scholarly journals No Evidence for a Single Oscillator Underlying Discrete Visual Percepts

2021 ◽  
Author(s):  
Audrey Morrow ◽  
Jason Samaha
Keyword(s):  
Spatial Location ◽  
Alpha Band ◽  
Band Frequency ◽  
Discrete Sampling ◽  
Stationary Stimulus ◽  
Zero Correlation ◽  
Stimulus Detection ◽  
Single Oscillator ◽  
Moving Stimulus ◽  
Visual Consciousness

AbstractTheories of perception based on discrete sampling posit that visual consciousness is reconstructed based on snapshot-like perceptual moments, as opposed to being updated continuously. According to a model proposed by Schneider (2018), discrete sampling can explain both the flash-lag and the Fröhlich illusion, whereby a lag in the conscious updating of a moving stimulus alters its perceived spatial location in comparison to a stationary stimulus. The alpha-band frequency, which is associated with phasic modulation of stimulus detection and the temporal resolution of perception, has been proposed to reflect the duration of perceptual moments. The goal of this study was to determine whether a single oscillator (e.g., alpha) is underlying the duration of perceptual moments, which would predict that the point of subjective equality (PSE) in the flash-lag and Fröhlich illusions are positively correlated across individuals. Although our displays induced robust flash-lag and Fröhlich effects, virtually zero correlation was seen between the PSE in the two illusions, indicating that the illusion magnitudes are unrelated across observers. These findings suggest that, if discrete sampling theory is true, these illusory percepts either rely on different oscillatory frequencies or not on oscillations at all. Alternatively, discrete sampling may not be the mechanism underlying these two motion illusions or our methods were ill-suited to test the theory.

Alpha band frequency differences between low-trait and high-trait anxious individuals

Neuroreport ◽  
2018 ◽  
Vol 29 (2) ◽  
pp. 79-83 ◽  
Author(s):  
Richard T. Ward ◽  
Shelby L. Smith ◽  
Brian T. Kraus ◽  
Anna V. Allen ◽  
Michael A. Moses ◽  
...  
Keyword(s):  
Alpha Band ◽  
Band Frequency ◽  
High Trait

Somatosensory Anticipatory Alpha Activity Increases to Suppress Distracting Input

2012 ◽  
Vol 24 (3) ◽  
pp. 677-685 ◽  
Author(s):  
Saskia Haegens ◽  
Lisa Luther ◽  
Ole Jensen
Keyword(s):  
Task Performance ◽  
Discrimination Task ◽  
Discrimination Performance ◽  
Alpha Activity ◽  
Task Demands ◽  
Alpha Power ◽  
Alpha Band ◽  
Stimulus Detection ◽  
Engagement And Disengagement ◽  
Band Activity

Effective processing of sensory input in daily life requires attentional selection and amplification of relevant input and, just as importantly, attenuation of irrelevant information. It has been proposed that top–down modulation of oscillatory alpha band activity (8–14 Hz) serves to allocate resources to various regions, depending on task demands. In previous work, we showed that contralateral somatosensory alpha activity decreases to facilitate processing of an anticipated target stimulus in a tactile discrimination task. In the current study, we asked whether somatosensory alpha activity is also modulated when expecting incoming distracting stimuli on the nonattended side. We hypothesized that an ipsilateral increase of alpha to suppress distracters would be required for optimal task performance. We recorded magneto-encephalography while subjects performed a tactile stimulus discrimination task where a cue directed attention either to their left or right hand. Distracters were presented simultaneously to the unattended hand. We found that alpha power contralateral to the attended hand decreased, whereas ipsilateral alpha power increased. In addition, posterior alpha power showed a general increase. Importantly, these three alpha components all contributed to discrimination performance. This study further extends the notion that alpha band activity is involved in shaping the functional architecture of the working brain by determining the engagement and disengagement of specific regions: Contralateral alpha decreases to facilitate stimulus detection, whereas ipsilateral alpha increases when active suppression of distracters is required. Importantly, the ipsilateral alpha increase is crucial for optimal task performance.

scholarly journals Decoding and Reconstructing the Focus of Spatial Attention from the Topography of Alpha-band Oscillations

2016 ◽  
Vol 28 (8) ◽  
pp. 1090-1097 ◽  
Author(s):  
Jason Samaha ◽  
Thomas C. Sprague ◽  
Bradley R. Postle
Keyword(s):  
Spatial Attention ◽  
Sustained Attention ◽  
Spatial Location ◽  
Covert Attention ◽  
Alpha Power ◽  
Alpha Band ◽  
Temporal Precision ◽  
Neural Populations ◽  
Stimulus Features ◽  
Spatial Locations

Many aspects of perception and cognition are supported by activity in neural populations that are tuned to different stimulus features (e.g., orientation, spatial location, color). Goal-directed behavior, such as sustained attention, requires a mechanism for the selective prioritization of contextually appropriate representations. A candidate mechanism of sustained spatial attention is neural activity in the alpha band (8–13 Hz), whose power in the human EEG covaries with the focus of covert attention. Here, we applied an inverted encoding model to assess whether spatially selective neural responses could be recovered from the topography of alpha-band oscillations during spatial attention. Participants were cued to covertly attend to one of six spatial locations arranged concentrically around fixation while EEG was recorded. A linear classifier applied to EEG data during sustained attention demonstrated successful classification of the attended location from the topography of alpha power, although not from other frequency bands. We next sought to reconstruct the focus of spatial attention over time by applying inverted encoding models to the topography of alpha power and phase. Alpha power, but not phase, allowed for robust reconstructions of the specific attended location beginning around 450 msec postcue, an onset earlier than previous reports. These results demonstrate that posterior alpha-band oscillations can be used to track activity in feature-selective neural populations with high temporal precision during the deployment of covert spatial attention.

Foveal Flicker Fusion Using a Moving Stimulus

1965 ◽  
Vol 21 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Grant D. Miller ◽  
Duane A. Anderson ◽  
Ernst Simonson
Keyword(s):  
Linear Increase ◽  
Multiple Correlation ◽  
Experimental Conditions ◽  
Flicker Fusion Frequency ◽  
Stimulus Velocity ◽  
Stationary Stimulus ◽  
Moving Stimulus ◽  
The Relationship ◽  
Flicker Fusion ◽  
Sweep Speed

The relationship between stimulus velocity and the critical-flicker-fusion frequency (CFF) of an intermittent visual stimulus was investigated by modulating the sweep-speed and intensity of an oscilloscope beam. When Ss fixated upon a stationary point, CFF showed an approximately linear increase as a function of velocity. Velocity did not, however, influence CFF when S fixated on the moving stimulus. The multiple correlation (.68) between CFF determinations obtained with a stationary stimulus vs those obtained with several different velocities implies that the same mechanisms which determined CFF under the former condition were also operative in the latter. The trend of the bivariate correlations between the average CFF values for isolated pairs of experimental conditions suggests that an additional factor, possibly spatial acuity, may have become progressively dominant as velocities exceeded 1.08°/sec.

Asymmetric Mislocalization of a Visual Flash Ahead of and behind a Moving Object

Perception ◽  
10.1068/p5415 ◽  
2005 ◽  
Vol 34 (6) ◽  
pp. 687-698 ◽  
Author(s):  
Katsumi Watanabe
Keyword(s):  
Smooth Pursuit ◽  
Dual Task ◽  
Underlying Mechanism ◽  
Moving Object ◽  
Spatial Bias ◽  
Visual Objects ◽  
Spatial Asymmetry ◽  
Stationary Stimulus ◽  
Moving Stimulus

When subjects localize a flash relative to another stationary stimulus, the flash appears displaced in the direction of nearby motion signals (position capture; Whitney and Cavanagh, 2000 Nature Neuroscience3 954–959). Our previous study had suggested that the position capture is larger for a flash presented ahead of a moving stimulus than for a flash behind it (Watanabe et al, 2003 Perception32 545–559). In the present study, I investigated the spatial asymmetry of position capture. Experiment 1 demonstrated that asymmetric position capture occurs primarily in a moving-object-centered coordinate. Experiment 2 showed evidence that the asymmetric position capture operates after individuation of single visual objects. Finally, experiment 3 demonstrated that, when attention was reduced with a dual-task procedure, the asymmetric position capture increased. These results suggest that the spatial asymmetry of position capture occurs without attention but the spatial bias can be reduced by attention. Therefore, the underlying mechanism for the asymmetric spatial bias may be different from attentive tracking (Cavanagh, 1992 Science257 1563–1565) and mislocalization during smooth pursuit (Brenner et al, 2001 Vision Research41 2253–2259).

scholarly journals Perceptual compression of space through position integration

2006 ◽  
Vol 273 (1600) ◽  
pp. 2507-2512 ◽  
Author(s):  
Barrie W Roulston ◽  
Matt W Self ◽  
Semir Zeki
Keyword(s):  
Visual Space ◽  
Moving Object ◽  
Final Position ◽  
Short Time Period ◽  
Stationary Stimulus ◽  
Time Period ◽  
Lag Effect ◽  
Moving Stimulus ◽  
Short Time ◽  
Direction Opposite

The mechanism of positional localization has recently been debated due to interest in the flash-lag effect, which occurs when a briefly flashed stationary stimulus is perceived to lag behind a spatially aligned moving stimulus. Here we report positional localization observed at motion offsets as well as at onsets. In the ‘flash-lead’ effect, a moving object is perceived to be behind a spatially concurrent stationary flash before the two disappear. With ‘reverse-repmo’, subjects mis-localize the final position of a moving bar in the direction opposite to the trajectory of motion. Finally, we demonstrate that simultaneous onset and offset effects lead to a perceived compression of visual space. By characterizing illusory effects observed at motion offsets as well as at onsets, we provide evidence that the perceived position of a moving object is the result of an averaging process over a short time period, weighted towards the most recent positions. Our account explains a variety of motion illusions, including the compression of moving shapes when viewed through apertures.

scholarly journals The role of alpha-band frequency activity during performance of a visual-motoric interhemispheric transfer task.

2018 ◽  
Vol 18 (10) ◽  
pp. 437
Author(s):  
Stephanie Simon-Dack ◽  
Brian Kraus ◽  
Zachary Walter ◽  
Chelsea Cadle ◽  
Shelby Smith
Keyword(s):  
Transfer Task ◽  
Interhemispheric Transfer ◽  
Alpha Band ◽  
Band Frequency

Visual Motion Induces Effector Movement

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 280-280 ◽  
Author(s):  
D Nattkemper
Keyword(s):  
Visual Motion ◽  
Spatial Location ◽  
Perceptual Content ◽  
Left Hand ◽  
Stimulus Response ◽  
Spatial Stimulus ◽  
Spatial Properties ◽  
Moving Stimulus ◽  
The Right ◽  
Hand Response

A left-hand response to a left-hand stimulus is faster than a right-hand response to the same stimulus, even when spatial location is irrelevant to the task at hand. The existence of this spatial stimulus-response correspondence effect suggests that spatial properties of actions to be performed can be pre-specified by spatial properties of perceived events, so that actions are induced by perceptual content. If this view is correct, one should be able to show that not only spatial positions of actions can be pre-specified by properties of perceived events, but other features of actions as well. Specifically, I attempt to show that the direction of a to-be-executed movement can be specified by the direction of a moving stimulus. To study this question a variant of the Simon paradigm was developed: subjects were required to monitor a spot-like stimulus moving from left to right or from right to left on a display. At some point in time the spot would change its colour (from white to blue or red) and the subject had to respond differentially to the respective colour. Two aspects of this situation were varied. First, the type of the action-relevant signal was varied: it could either be a dynamic moving signal or a static non-moving one. Second, the type of response was varied: subjects were required to respond to the colour either with a dynamic response (moving a stylus to the left or right) or with a more static response (pressing a button on the left or on the right).

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