Tilt Aftereffect Research Articles

Tilt aftereffect following adaptation to translational Glass patterns.

Glass patterns (GPs) consist of randomly distributed dot pairs (dipoles) whose orientations are determined by specific geometric transforms. We assessed whether adaptation to stationary oriented translational GPs suppresses the activity of orientation selective detectors producing a tilt aftereffect (TAE). The results showed that adaptation to GPs produces a TAE similar to that reported in previous studies, though reduced in amplitude. This suggests the involvement of orientation selective mechanisms. We also measured the interocular transfer (IOT) of the GP-induced TAE and found an almost complete IOT, indicating the involvement of orientation selective and binocularly driven units. In additional experiments, we assessed the role of attention in TAE from GPs. The results showed that distraction during adaptation similarly modulates the TAE after adapting to both GPs and gratings. Moreover, in the case of GPs, distraction is likely to interfere with the adaptation process rather than with the spatial summation of local dipoles. We conclude that TAE from GPs possibly relies on visual processing levels in which the global orientation of GPs has been encoded by neurons that are mostly binocularly driven, orientation selective and whose adaptation-related neural activity is strongly modulated by attention.

Tilt representation beyond the retinotopic level

We perceive a stable visual world, which enables successful interaction with our environment, despite movements of the eyes, head, and body. How are such perceptions formed? One possibility is that retino-centric visual input is transformed into representations at higher levels, such as head-, body-, or world-centered representations. We investigated this hypothesis using the tilt aftereffect in a balanced adaptation paradigm designed to isolate head-, body-, and world-centered aftereffects. Observers adapted to two oppositely tilted stimuli, each contingent on one of two different gaze, head, or body directions. We found aftereffects contingent on gaze direction, but not head or body direction. This demonstrates that adaptable tilt representations exist in a head-centric frame but not in higher reference frames. These aftereffects may be attributed to adaptation of retinotopic tilt-sensitive neurons whose responses are modulated by gaze direction (gain fields). Such neurons could support functionally head-centric tilt representations and are found as early as V1. On the basis of our results we would not expect activity in tilt-sensitive neurons to be modulated by head or body direction. The balanced adaptation paradigm is a useful tool for examining properties of the process responsible for gaze modulation of activity in visual neurons.

Facial Expression Aftereffect Revealed by Adaption to Emotion-Invisible Dynamic Bubbled Faces.

Visual adaptation is a powerful tool to probe the short-term plasticity of the visual system. Adapting to local features such as the oriented lines can distort our judgment of subsequently presented lines, the tilt aftereffect. The tilt aftereffect is believed to be processed at the low-level of the visual cortex, such as V1. Adaptation to faces, on the other hand, can produce significant aftereffects in high-level traits such as identity, expression, and ethnicity. However, whether face adaptation necessitate awareness of face features is debatable. In the current study, we investigated whether facial expression aftereffects (FEAE) can be generated by partially visible faces. We first generated partially visible faces using the bubbles technique, in which the face was seen through randomly positioned circular apertures, and selected the bubbled faces for which the subjects were unable to identify happy or sad expressions. When the subjects adapted to static displays of these partial faces, no significant FEAE was found. However, when the subjects adapted to a dynamic video display of a series of different partial faces, a significant FEAE was observed. In both conditions, subjects could not identify facial expression in the individual adapting faces. These results suggest that our visual system is able to integrate unrecognizable partial faces over a short period of time and that the integrated percept affects our judgment on subsequently presented faces. We conclude that FEAE can be generated by partial face with little facial expression cues, implying that our cognitive system fills-in the missing parts during adaptation, or the subcortical structures are activated by the bubbled faces without conscious recognition of emotion during adaptation.

Tilt aftereffect due to adaptation to natural stimuli

The human visual system continuously adjusts to the current environment. To investigate these adjustments, biases in observers’ perceptions owing to changes in the visual environment are measured (visual aftereffects). Typically, the stimuli used are synthetic and are composed of oriented patterns such as lines or gratings. These patterns are known to activate individual neurons in the visual cortex, but cover only a small subset of actual visual stimulations. To overcome this drawback, recent research has focused on synthetic patterns that mimic several aspects of natural stimulation. However, the aftereffects of natural stimulation per-se remain largely unexplored. Here, we interleaved presentations of unmodified natural image adaptors, selected according to criteria favoring content at a particular orientation, with presentations of targets that test a perceived orientation. This allowed us to measure the change in the perceived orientation, namely the tilt aftereffect (TAE), which resulted from repeated image presentations. Results show a close to standard TAE with adaptor durations around 500ms, which is reduced with longer presentations. Importantly, our method can be generalized to investigate other aftereffects by selecting images differently.

Perceived illusory orientation from the flash grab effect induces the Tilt Aftereffect

PURPOSE: Tilt aftereffect (TAE) is the phenomenon that the perceived orientation of a test stimulus is altered after prolonged exposure to an oriented adaptor. This phenomenon has been widely considered to result from adaptation of orientation-selective neurons in the early visual cortex. In this study, we investigated whether the TAE could be induced from a perceived illusory orientation of adapting stimulus dissociated from its physical orientation, by taking advantage of a new illusion— the flash grab effect. METHODS: Subjects viewed a physically vertical line that was repeatedly and briefly flashed on top of a patterned disk that oscillated clockwise and counterclockwise, with the flashed line presented at the moment of the rotation reversals. Importantly the adapting line was perceived as tilted away from vertical. Following adaptation to 11 cycles of the flashed line, a test line was briefly presented near vertical orientation at the corresponding location without the background disk. RESULTS: Results showed that a significant TAE was induced by the perceived orientation. In contrast, when the physical orientation of the titled adapting line was adjust by each individual subject so that the adapting line was perceived to be vertical, no TAE was observed. Thus when perceived and physical orientations of the adapting lines are pitted against each other, the TAE is dependent on the perceived rather than the physical orientation. In separate experiments using multimodal neuroimaging methods, we have shown that the perceived tilt from flash grab effect is primarily due to feedback processing in the brain. CONCLUSIONS: Our results suggest that higher-level processes and feedback signals play an important role in the TAE.

Expectation and the tilt aftereffect

Expectation and the tilt aftereffect

Tilt Aftereffect due to Adaptation to Natural Images

Tilt Aftereffect due to Adaptation to Natural Images

Target selective tilt-after effect during texture learning

Target selective tilt-after effect during texture learning

Direct encoding of orientation variance in the visual system.

Our perception of regional irregularity, an example of which is orientation variance, seems effortless when we view two patches of texture that differ in this attribute. Little is understood, however, of how the visual system encodes a regional statistic like orientation variance, but there is some evidence to suggest that it is directly encoded by populations of neurons tuned broadly to high or low levels. The present study shows that selective adaptation to low or high levels of variance results in a perceptual aftereffect that shifts the perceived level of variance of a subsequently viewed texture in the direction away from that of the adapting stimulus (Experiments 1 and 2). Importantly, the effect is durable across changes in mean orientation, suggesting that the encoding of orientation variance is independent of global first moment orientation statistics (i.e., mean orientation). In Experiment 3 it was shown that the variance-specific aftereffect did not show signs of being encoded in a spatiotopic reference frame, similar to the equivalent aftereffect of adaptation to the first moment orientation statistic (the tilt aftereffect), which is represented in the primary visual cortex and exists only in retinotopic coordinates. Experiment 4 shows that a neuropsychological patient with damage to ventral areas of the cortex but spared intact early areas retains sensitivity to orientation variance. Together these results suggest that orientation variance is encoded directly by the visual system and possibly at an early cortical stage.

Contextual influence on the tilt after-effect in foveal and para-foveal vision

A sensory stimulus can only be properly interpreted in light of the stimuli that surround it in space and time. The tilt illusion (TI) and tilt after-effect (TAE) provide good evidence that the perception of a target depends strongly on both its spatial and temporal context. In previous studies, the TI and TAE have typically been investigated separately, so little is known about their co-effects on visual perception and information processing mechanisms. Here, we considered the influence of the spatial context and the temporal effect together and asked how center-surround context affects the TAE in foveal and para-foveal vision. Our results showed that different center-surround spatial patterns significantly affected the TAE for both foveal and para-foveal vision. In the fovea, the TAE was mainly produced by central adaptive gratings. Cross-oriented surroundings significantly inhibited the TAE, and iso-oriented surroundings slightly facilitated it; surround inhibition was much stronger than surround facilitation. In the para-fovea, the TAE was mainly decided by the surrounding patches. Likewise, a cross-oriented central patch inhibited the TAE, and an iso-oriented one facilitated it, but there was no significant difference between inhibition and facilitation. Our findings demonstrated, at the perceptual level, that our visual system adopts different mechanisms to process consistent or inconsistent central-surround orientation information and that the unequal magnitude of surround inhibition and facilitation is vitally important for the visual system to improve the detectability or discriminability of novel or incongruent stimuli.

Tilt after-effect from high spatial-frequency patterns in the amblyopic eye of adults with anisometropic amblyopia.

With abnormal visual cortical development, amblyopia is generally associated with high spatial frequency deficits in spatial vision. In this study, we aim to answer a critical question: How much high spatial frequency information is available to the amblyopic visual system? We measured the tilt after-effect following adaption to perceptually resolvable and unresolvable sinewave gratings, and showed that gratings with spatial frequency up to 1.5 times the cutoff frequency in grating orientation identification can still produce significant tilt after-effects in adults with amblyopia. Our results suggest that neural connections in the amblyopic visual cortex, at least in V1, may have profoundly developed to represent high spatial frequency information. The demonstration of extant neural connections for high spatial frequencies may have important implications for the development of training protocols for amblyopia treatment. Our paradigm may also serve as a non-invasive probe to diagnose the status of neural connections in other visual deficits.

Awareness shaping or shaped by prediction and postdiction: Editorial.

Awareness shaping or shaped by prediction and postdiction: Editorial.

Broad tuning of motion streak aftereffect reveals reciprocal gain interactions between orientation and motion neurons

Event Abstract Back to Event Broad tuning of motion streak aftereffect reveals reciprocal gain interactions between orientation and motion neurons Matthew Tang1*, J. Edwin Dickinson1, Troy Visser1 and David Badcock1 1 The University of Western Australia, Psychology, Australia The extended integration time of neurons leads to fast-moving objects producing neural orientation cues along the axis of motion. The current model [Geisler, W.S. (1999). Motion streaks provide a spatial code for motion direction. Nature, 400(6739), 65-69] argues that these orientation cues resolve direction ambiguity arising from the aperture problem, where the small size of receptive fields of neurons in V1 leads to direction uncertainty for contours that extend beyond their borders, by combining spatial orientation and motion signals in V1. We provide a comprehensive test of this model using a visual aftereffect, where adapting to a static grating causes the perceived direction of a subsequently-presented motion stimuli to be tilted away from the adapting orientation. Critically, a much broader range of orientations produced aftereffects than predicted by the current model, suggesting that orientation cues enter the motion system later in the processing sequence. Following this, we found that varying the spatial frequency of the adaptor changed the aftereffect from repulsive in perceived orientation to attractive for motion but not form stimuli. This is inconsistent with Geisler's model as the orientation selective neurons in V1 are spatial-frequency selective and provides evidence that motion streaks enter at V5, as this area integrates across spatial frequencies. We lastly manipulated V1 excitability using transcranial direct current stimulation that reduced the aftereffect, suggesting that the orientation cue is dependent upon V1. We provide a new computational model that accurately predicts our results in which motion streaks are detected by orientation-selective V1 neurons that exert gain onto motion-selective V5 neurons. Our model provides a new mechanism for form and motion interactions, leading to a number of unique predictions. Additionally, the differential spatial frequency effect is a new finding and has implications for models of motion processing. Keywords: Computational modelling, tDCS, Tilt aftereffect, motion streaks, form-motion interactions Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Sensation and Perception Citation: Tang M, Dickinson J, Visser T and Badcock D (2015). Broad tuning of motion streak aftereffect reveals reciprocal gain interactions between orientation and motion neurons. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00348 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Mr. Matthew Tang, The University of Western Australia, Psychology, Crawley, Australia, matthew.tang@uwa.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Matthew Tang J. Edwin Dickinson Troy Visser David Badcock Google Matthew Tang J. Edwin Dickinson Troy Visser David Badcock Google Scholar Matthew Tang J. Edwin Dickinson Troy Visser David Badcock PubMed Matthew Tang J. Edwin Dickinson Troy Visser David Badcock Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Surround-contingent tilt aftereffect.

We investigated whether aftereffects can be contingent on surroundings. Gabor patches tilted clockwise and counterclockwise were presented in alternation. Each patch was surrounded by an open circle or an open square. After prolonged exposure to these stimuli, tilt aftereffects were found to be contingent upon the surrounding frames: Vertical test patches appeared tilted clockwise when surrounded by the frame that was presented in conjunction with the adaptation patch tilted counterclockwise. The effect lasted 24 hours and was observed only when adaptation and test stimuli were presented at the same retinotopic position, but not observed at the same spatiotopic position. These results indicate that the aftereffect would be influenced not only by stimulus features but also by their surroundings.

Alterations to global but not local motion processing in long-term ecstasy (MDMA) users

Growing evidence indicates that the main psychoactive ingredient in the illegal drug "ecstasy" (methylendioxymethamphetamine) causes reduced activity in the serotonin and gamma-aminobutyric acid (GABA) systems in humans. On the basis of substantial serotonin input to the occipital lobe, recent research investigated visual processing in long-term users and found a larger magnitude of the tilt aftereffect, interpreted to reflect broadened orientation tuning bandwidths. Further research found higher orientation discrimination thresholds and reduced long-range interactions in the primary visual area of ecstasy users. The aim of the present research was to investigate whether serotonin-mediated V1 visual processing deficits in ecstasy users extend to motion processing mechanisms. Forty-five participants (21 controls, 24 drug users) completed two psychophysical studies: A direction discrimination study directly measured local motion processing in V1, while a motion coherence task tested global motion processing in area V5/MT. "Primary" ecstasy users (n = 18), those without substantial polydrug use, had significantly lower global motion thresholds than controls [p = 0.027, Cohen's d = 0.78 (large)], indicating increased sensitivity to global motion stimuli, but no difference in local motion processing (p = 0.365). These results extend on previous research investigating the long-term effects of illicit drugs on visual processing. Two possible explanations are explored: defuse attentional processes may be facilitating spatial pooling of motion signals in users. Alternatively, it may be that a GABA-mediated disruption to V5/MT processing is reducing spatial suppression and therefore improving global motion perception in ecstasy users.

Effects of attention on visible and invisible adapters.

It has been shown that attention can modulate the processing of a stimulus, even when it is invisible (Bahrami, Carmel, Walsh, Rees, & Lavie, 2008, Perception, 37, 1520-1528). Previous studies, however, investigated the effect of spatial attention on the processing of only invisible items. Thus, it remains unclear how the effect of spatial attention is distributed over visible and invisible items when these items are simultaneously attended at the same location. In the present study we addressed this question using two types of adapters, one visible and one invisible, and compared how attention affected the processing of each adapter. Moving gratings and tilted gratings were presented to each eye; the moving ones were dominant over the tilted ones. Both types of stimuli were located on the left and right sides of a fixation cross, and the participants performed a task that modulated their attention to one side or the other. In experiment 1 they were asked to detect the contrast decrement of one of the moving gratings, and in experiment 2 they detected a dot that was presented to both eyes. We found that attention increased the amount of motion aftereffects induced by the visible adapters. However, we did not find effects of attention on tilt aftereffects from the invisible adapters. Finally, in experiment 3 we found that attention successfully increased the amount of tilt aftereffects when the adapters were not suppressed. These findings suggest that spatial attention is more likely to influence visible items than invisible items in the same location. We also found that invisible items do not interfere with the attentional modulation of the processing of visible items.

Probing the neurochemical basis of synaesthesia using psychophysics

The neurochemical mechanisms that contribute to synaesthesia are poorly understood, but multiple models implicate serotonin and GABA in the development of this condition. Here we used psychophysical tasks to test the predictions that synaesthetes would display behavioral performance consistent with reduced GABA and elevated serotonin in primary visual cortex. Controls and synaesthetes completed the orientation-specific surround suppression (OSSS) and tilt-after effect (TAE) tasks, previously shown to relate to GABA and serotonin levels, respectively. Controls and synaesthetes did not differ in the performance parameter previously associated with GABA or in the magnitude of the TAE. However, synaesthetes did display lower contrast difference thresholds in the OSSS task than controls when no surround (NS) was present. These results are inconsistent with the hypothesized roles of GABA and serotonin in this condition, but provide preliminary evidence that synaesthetes exhibit enhanced contrast discrimination.

Line Orientation Adaptation: Local or Global?

Prolonged exposure to an oriented line shifts the perceived orientation of a subsequently observed line in the opposite direction, a phenomenon known as the tilt aftereffect (TAE). Here we consider whether the TAE for line stimuli is mediated by a mechanism that integrates the local parts of the line into a single global entity prior to the site of adaptation, or the result of the sum of local TAEs acting separately on the parts of the line. To test between these two alternatives we used the fact the TAE transfers almost completely across luminance contrast polarity [1]. We measured the TAE using adaptor and test lines that (1) either alternated in luminance polarity or were of a single polarity, and (2) either alternated in local orientation or were of a single orientation. We reasoned that if the TAE was agnostic to luminance polarity and was parts-based, we should obtain large TAEs using alternating-polarity adaptors with single-polarity tests. However we found that (i) TAEs using one-alternating-polarity adaptors with all-white tests were relatively small, increased slightly for two-alternating-polarity adaptors, and were largest with all-white or all-black adaptors. (ii) however TAEs were relatively large when the test was one-alternating polarity, irrespective of the adaptor type. (iii) The results with orientation closely mirrored those obtained with polarity with the difference that the TAE transfer across orthogonal orientations was weak. Taken together, our results demonstrate that the TAE for lines is mediated by a global shape mechanism that integrates the parts of lines into whole prior to the site of orientation adaptation. The asymmetry in the magnitude of TAE depending on whether the alternating-polarity lines was the adaptor or test can be explained by an imbalance in the population of neurons sensitive to 1st-and 2nd-order lines, with the 2nd-order lines being encoded by a subset of the mechanisms sensitive to 1st-order lines.

Tilt illusion and aftereffect from invisible flickering chromatic gratings

Tilt illusion and aftereffect from invisible flickering chromatic gratings

The company they keep: Background similarity influences transfer of aftereffects from second- to first-order stimuli

A wealth of studies has found that adapting to second-order visual stimuli has little effect on the perception of first-order stimuli. This is physiologically and psychologically troubling, since many cells show similar tuning to both classes of stimuli, and since adapting to first-order stimuli leads to aftereffects that do generalize to second-order stimuli. Focusing on high-level visual stimuli, we recently proposed the novel explanation that the lack of transfer arises partially from the characteristically different backgrounds of the two stimulus classes. Here, we consider the effect of stimulus backgrounds in the far more prevalent, lower-level, case of the orientation tilt aftereffect. Using a variety of first- and second-order oriented stimuli, we show that we could increase or decrease both within- and cross-class adaptation aftereffects by increasing or decreasing the similarity of the otherwise apparently uninteresting or irrelevant backgrounds of adapting and test patterns. Our results suggest that similarity between background statistics of the adapting and test stimuli contributes to low-level visual adaptation, and that these backgrounds are thus not discarded by visual processing but provide contextual modulation of adaptation. Null cross-adaptation aftereffects must also be interpreted cautiously. These findings reduce the apparent inconsistency between psychophysical and neurophysiological data about first- and second-order stimuli.