Invisible Adaptation: The Effect of Awareness on the Strength of the Motion Aftereffect

Perception ◽  
2020 ◽  
Vol 49 (8) ◽  
pp. 835-857
Author(s):  
Daphne Roumani ◽  
Konstantinos Moutoussis
Keyword(s):  
Visual Processing ◽  
Discrimination Task ◽  
Motion Aftereffect ◽  
Stimulus Strength ◽  
Perceptual Awareness ◽  
Physical Stimulus ◽  
Adaptation Stimulus ◽  
Unconscious Processing ◽  
Total Absence ◽  
Direction Discrimination

The ability to process information despite the lack of perceptual awareness is one of the most fascinating aspects of the visual system. Such unconscious processing is often investigated using adaptation, where any presence of the former can be traced by its footprint on aftereffects following the latter. We have investigated the mechanisms of the motion aftereffect (MAE) using random dot displays of varying motion coherence as well as crowding to modulate both the physical as well as the perceptual strength of the adaptation stimulus. Perceptual strength was quantitatively measured as the performance in a forced-choice direction-discrimination task. A motion-nulling technique was used to quantitatively measure the strength of the MAE. We show that the strength of the dynamic MAE is independently influenced by both the physical stimulus strength as well as the subjective perceptual strength, with the effect of the former being more prominent than that of the latter. We further show that the MAE still persists under conditions of subthreshold perception. Our results suggest that perceptual awareness can influence the strength of visual processing, but the latter is not fully dependent on the former and can still take place at its partial or even total absence.

scholarly journals Electrophysiological aftereffects of high-frequency transcranial random noise stimulation (hf-tRNS): an EEG investigation

2021 ◽  
Author(s):  
Filippo Ghin ◽  
Louise O’Hare ◽  
Andrea Pavan
Keyword(s):  
High Frequency ◽  
Discrimination Task ◽  
Temporal Dynamics ◽  
Random Noise ◽  
Decomposition Analysis ◽  
Oscillatory Activity ◽  
Motion Direction ◽  
Time Frequency ◽  
Direction Discrimination ◽  
Transcranial Random Noise Stimulation

AbstractThere is evidence that high-frequency transcranial random noise stimulation (hf-tRNS) is effective in improving behavioural performance in several visual tasks. However, so far there has been limited research into the spatial and temporal characteristics of hf-tRNS-induced facilitatory effects. In the present study, electroencephalogram (EEG) was used to investigate the spatial and temporal dynamics of cortical activity modulated by offline hf-tRNS on performance on a motion direction discrimination task. We used EEG to measure the amplitude of motion-related VEPs over the parieto-occipital cortex, as well as oscillatory power spectral density (PSD) at rest. A time–frequency decomposition analysis was also performed to investigate the shift in event-related spectral perturbation (ERSP) in response to the motion stimuli between the pre- and post-stimulation period. The results showed that the accuracy of the motion direction discrimination task was not modulated by offline hf-tRNS. Although the motion task was able to elicit motion-dependent VEP components (P1, N2, and P2), none of them showed any significant change between pre- and post-stimulation. We also found a time-dependent increase of the PSD in alpha and beta bands regardless of the stimulation protocol. Finally, time–frequency analysis showed a modulation of ERSP power in the hf-tRNS condition for gamma activity when compared to pre-stimulation periods and Sham stimulation. Overall, these results show that offline hf-tRNS may induce moderate aftereffects in brain oscillatory activity.

Target Selection for Saccadic Eye Movements: Direction-Selective Visual Responses in the Superior Colliculus

2001 ◽  
Vol 86 (5) ◽  
pp. 2527-2542 ◽  
Author(s):  
Gregory D. Horwitz ◽  
William T. Newsome
Keyword(s):  
Superior Colliculus ◽  
Eye Movement ◽  
Discrimination Task ◽  
Visual Motion ◽  
Target Selection ◽  
Small Population ◽  
Saccade Target ◽  
Visual Responses ◽  
Direction Discrimination ◽  
Deep Layers

We investigated the role of the superior colliculus (SC) in saccade target selection in rhesus monkeys who were trained to perform a direction-discrimination task. In this task, the monkey discriminated between opposed directions of visual motion and indicated its judgment by making a saccadic eye movement to one of two visual targets that were spatially aligned with the two possible directions of motion in the display. Thus the neural circuits that implement target selection in this task are likely to receive directionally selective visual inputs and be closely linked to the saccadic system. We therefore studied prelude neurons in the intermediate and deep layers of the SC that can discharge up to several seconds before an impending saccade, indicating a relatively high-level role in saccade planning. We used the direction-discrimination task to identify neurons whose prelude activity “predicted” the impending perceptual report several seconds before the animal actually executed the operant eye movement; these “choice predicting” cells comprised ∼30% of the neurons we encountered in the intermediate and deep layers of the SC. Surprisingly, about half of these prelude cells yielded direction-selective responses to our motion stimulus during a passive fixation task. In general, these neurons responded to motion stimuli in many locations around the visual field including the center of gaze where the visual discriminanda were positioned during the direction-discrimination task. Preferred directions generally pointed toward the location of the movement field of the SC neuron in accordance with the sensorimotor demands of the discrimination task. Control experiments indicate that the directional responses do not simply reflect covertly planned saccades. Our results indicate that a small population of SC prelude neurons exhibits properties appropriate for linking stimulus cues to saccade target selection in the context of a visual discrimination task.

scholarly journals Contribution of configural information in a direction discrimination task: Evidence using a novel masking paradigm

2009 ◽  
Vol 49 (20) ◽  
pp. 2503-2508 ◽  
Author(s):  
Lawrie S. McKay ◽  
David R. Simmons ◽  
Phil McAleer ◽  
Frank E. Pollick
Keyword(s):  
Discrimination Task ◽  
Configural Information ◽  
Direction Discrimination

The Duration of the Motion Aftereffect following Adaptation to First-Order and Second-Order Motion

Perception ◽  
1994 ◽  
Vol 23 (10) ◽  
pp. 1211-1219 ◽  
Author(s):  
Timothy Ledgeway ◽  
Andrew T Smith
Keyword(s):  
Motion Aftereffect ◽  
Second Order ◽  
Adaptation Stimulus ◽  
Motion Patterns ◽  
First Order ◽  
Parallel Motion ◽  
Significant Difference ◽  
Cross Adaptation ◽  
Identification Threshold ◽  
Direction Opposite

The magnitude of the motion aftereffect (MAE) obtained following adaptation to first-order or to second-order motion was measured by estimating its duration. The second-order adaptation stimulus was composed of contrast-modulated noise produced by multiplying two-dimensional (2-D) noise by a drifting 1 cycle deg−1 sine grating. The first-order adaptation stimulus was composed of luminance-modulated noise produced by summing, rather than multiplying, the noise and the sine grating. The test stimuli were directionally ambiguous motion patterns composed of either two oppositely drifting sine gratings added to noise or the contrast-modulated equivalent. The adaptation and test stimuli were equated for visibility by presenting them at the same multiple of direction-identification threshold. All possible combinations of first-order and second-order adaptation and test stimuli were examined in order to compare the magnitudes of the MAEs obtained following same adaptation and cross adaptation. After adaptation the test stimuli always appeared to drift coherently in the direction opposite to that of adaptation and the magnitudes of this MAE were very similar for all conditions examined. Statistical analyses of the results showed that there was no significant difference between the durations of the MAEs obtained in the same-adaptation and cross-adaptation conditions. The cross-adaptation effects suggest that either first-order or second-order motion are detected by a common low-level mechanism, or that separate parallel motion-detecting mechanisms exist, for the two types of motion, that interact at some later stage of processing.

A Selective History of the Study of Visual Motion Aftereffects

Perception ◽  
1994 ◽  
Vol 23 (10) ◽  
pp. 1111-1134 ◽  
Author(s):  
Nicholas J Wade
Keyword(s):  
Visual Processing ◽  
Visual Motion ◽  
Motion Aftereffect ◽  
Theoretical Research ◽  
Motion Processing ◽  
Visual Science ◽  
Stationary Objects ◽  
Major Review ◽  
Cortical Visual Processing ◽  
Motion Aftereffects

The visual motion aftereffect (MAE) was initially described after observation of movements in the natural environment, like those seen in rivers and waterfalls: stationary objects appeared to move briefly in the opposite direction. In the second half of the nineteenth century the MAE was displaced into the laboratory for experimental enquiry with the aid of Plateau's spiral. Such was the interest in the phenomenon that a major review of empirical and theoretical research was written in 1911. In the latter half of the present century novel stimuli (like drifting gratings, isoluminance patterns, spatial and luminance ramps, random-dot kinematograms, and first-order and second-order motions), introduced to study space and motion perception generally, have been applied to examine MAEs. Developing theories of cortical visual processing have drawn upon MAEs to provide a link between psychophysics and physiology; this has been most pronounced in the context of monocular and binocular channels in the visual system, the combination of colour and contour information, and in the cortical sites most associated with motion processing. The relatively unchanging characteristic of the study of MAEs has been the mode of measurement: duration continues to be used as an index of its strength, although measures of threshold elevation and nulling with computer-generated motions are becoming more prevalent. The MAE is a part of the armoury of motion phenomena employed to uncover the mysteries of vision. Over the last 150 years it has proved itself immensely adaptable to the shifts of fashion in visual science, and it is likely to continue in this vein.

scholarly journals A few remarks on stimulus power and interference in visual stimuli

2018 ◽  
Author(s):  
Bernt Skottun
Keyword(s):  
Fourier Transform ◽  
Visual Processing ◽  
Present Report ◽  
Visual Stimuli ◽  
Wavelet Coefficients ◽  
Physical Stimulus ◽  
Central Concept ◽  
The Fourier Transform

Interference may occur between visual stimuli or between separate elements in visual stimuli. Such interference takes place in the stimuli as these exist independently of vision and visual processing. Interference manifests itself in reduced ”stimulus power” which makes this a central concept in this context. The present report examines three potential measures of stimulus power: Amplitude sum, norm, and sum of the absolutes of wavelet coefficients. These are examined with very simple 1-Dimensional stimuli as examples. It is shown how there may be interference with each of these measures. Thus, interference is not only linked to the Fourier Transform. Due to interference a given stimulus may have less stimulus power when presented along with a second stimulus than when presented alone. This has consequences for the concept of stimulus sinceit makes it possible for the same physical stimulus to have different stimulus power in different contexts.

scholarly journals Choice-Related Activity during Visual Slant Discrimination in Macaque CIP but Not V3A

2018 ◽  
Author(s):  
L. Caitlin Elmore ◽  
Ari Rosenberg ◽  
Gregory C. DeAngelis ◽  
Dora E. Angelaki
Keyword(s):  
Visual Processing ◽  
Discrimination Task ◽  
Three Dimensional ◽  
Surface Orientation ◽  
Orientation Discrimination ◽  
Visual Orientation ◽  
Planar Surface ◽  
Related Activity ◽  
Planar Surfaces ◽  
3D Surface

AbstractCreating three-dimensional (3D) representations of the world from two-dimensional retinal images is fundamental to many visual guided behaviors including reaching and grasping. A critical component of this process is determining the 3D orientation of objects. Previous studies have shown that neurons in the caudal intraparietal area (CIP) of the macaque monkey represent 3D planar surface orientation (i.e., slant and tilt). Here we compare the responses of neurons in areas V3A (which is implicated in 3D visual processing and which precedes CIP in the visual hierarchy) and CIP to 3D oriented planar surfaces. We then examine whether activity in these areas correlates with perception during a fine slant discrimination task in which monkeys report if the top of a surface is slanted towards or away from them. Although we find that V3A and CIP neurons show similar sensitivity to planar surface orientation, significant choice-related activity during the slant discrimination task is rare in V3A but prominent in CIP. These results implicate both V3A and CIP in the representation of 3D surface orientation, and suggest a functional dissociation between the areas based on slant-related decision signals.Significance StatementSurface orientation perception is fundamental to visually guided behaviors such as reaching, grasping, and navigation. Previous studies implicate the caudal intraparietal area (CIP) in the representation of 3D surface orientation. Here we show that responses to 3D oriented planar surfaces are similar in CIP and V3A, which precedes CIP in the cortical hierarchy. However, we also find a qualitative distinction between the two areas: only CIP neurons show robust choice-related activity during a fine visual orientation discrimination task.

Off on the Wrong Foot: Local Features in Biological Motion

Perception ◽  
10.1068/p6140 ◽  
2009 ◽  
Vol 38 (4) ◽  
pp. 522-532 ◽  
Author(s):  
Daniel R Saunders ◽  
Julia Suchan ◽  
Nikolaus F Troje
Keyword(s):  
Motion Perception ◽  
Discrimination Task ◽  
Biological Motion ◽  
Large Body ◽  
Detection Task ◽  
Observer Performance ◽  
Local Motion ◽  
Motion Patterns ◽  
Direction Discrimination ◽  
Biological Motion Perception

Biological-motion perception consists of a number of different phenomena. They include global mechanisms that support the retrieval of the coherent shape of a walker, but also mechanisms which derive information from the local motion of its parts about facing direction and animacy, independent of the particular shape of the display. A large body of the literature on biological-motion perception is based on a synthetic stimulus generated by an algorithm published by James Cutting in 1978 ( Perception7 393–405). Here we show that this particular stimulus lacks a visual invariant inherent to the local motion of the feet of a natural walker, which in more realistic motion patterns indicates the facing direction of a walker independent of its shape. Comparing Cutting's walker to a walker derived from motion-captured data of real human walkers, we find no difference between the two displays in a detection task designed such that observers had to rely on global shape. In a direction discrimination task, however, in which only local motion was accessible to the observer, performance on Cutting's walker was at chance, while direction could still be retrieved from the stimuli derived from the real walker.

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