article}
}
In studies of perceptual learning (PL), subjects are typically highly trained across many sessions to achieve perceptual benefits on the stimuli in those tasks. There is currently significant debate regarding what sources of brain plasticity underlie these PL-based learning improvements. Here we investigate the hypothesis that PL, among other mechanisms, leads to task automaticity, especially in the presence of the trained stimuli. To investigate this hypothesis, we trained participants for eight sessions to find an oriented target in a field of near-oriented distractors and examined alpha-band activity, which modulates with attention to visual stimuli, as a possible measure of automaticity. Alpha-band activity was acquired via electroencephalogram (EEG), before and after training, as participants performed the task with trained and untrained stimuli. Results show that participants underwent significant learning in this task (as assessed by threshold, accuracy, and reaction time improvements) and that alpha power increased during the pre-stimulus period and then underwent greater desynchronization at the time of stimulus presentation following training. However, these changes in alpha-band activity were not specific to the trained stimuli, with similar patterns of posttraining alpha power for trained and untrained stimuli. These data are consistent with the view that participants were more efficient at focusing resources at the time of stimulus presentation and are consistent with a greater automaticity of task performance. These findings have implications for PL, as transfer effects from trained to untrained stimuli may partially depend on differential effort of the individual at the time of stimulus processing.
251.
Betz, Torsten; Shapley, Robert; Wichmann, Felix A.; Maertens, Marianne
Testing the role of luminance edges in White's illusion with contour adaptation Journal Article
In: Journal of Vision, vol. 15, no. 11, pp. 14, 2015, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: DATAPixx, RESPONSEPixx
@article{betz_testing_2015,
title = {Testing the role of luminance edges in White's illusion with contour adaptation},
author = {Torsten Betz and Robert Shapley and Felix A. Wichmann and Marianne Maertens},
url = {https://doi.org/10.1167/15.11.14},
doi = {10.1167/15.11.14},
issn = {1534-7362},
year = {2015},
date = {2015-08-01},
urldate = {2024-01-18},
journal = {Journal of Vision},
volume = {15},
number = {11},
pages = {14},
abstract = {White's illusion is the perceptual effect that two equiluminant gray patches superimposed on a black-and-white square-wave grating appear different in lightness: A test patch placed on a dark stripe of the grating looks lighter than one placed on a light stripe. Although the effect does not depend on the aspect ratio of the test patches, and thus on the amount of border that is shared with either the dark or the light stripe, the context of each patch must, in a yet to be specified way, influence their lightness. We employed a contour adaptation paradigm (Anstis, 2013) to test the contribution of each of the test patches' edges to the perceived lightness of the test patches. We found that adapting to the edges that are oriented parallel to the grating slightly increased the lightness illusion, whereas adapting to the orthogonal edges abolished, or for some observers even reversed, the lightness illusion. We implemented a temporal adaptation mechanism in three spatial filtering models of lightness perception, and show that the models cannot account for the observed adaptation effects. We conclude that White's illusion is largely determined by edge contrast across the edge orthogonal to the grating, whereas the parallel edge has little or no influence. We suggest mechanisms that could explain this asymmetry.},
keywords = {DATAPixx, RESPONSEPixx},
pubstate = {published},
tppubtype = {article}
}
White's illusion is the perceptual effect that two equiluminant gray patches superimposed on a black-and-white square-wave grating appear different in lightness: A test patch placed on a dark stripe of the grating looks lighter than one placed on a light stripe. Although the effect does not depend on the aspect ratio of the test patches, and thus on the amount of border that is shared with either the dark or the light stripe, the context of each patch must, in a yet to be specified way, influence their lightness. We employed a contour adaptation paradigm (Anstis, 2013) to test the contribution of each of the test patches' edges to the perceived lightness of the test patches. We found that adapting to the edges that are oriented parallel to the grating slightly increased the lightness illusion, whereas adapting to the orthogonal edges abolished, or for some observers even reversed, the lightness illusion. We implemented a temporal adaptation mechanism in three spatial filtering models of lightness perception, and show that the models cannot account for the observed adaptation effects. We conclude that White's illusion is largely determined by edge contrast across the edge orthogonal to the grating, whereas the parallel edge has little or no influence. We suggest mechanisms that could explain this asymmetry.
252.
Goonetilleke, Samanthi C.; Katz, Leor; Wood, Daniel K.; Gu, Chao; Huk, Alexander C.; Corneil, Brian D.
In: Journal of Neurophysiology, vol. 114, no. 2, pp. 902–913, 2015, ISSN: 0022-3077.
Abstract | Links | BibTeX | Tags: DATAPixx
@article{goonetilleke_cross-species_2015,
title = {Cross-species comparison of anticipatory and stimulus-driven neck muscle activity well before saccadic gaze shifts in humans and nonhuman primates},
author = {Samanthi C. Goonetilleke and Leor Katz and Daniel K. Wood and Chao Gu and Alexander C. Huk and Brian D. Corneil},
url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4533108/},
doi = {10.1152/jn.00230.2015},
issn = {0022-3077},
year = {2015},
date = {2015-08-01},
urldate = {2024-01-02},
journal = {Journal of Neurophysiology},
volume = {114},
number = {2},
pages = {902–913},
abstract = {Recent studies have described a phenomenon wherein the onset of a peripheral visual stimulus elicits short-latency (<100 ms) stimulus-locked recruitment (SLR) of neck muscles in nonhuman primates (NHPs), well before any saccadic gaze shift. The SLR is thought to arise from visual responses within the intermediate layers of the superior colliculus (SCi), hence neck muscle recordings may reflect presaccadic activity within the SCi, even in humans. We obtained bilateral intramuscular recordings from splenius capitis (SPL, an ipsilateral head-turning muscle) from 28 human subjects performing leftward or rightward visually guided eye-head gaze shifts. Evidence of an SLR was obtained in 16/55 (29%) of samples; we also observed examples where the SLR was present only unilaterally. We compared these human results with those recorded from a sample of eight NHPs from which recordings of both SPL and deeper suboccipital muscles were available. Using the same criteria, evidence of an SLR was obtained in 8/14 (57%) of SPL recordings, but in 26/29 (90%) of recordings from suboccipital muscles. Thus, both species-specific and muscle-specific factors contribute to the low SLR prevalence in human SPL. Regardless of the presence of the SLR, neck muscle activity in both human SPL and in NHPs became predictive of the reaction time of the ensuing saccade gaze shift ∼70 ms after target appearance; such pregaze recruitment likely reflects developing SCi activity, even if the tectoreticulospinal pathway does not reliably relay visually related activity to SPL in humans.},
keywords = {DATAPixx},
pubstate = {published},
tppubtype = {article}
}
Recent studies have described a phenomenon wherein the onset of a peripheral visual stimulus elicits short-latency (<100 ms) stimulus-locked recruitment (SLR) of neck muscles in nonhuman primates (NHPs), well before any saccadic gaze shift. The SLR is thought to arise from visual responses within the intermediate layers of the superior colliculus (SCi), hence neck muscle recordings may reflect presaccadic activity within the SCi, even in humans. We obtained bilateral intramuscular recordings from splenius capitis (SPL, an ipsilateral head-turning muscle) from 28 human subjects performing leftward or rightward visually guided eye-head gaze shifts. Evidence of an SLR was obtained in 16/55 (29%) of samples; we also observed examples where the SLR was present only unilaterally. We compared these human results with those recorded from a sample of eight NHPs from which recordings of both SPL and deeper suboccipital muscles were available. Using the same criteria, evidence of an SLR was obtained in 8/14 (57%) of SPL recordings, but in 26/29 (90%) of recordings from suboccipital muscles. Thus, both species-specific and muscle-specific factors contribute to the low SLR prevalence in human SPL. Regardless of the presence of the SLR, neck muscle activity in both human SPL and in NHPs became predictive of the reaction time of the ensuing saccade gaze shift ∼70 ms after target appearance; such pregaze recruitment likely reflects developing SCi activity, even if the tectoreticulospinal pathway does not reliably relay visually related activity to SPL in humans.
253.
Yuasa, Kenichi; Yotsumoto, Yuko
Opposite Distortions in Interval Timing Perception for Visual and Auditory Stimuli with Temporal Modulations Journal Article
In: PLOS ONE, vol. 10, no. 8, pp. e0135646, 2015, ISSN: 1932-6203, (Publisher: Public Library of Science).
Abstract | Links | BibTeX | Tags: VIEWPixx3D
@article{yuasa_opposite_2015,
title = {Opposite Distortions in Interval Timing Perception for Visual and Auditory Stimuli with Temporal Modulations},
author = {Kenichi Yuasa and Yuko Yotsumoto},
url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0135646},
doi = {10.1371/journal.pone.0135646},
issn = {1932-6203},
year = {2015},
date = {2015-08-01},
urldate = {2024-01-16},
journal = {PLOS ONE},
volume = {10},
number = {8},
pages = {e0135646},
abstract = {When an object is presented visually and moves or flickers, the perception of its duration tends to be overestimated. Such an overestimation is called time dilation. Perceived time can also be distorted when a stimulus is presented aurally as an auditory flutter, but the mechanisms and their relationship to visual processing remains unclear. In the present study, we measured interval timing perception while modulating the temporal characteristics of visual and auditory stimuli, and investigated whether the interval times of visually and aurally presented objects shared a common mechanism. In these experiments, participants compared the durations of flickering or fluttering stimuli to standard stimuli, which were presented continuously. Perceived durations for auditory flutters were underestimated, while perceived durations of visual flickers were overestimated. When auditory flutters and visual flickers were presented simultaneously, these distortion effects were cancelled out. When auditory flutters were presented with a constantly presented visual stimulus, the interval timing perception of the visual stimulus was affected by the auditory flutters. These results indicate that interval timing perception is governed by independent mechanisms for visual and auditory processing, and that there are some interactions between the two processing systems.},
note = {Publisher: Public Library of Science},
keywords = {VIEWPixx3D},
pubstate = {published},
tppubtype = {article}
}
When an object is presented visually and moves or flickers, the perception of its duration tends to be overestimated. Such an overestimation is called time dilation. Perceived time can also be distorted when a stimulus is presented aurally as an auditory flutter, but the mechanisms and their relationship to visual processing remains unclear. In the present study, we measured interval timing perception while modulating the temporal characteristics of visual and auditory stimuli, and investigated whether the interval times of visually and aurally presented objects shared a common mechanism. In these experiments, participants compared the durations of flickering or fluttering stimuli to standard stimuli, which were presented continuously. Perceived durations for auditory flutters were underestimated, while perceived durations of visual flickers were overestimated. When auditory flutters and visual flickers were presented simultaneously, these distortion effects were cancelled out. When auditory flutters were presented with a constantly presented visual stimulus, the interval timing perception of the visual stimulus was affected by the auditory flutters. These results indicate that interval timing perception is governed by independent mechanisms for visual and auditory processing, and that there are some interactions between the two processing systems.
254.
Miyamoto, Kentaro; Murakami, Ikuya
Pupillary light reflex to light inside the natural blind spot Journal Article
In: Scientific Reports, vol. 5, no. 1, pp. 11862, 2015, ISSN: 2045-2322, (Number: 1 Publisher: Nature Publishing Group).
Abstract | Links | BibTeX | Tags: VIEWPixx
@article{miyamoto_pupillary_2015,
title = {Pupillary light reflex to light inside the natural blind spot},
author = {Kentaro Miyamoto and Ikuya Murakami},
url = {https://www.nature.com/articles/srep11862},
doi = {10.1038/srep11862},
issn = {2045-2322},
year = {2015},
date = {2015-06-01},
urldate = {2024-01-17},
journal = {Scientific Reports},
volume = {5},
number = {1},
pages = {11862},
abstract = {When a light stimulus covers the human natural blind spot (BS), perceptual filling-in corrects for the missing information inside the BS. Here, we examined whether a filled-in surface of light perceived inside the BS affects the size of the short-latency pupillary light reflex (PLR), a pupil response mediated by a subcortical pathway for unconscious vision. The PLR was not induced by a red surface that was physically absent but perceptually filled-in inside the BS in the presence of a red ring surrounding it. However, a white large disk covering the BS unexpectedly induced a larger PLR than a white ring surrounding the BS border did, even though these two stimuli must be equivalent for the visual system and trial-by-trial percepts did not predict PLR size. These results suggest that some physiological mechanism, presumably the retinal cells containing the photopigment melanopsin, receives the light projected inside the BS and enhances PLR.},
note = {Number: 1
Publisher: Nature Publishing Group},
keywords = {VIEWPixx},
pubstate = {published},
tppubtype = {article}
}
When a light stimulus covers the human natural blind spot (BS), perceptual filling-in corrects for the missing information inside the BS. Here, we examined whether a filled-in surface of light perceived inside the BS affects the size of the short-latency pupillary light reflex (PLR), a pupil response mediated by a subcortical pathway for unconscious vision. The PLR was not induced by a red surface that was physically absent but perceptually filled-in inside the BS in the presence of a red ring surrounding it. However, a white large disk covering the BS unexpectedly induced a larger PLR than a white ring surrounding the BS border did, even though these two stimuli must be equivalent for the visual system and trial-by-trial percepts did not predict PLR size. These results suggest that some physiological mechanism, presumably the retinal cells containing the photopigment melanopsin, receives the light projected inside the BS and enhances PLR.
255.
Wilson, Hugh R.; Propp, Roni
Detection and recognition of angular frequency patterns Journal Article
In: Vision Research, vol. 110, pp. 51–56, 2015, ISSN: 0042-6989.
Abstract | Links | BibTeX | Tags: VIEWPixx
@article{wilson_detection_2015,
title = {Detection and recognition of angular frequency patterns},
author = {Hugh R. Wilson and Roni Propp},
url = {https://www.sciencedirect.com/science/article/pii/S0042698915000760},
doi = {10.1016/j.visres.2015.02.022},
issn = {0042-6989},
year = {2015},
date = {2015-05-01},
urldate = {2024-01-02},
journal = {Vision Research},
volume = {110},
pages = {51–56},
abstract = {Previous research has extensively explored visual encoding of smoothly curved, closed contours described by sinusoidal variation of pattern radius as a function of polar angle (RF patterns). Although the contours of many biologically significant objects are curved, we also confront shapes with a more jagged and angular appearance. To study these, we introduce here a novel class of visual stimuli that deform smoothly from a circle to an equilateral polygon with N sides (AF patterns). Threshold measurements reveal that both AF and RF patterns can be discriminated from circles at the same deformation amplitude, approximately 18.0arcsec, which is in the hyperacuity range. Thresholds were slightly higher for patterns with 3.0 cycles than for those with 5.0 cycles. Discrimination between AF and RF patterns was 75% correct at an amplitude that was approximately 3.0 times the threshold amplitude, which implies that AF and RF patterns activate different neural populations. Experiments with jittered patterns in which the contour was broken into several pieces and shifted inward or outward had much less effect on AF patterns than on RF patterns. Similarly, thresholds for single angles of AF patterns showed no significant difference from thresholds for the entire AF pattern. Taken together, these results imply that the visual system incorporates angles explicitly in the representation of closed object contours, but it suggests that angular contours are represented more locally than are curved contours.},
keywords = {VIEWPixx},
pubstate = {published},
tppubtype = {article}
}
Previous research has extensively explored visual encoding of smoothly curved, closed contours described by sinusoidal variation of pattern radius as a function of polar angle (RF patterns). Although the contours of many biologically significant objects are curved, we also confront shapes with a more jagged and angular appearance. To study these, we introduce here a novel class of visual stimuli that deform smoothly from a circle to an equilateral polygon with N sides (AF patterns). Threshold measurements reveal that both AF and RF patterns can be discriminated from circles at the same deformation amplitude, approximately 18.0arcsec, which is in the hyperacuity range. Thresholds were slightly higher for patterns with 3.0 cycles than for those with 5.0 cycles. Discrimination between AF and RF patterns was 75% correct at an amplitude that was approximately 3.0 times the threshold amplitude, which implies that AF and RF patterns activate different neural populations. Experiments with jittered patterns in which the contour was broken into several pieces and shifted inward or outward had much less effect on AF patterns than on RF patterns. Similarly, thresholds for single angles of AF patterns showed no significant difference from thresholds for the entire AF pattern. Taken together, these results imply that the visual system incorporates angles explicitly in the representation of closed object contours, but it suggests that angular contours are represented more locally than are curved contours.
256.
Johnson, Paul V.; Kim, Joohwan; Banks, Martin S.
Stereoscopic 3D display technique using spatiotemporal interlacing has improved spatial and temporal properties Journal Article
In: Optics Express, vol. 23, no. 7, pp. 9252–9275, 2015, ISSN: 1094-4087, (Publisher: Optica Publishing Group).
Abstract | Links | BibTeX | Tags: DATAPixx
@article{johnson_stereoscopic_2015,
title = {Stereoscopic 3D display technique using spatiotemporal interlacing has improved spatial and temporal properties},
author = {Paul V. Johnson and Joohwan Kim and Martin S. Banks},
url = {https://opg.optica.org/oe/abstract.cfm?uri=oe-23-7-9252},
doi = {10.1364/OE.23.009252},
issn = {1094-4087},
year = {2015},
date = {2015-04-01},
urldate = {2024-01-17},
journal = {Optics Express},
volume = {23},
number = {7},
pages = {9252–9275},
abstract = {Stereoscopic 3D (S3D) displays use spatial or temporal interlacing to send different images to the two eyes. Temporal interlacing delivers images to the left and right eyes alternately in time; it has high effective spatial resolution but is prone to temporal artifacts. Spatial interlacing delivers even pixel rows to one eye and odd rows to the other eye simultaneously; it is subject to spatial limitations such as reduced spatial resolution. We propose a spatiotemporal-interlacing protocol that interlaces the left- and right-eye views spatially, but with the rows being delivered to each eye alternating with each frame. We performed psychophysical experiments and found that flicker, motion artifacts, and depth distortion are substantially reduced relative to the temporal-interlacing protocol, and spatial resolution is better than in the spatial-interlacing protocol. Thus, the spatiotemporal-interlacing protocol retains the benefits of spatial and temporal interlacing while minimizing or even eliminating the drawbacks.},
note = {Publisher: Optica Publishing Group},
keywords = {DATAPixx},
pubstate = {published},
tppubtype = {article}
}
Stereoscopic 3D (S3D) displays use spatial or temporal interlacing to send different images to the two eyes. Temporal interlacing delivers images to the left and right eyes alternately in time; it has high effective spatial resolution but is prone to temporal artifacts. Spatial interlacing delivers even pixel rows to one eye and odd rows to the other eye simultaneously; it is subject to spatial limitations such as reduced spatial resolution. We propose a spatiotemporal-interlacing protocol that interlaces the left- and right-eye views spatially, but with the rows being delivered to each eye alternating with each frame. We performed psychophysical experiments and found that flicker, motion artifacts, and depth distortion are substantially reduced relative to the temporal-interlacing protocol, and spatial resolution is better than in the spatial-interlacing protocol. Thus, the spatiotemporal-interlacing protocol retains the benefits of spatial and temporal interlacing while minimizing or even eliminating the drawbacks.
257.
Dormal, Giulia; Lepore, Franco; Harissi-Dagher, Mona; Albouy, Geneviève; Bertone, Armando; Rossion, Bruno; Collignon, Olivier
Tracking the evolution of crossmodal plasticity and visual functions before and after sight restoration Journal Article
In: Journal of Neurophysiology, vol. 113, no. 6, pp. 1727–1742, 2015, ISSN: 0022-3077, (Publisher: American Physiological Society).
Abstract | Links | BibTeX | Tags: DATAPixx, VPixxProgram
@article{dormal_tracking_2015,
title = {Tracking the evolution of crossmodal plasticity and visual functions before and after sight restoration},
author = {Giulia Dormal and Franco Lepore and Mona Harissi-Dagher and Geneviève Albouy and Armando Bertone and Bruno Rossion and Olivier Collignon},
url = {https://journals.physiology.org/doi/full/10.1152/jn.00420.2014},
doi = {10.1152/jn.00420.2014},
issn = {0022-3077},
year = {2015},
date = {2015-03-01},
urldate = {2024-01-18},
journal = {Journal of Neurophysiology},
volume = {113},
number = {6},
pages = {1727–1742},
abstract = {Visual deprivation leads to massive reorganization in both the structure and function of the occipital cortex, raising crucial challenges for sight restoration. We tracked the behavioral, structural, and neurofunctional changes occurring in an early and severely visually impaired patient before and 1.5 and 7 mo after sight restoration with magnetic resonance imaging. Robust presurgical auditory responses were found in occipital cortex despite residual preoperative vision. In primary visual cortex, crossmodal auditory responses overlapped with visual responses and remained elevated even 7 mo after surgery. However, these crossmodal responses decreased in extrastriate occipital regions after surgery, together with improved behavioral vision and with increases in both gray matter density and neural activation in low-level visual regions. Selective responses in high-level visual regions involved in motion and face processing were observable even before surgery and did not evolve after surgery. Taken together, these findings demonstrate that structural and functional reorganization of occipital regions are present in an individual with a long-standing history of severe visual impairment and that such reorganizations can be partially reversed by visual restoration in adulthood.},
note = {Publisher: American Physiological Society},
keywords = {DATAPixx, VPixxProgram},
pubstate = {published},
tppubtype = {article}
}
Visual deprivation leads to massive reorganization in both the structure and function of the occipital cortex, raising crucial challenges for sight restoration. We tracked the behavioral, structural, and neurofunctional changes occurring in an early and severely visually impaired patient before and 1.5 and 7 mo after sight restoration with magnetic resonance imaging. Robust presurgical auditory responses were found in occipital cortex despite residual preoperative vision. In primary visual cortex, crossmodal auditory responses overlapped with visual responses and remained elevated even 7 mo after surgery. However, these crossmodal responses decreased in extrastriate occipital regions after surgery, together with improved behavioral vision and with increases in both gray matter density and neural activation in low-level visual regions. Selective responses in high-level visual regions involved in motion and face processing were observable even before surgery and did not evolve after surgery. Taken together, these findings demonstrate that structural and functional reorganization of occipital regions are present in an individual with a long-standing history of severe visual impairment and that such reorganizations can be partially reversed by visual restoration in adulthood.
258.
Watson, Andrew B.; Ahumada, Albert J.
Letter identification and the Neural Image Classifier Journal Article
In: Journal of Vision, vol. 15, no. 2, pp. 15, 2015, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: VIEWPixx
@article{watson_letter_2015,
title = {Letter identification and the Neural Image Classifier},
author = {Andrew B. Watson and Albert J. Ahumada},
url = {https://doi.org/10.1167/15.2.15},
doi = {10.1167/15.2.15},
issn = {1534-7362},
year = {2015},
date = {2015-02-01},
urldate = {2024-01-12},
journal = {Journal of Vision},
volume = {15},
number = {2},
pages = {15},
abstract = {Letter identification is an important visual task for both practical and theoretical reasons. To extend and test existing models, we have reviewed published data for contrast sensitivity for letter identification as a function of size and have also collected new data. Contrast sensitivity increases rapidly from the acuity limit but slows and asymptotes at a symbol size of about 1 degree. We recast these data in terms of contrast difference energy: the average of the squared distances between the letter images and the average letter image. In terms of sensitivity to contrast difference energy, and thus visual efficiency, there is a peak around ¼ degree, followed by a marked decline at larger sizes. These results are explained by a Neural Image Classifier model that includes optical filtering and retinal neural filtering, sampling, and noise, followed by an optimal classifier. As letters are enlarged, sensitivity declines because of the increasing size and spacing of the midget retinal ganglion cell receptive fields in the periphery.},
keywords = {VIEWPixx},
pubstate = {published},
tppubtype = {article}
}
Letter identification is an important visual task for both practical and theoretical reasons. To extend and test existing models, we have reviewed published data for contrast sensitivity for letter identification as a function of size and have also collected new data. Contrast sensitivity increases rapidly from the acuity limit but slows and asymptotes at a symbol size of about 1 degree. We recast these data in terms of contrast difference energy: the average of the squared distances between the letter images and the average letter image. In terms of sensitivity to contrast difference energy, and thus visual efficiency, there is a peak around ¼ degree, followed by a marked decline at larger sizes. These results are explained by a Neural Image Classifier model that includes optical filtering and retinal neural filtering, sampling, and noise, followed by an optimal classifier. As letters are enlarged, sensitivity declines because of the increasing size and spacing of the midget retinal ganglion cell receptive fields in the periphery.
259.
Ghodrati, Masoud; Morris, Adam P.; Price, Nicholas Seow Chiang
The (un)suitability of modern liquid crystal displays (LCDs) for vision research Journal Article
In: Frontiers in Psychology, vol. 6, 2015, ISSN: 1664-1078.
Abstract | Links | BibTeX | Tags: VIEWPixx3D
@article{ghodrati_suitability_2015,
title = {The (un)suitability of modern liquid crystal displays (LCDs) for vision research},
author = {Masoud Ghodrati and Adam P. Morris and Nicholas Seow Chiang Price},
url = {https://www.frontiersin.org/articles/10.3389/fpsyg.2015.00303},
issn = {1664-1078},
year = {2015},
date = {2015-01-01},
urldate = {2023-12-21},
journal = {Frontiers in Psychology},
volume = {6},
abstract = {Psychophysical and physiological studies of vision have traditionally used cathode ray tube (CRT) monitors to present stimuli. These monitors are no longer easily available, and liquid crystal display (LCD) technology is continually improving; therefore, we characterized a number of LCD monitors to determine if newer models are suitable replacements for CRTs in the laboratory. We compared the spatial and temporal characteristics of a CRT with five LCDs, including monitors designed with vision science in mind (ViewPixx and Display++), “prosumer” gaming monitors, and a consumer-grade LCD. All monitors had sufficient contrast, luminance range and reliability to support basic vision experiments with static images. However, the luminance of all LCDs depended strongly on viewing angle, which in combination with the poor spatial uniformity of all monitors except the VPixx, caused up to 80% drops in effective luminance in the periphery during central fixation. Further, all monitors showed significant spatial dependence, as the luminance of one area was modulated by the luminance of other areas. These spatial imperfections are most pronounced for experiments that use large or peripheral visual stimuli. In the temporal domain, the gaming LCDs were unable to generate reliable luminance patterns; one was unable to reach the requested luminance within a single frame whereas in the other the luminance of one frame affected the luminance of the next frame. The VPixx and Display++ were less affected by these problems, and had good temporal properties provided stimuli were presented for 2 or more frames. Of the consumer-grade and gaming displays tested, and if problems with spatial uniformity are taken into account, the Eizo FG2421 is the most suitable alternative to CRTs. The specialized ViewPixx performed best among all the tested LCDs, followed closely by the Display++; both are good replacements for a CRT, provided their spatial imperfections are considered.},
keywords = {VIEWPixx3D},
pubstate = {published},
tppubtype = {article}
}
Psychophysical and physiological studies of vision have traditionally used cathode ray tube (CRT) monitors to present stimuli. These monitors are no longer easily available, and liquid crystal display (LCD) technology is continually improving; therefore, we characterized a number of LCD monitors to determine if newer models are suitable replacements for CRTs in the laboratory. We compared the spatial and temporal characteristics of a CRT with five LCDs, including monitors designed with vision science in mind (ViewPixx and Display++), “prosumer” gaming monitors, and a consumer-grade LCD. All monitors had sufficient contrast, luminance range and reliability to support basic vision experiments with static images. However, the luminance of all LCDs depended strongly on viewing angle, which in combination with the poor spatial uniformity of all monitors except the VPixx, caused up to 80% drops in effective luminance in the periphery during central fixation. Further, all monitors showed significant spatial dependence, as the luminance of one area was modulated by the luminance of other areas. These spatial imperfections are most pronounced for experiments that use large or peripheral visual stimuli. In the temporal domain, the gaming LCDs were unable to generate reliable luminance patterns; one was unable to reach the requested luminance within a single frame whereas in the other the luminance of one frame affected the luminance of the next frame. The VPixx and Display++ were less affected by these problems, and had good temporal properties provided stimuli were presented for 2 or more frames. Of the consumer-grade and gaming displays tested, and if problems with spatial uniformity are taken into account, the Eizo FG2421 is the most suitable alternative to CRTs. The specialized ViewPixx performed best among all the tested LCDs, followed closely by the Display++; both are good replacements for a CRT, provided their spatial imperfections are considered.
260.
Read, Jenny C. A.; Georgiou, Renos; Brash, Claire; Yazdani, Partow; Whittaker, Roger; Trevelyan, Andrew J.; Serrano-Pedraza, Ignacio
Moderate acute alcohol intoxication has minimal effect on surround suppression measured with a motion direction discrimination task Journal Article
In: Journal of Vision, vol. 15, no. 1, pp. 5, 2015, ISSN: 1534-7362.
Abstract | Links | BibTeX | Tags: DATAPixx, RESPONSEPixx
@article{read_moderate_2015,
title = {Moderate acute alcohol intoxication has minimal effect on surround suppression measured with a motion direction discrimination task},
author = {Jenny C. A. Read and Renos Georgiou and Claire Brash and Partow Yazdani and Roger Whittaker and Andrew J. Trevelyan and Ignacio Serrano-Pedraza},
url = {https://doi.org/10.1167/15.1.5},
doi = {10.1167/15.1.5},
issn = {1534-7362},
year = {2015},
date = {2015-01-01},
urldate = {2024-01-03},
journal = {Journal of Vision},
volume = {15},
number = {1},
pages = {5},
abstract = {A well-studied paradox of motion perception is that, in order to correctly judge direction in high-contrast stimuli, subjects need to observe motion for longer in large stimuli than in small stimuli. This effect is one of several perceptual effects known generally as “surround suppression.” It is usually attributed to center-surround antagonism between neurons in visual cortex, believed to be mediated by GABA-ergic inhibition. Accordingly, several studies have reported that this index of surround suppression is reduced in groups known to have reduced GABA-ergic inhibition, including older people and people with schizophrenia and major depressive disorder. In this study, we examined the effect on this index of moderate amounts of ethanol alcohol. Among its many effects on the nervous system, alcohol potentiates GABA-ergic transmission. We therefore hypothesized that it should further impair the perception of motion in large stimuli, resulting in a stronger surround-suppression index. This prediction was not borne out. Alcohol consumption slightly worsened duration thresholds for both large and small stimuli, but their ratio did not change significantly.},
keywords = {DATAPixx, RESPONSEPixx},
pubstate = {published},
tppubtype = {article}
}
A well-studied paradox of motion perception is that, in order to correctly judge direction in high-contrast stimuli, subjects need to observe motion for longer in large stimuli than in small stimuli. This effect is one of several perceptual effects known generally as “surround suppression.” It is usually attributed to center-surround antagonism between neurons in visual cortex, believed to be mediated by GABA-ergic inhibition. Accordingly, several studies have reported that this index of surround suppression is reduced in groups known to have reduced GABA-ergic inhibition, including older people and people with schizophrenia and major depressive disorder. In this study, we examined the effect on this index of moderate amounts of ethanol alcohol. Among its many effects on the nervous system, alcohol potentiates GABA-ergic transmission. We therefore hypothesized that it should further impair the perception of motion in large stimuli, resulting in a stronger surround-suppression index. This prediction was not borne out. Alcohol consumption slightly worsened duration thresholds for both large and small stimuli, but their ratio did not change significantly.