Shifts Of Visual Attention Research Articles

Correlated variability and its attentional modulation depend on anatomical connectivity

Visual cortical neurons show variability in their responses to repeated presentations of a stimulus and a portion of this variability is shared across neurons. Attention may enhance visual perception by reducing shared spiking variability. However, shared variability and its attentional modulation are not consistent within or across cortical areas, and depend on additional factors such as neuronal type. A critical factor that has not been tested is actual anatomical connectivity. We measured spike count correlations among pairs of simultaneously recorded neurons in the primary visual cortex (V1) for which anatomical connectivity was inferred from spiking cross-correlations. Neurons were recorded in monkeys performing a contrast-change discrimination task requiring covert shifts in visual spatial attention. Accordingly, spike count correlations were compared across trials in which attention was directed toward or away from the visual stimulus overlapping recorded neuronal receptive fields. Consistent with prior findings, attention did not significantly alter spike count correlations among random pairings of unconnected V1 neurons. However, V1 neurons connected via excitatory synapses showed a significant reduction in spike count correlations with attention. Interestingly, V1 neurons connected via inhibitory synapses demonstrated high spike count correlations overall that were not modulated by attention. Correlated variability in excitatory circuits also depended upon neuronal tuning for contrast, the task-relevant stimulus feature. These results indicate that shared variability depends on the type of connectivity in neuronal circuits. Also, attention significantly reduces shared variability in excitatory circuits, even when attention effects on randomly sampled neurons within the same area are weak.

Spatial Decoding for Gaze Independent Brain-Computer Interface Based on Covert Visual Attention Shift Using Electroencephalography.

The gaze-independent brain-computer interface (BCI) device is used to re-establish interaction for individuals who have abnormal eye movement. It may be possible to control the BCI by shifting your attention spatially. However, spatial attention is rarely employed to increase the effectiveness of target detection and is typically used to provide a simple "yes" or "no" response to the target recognition inquiry. To improve the effectiveness of detecting target, it is crucial to take advantage of the possible advantages of spatial attention. N2-posterior-contralateral (N2pc) component reflects correlates of visual spatial attention and is used to determine target position. In this study, a long-short-term memory (LSTM) network is used to answer "yes/no" questions by decoding covert spatial attention based on N2pc characteristics using EEG signals. The proposed LSTM-based model's average decoding accuracy is 92.79%. The target detection efficiency was successfully increased by about 4% when compared to conventional machine learning algorithms. The proposed model is tested on the independent dataset to validate its performance. The results of this work show that N2pc characteristics can be employed in gaze-independent BCIs for tracking covert attention shifts, which may help persons with poor eye mobility to connect with their environment.

Crowding expands and is less sensitive to target-flanker differences during a shift of visual attention

Target-flanker similarity and critical spacing control visual crowding when attention is pre-allocated, but these have not been studied when attention shifts. Flanked target Gabors appeared 8° left and right of central fixation throughout each 1.5 s trial. Subjects reported target Gabor tilt. In Expt. 1, target blinks increased accuracy, and flanker blinks decreased it, but only when attention shifted left or right from a central RSVP cue, hardly before it, indicating an exogenous/endogenous synergy. Whether parallel or orthogonal, flankers of the same wavelength as the target crowded substantially. Parallel half-wavelength flankers also crowded, but orthogonal half-wavelength ones did not. In Expt. 2, crowding when attention shifts was the same for targets and flankers within Bouma’s bound (2.5° apart) as outside it (5.0° apart.) In Expt. 3, Bouma’s bound was restored when attention was focused continuously on the target. We conclude that crowding temporarily expands and becomes less discriminative when attention shifts.

The role of habitual learning in premotor attention allocation.

Dual-task studies have demonstrated that goal-directed actions are typically preceded by a premotor shift of visual attention toward the movement goal location. This finding is often taken as evidence for an obligatory coupling between attention and motor preparation. Here, we examined whether this coupling entails a habitual component relating to an expectation of spatial congruence between visual and motor targets. In two experiments, participants had to identify a visual discrimination target (DT) while preparing variably delayed pointing movements to a motor target (MT). To induce distinct expectations regarding the DT position, different groups of participants performed a training phase in which the DT either always appeared at MT, opposite to MT, or at an unpredictable position. In a subsequent test phase, the DT position was randomized to assess the impact of learned expectancy on premotor attention allocation. Although we applied individually determined DT presentation times in the test phase of Experiment 1, a fixed DT presentation time was used in Experiment 2. Both experiments yielded evidence for attentional enhancement at the expected DT position. Although interpretability of this effect was limited in Experiment 1 because of between-group differences in DT presentation time, results of Experiment 2 were much clearer. Specifically, a marked discrimination benefit was observed at the position opposite to MT in participants anticipating the DT at this position, whereas no statistically significant benefit was found at MT. Crucially, this was observed at short movement delays, demonstrating that expectation of spatial incongruence between visual and motor targets allows for decoupling of attentional resources from ongoing motor preparation. Based on our findings, we suggest that premotor attention shifts entail a considerable habitual component rather than being the sole result of motor programming.

The normalization model predicts responses during object-based attention in the human visual cortex.

Divisive normalization of the neural responses by the activity of the neighboring neurons has been proposed as a fundamental operation in the nervous system based on its success in predicting neural responses recorded in primate electrophysiology studies. Nevertheless, experimental evidence for the existence of this operation in the human brain is still scant. Here, using functional MRI, we explored the role of normalization across the visual hierarchy in the human visual cortex. Using stimuli form the two categories of human bodies and houses, we presented objects in isolation or in clutter and asked participants to attend or ignore the stimuli. Focusing on the primary visual area V1, the object-selective regions LO and pFs, the body-selective region EBA, and the scene-selective region PPA, we first modeled single-voxel responses using a weighted sum, a weighted average, and a normalization model and demonstrated that although the weighted sum and weighted average models also made acceptable predictions in some conditions, the response to multiple stimuli could generally be better described by a model that takes normalization into account. We then explored the observed effects of attention on cortical responses and demonstrated that these effects were predicted by the normalization model, but not by the weighted sum or the weighted average models. Our results thus provide evidence that the normalization model can predict responses to objects across shifts of visual attention, suggesting the role of normalization as a fundamental operation in the human brain.

A cortical zoom-in operation underlies covert shifts of visual spatial attention

Shifting the focus of attention without moving the eyes poses challenges for signal coding in visual cortex in terms of spatial resolution, signal routing, and cross-talk. Little is known how these problems are solved during focus shifts. Here, we analyze the spatiotemporal dynamic of neuromagnetic activity in human visual cortex as a function of the size and number of focus shifts in visual search. We find that large shifts elicit activity modulations progressing from highest (IT) through mid-level (V4) to lowest hierarchical levels (V1). Smaller shifts cause those modulations to start at lower levels in the hierarchy. Successive shifts involve repeated backward progressions through the hierarchy. We conclude that covert focus shifts arise from a cortical coarse-to-fine process progressing from retinotopic areas with larger toward areas with smaller receptive fields. This process localizes the target and increases the spatial resolution of selection, which resolves the above issues of cortical coding.

Presaccadic attention sharpens visual acuity

Visual perception is limited by spatial resolution, the ability to discriminate fine details. Spatial resolution not only declines with eccentricity but also differs for polar angle locations around the visual field, also known as ‘performance fields'. To compensate for poor peripheral resolution, we make rapid eye movements—saccades—to bring peripheral objects into high-acuity foveal vision. Already before saccade onset, visual attention shifts to the saccade target location and prioritizes visual processing. This presaccadic shift of attention improves performance in many visual tasks, but whether it changes resolution is unknown. Here, we investigated whether presaccadic attention sharpens peripheral spatial resolution; and if so, whether such effect interacts with performance fields asymmetries. We measured acuity thresholds in an orientation discrimination task during fixation and saccade preparation around the visual field. The results revealed that presaccadic attention sharpens acuity, which can facilitate a smooth transition from peripheral to foveal representation. This acuity enhancement is similar across the four cardinal locations; thus, the typically robust effect of presaccadic attention does not change polar angle differences in resolution.

Processing spatial configurations in visuospatial working memory is influenced by shifts of overt visual attention.

When memorizing multiple objects, humans process them in relation to each other, proposing a configuration benefit. Shifts in overt visual attention through eye movements might influence the processing of spatial configurations. Whereas some research suggests that overt visual attention aids the processing of spatial representations, other research suggests a snapshot-like processing of spatial configurations, thus likely not relying on eye movements. In the first experiment, we focused on the comparison between an enforced fixation and a free view condition regarding configurational effects. Participants encoded objects' locations and were asked for changes at retrieval. One object was displaced in half of the trials and was either accompanied by a configuration or was displayed alone. In the second experiment, we expanded this idea by enforcing fixation during different task phases, namely encoding, maintenance and retrieval. We investigated if a fixed gaze during one specific phase drives the influence of eye movements when processing spatial configurations. We observed reliable configuration benefits for the free view conditions. Whereas a fixed gaze throughout the whole trial reduced the effect, enforced fixations during the task phases did not break the configuration benefit. Our findings suggest that whereas the processing of spatial configurations in memory is supported by the ability of performing shifts of overt visual attention, configurational processing does not rely on these shifts occurring throughout the task. Our results indicate a reciprocal relationship of visuospatial working memory and eye movements.

Trait Anxiety Influences Negative Affect-modulated Distribution of Visuospatial Attention

Visuospatial attention allows humans to selectively gate and prioritize visual (including salient, emotional) information for efficiently navigating natural visual environments. As emotions have been known to influence attentional performance, we asked if emotions also modulate the spatial distribution of visual attention and whether any such effect was further associated with individual differences in anxiety. Participants (n = 28) discriminated the orientation of target Gabor patches co-presented with distractors, speedily and accurately. The key manipulation was randomly presenting a task-irrelevant face emotion prime briefly (50 ms), conveying Neutral/Disgust/Scrambled (Null) emotion signal 150 ms preceding the target patches. We calculated attention gradient (change in negative inverse attentional efficiency with unit change in distance from the source of emotion signal) as a metric to answer our questions. Specifically, the Disgust signal modulated the direction of attention gradients differentially in individuals with varying degrees of trait - anxiety, such that the gradients correlated negatively with individual trait-anxiety scores. This implies spatial shifts in Disgust-signalled visual attention with varying trait - anxiety levels. Neutral yielded attention gradients comparable to Scrambled, implying no specific effect of this signal and there was no association with anxiety levels in both. No correlation was observed between state - anxiety and the emotion-cued attention gradients. In sum, the results suggest that individual trait - anxiety levels influence the effect of negative and physiologically arousing emotion signals (e.g., Disgust) on the spatial distribution of visual attention. The findings could be of relevance for understanding biases in visual behaviour underlying affective states and disorders.

Metacognition tracks sensitivity following involuntary shifts of visual attention

Salient, exogenous cues have been shown to induce a temporary boost of perceptual sensitivity in their immediate vicinity. In two experiments involving uninformative exogenous cues presented at various times before a target stimulus, we investigated whether human observers (N = 100) were able to monitor the involuntary increase in performance induced by such transients. We found that an increase of perceptual sensitivity (in a choice task) and encoding precision (in a free-estimation task) occurred approximately 100 ms after cue onset, and was accompanied by an increase in confidence about the perceptual response. These simultaneous changes in sensitivity and confidence resulted in stable metacognition across conditions. These results suggest that metacognition efficiently tracks the effects of a reflexive attentional mechanism known to evade voluntary control, and illustrate a striking ability of high-level cognition to capture fleeting, low-level sensory modulations.

Spatial selectivity in adaptation to gaze direction.

A person's focus of attention is conveyed by the direction of their eyes and face, providing a simple visual cue fundamental to social interaction. A growing body of research examines the visual mechanisms that encode the direction of another person's gaze as we observe them. Here we investigate the spatial receptive field properties of these mechanisms, by testing the spatial selectivity of sensory adaptation to gaze direction. Human observers were adapted to faces with averted gaze presented in one visual hemifield, then tested in their perception of gaze direction for faces presented in the same or opposite hemifield. Adaptation caused strong, repulsive perceptual aftereffects, but only for faces presented in the same hemifield as the adapter. This occurred even though adapting and test stimuli were in the same external location across saccades. Hence, there was clear evidence for retinotopic adaptation and a relative lack of either spatiotopic or spatially invariant adaptation. These results indicate that adaptable representations of gaze direction in the human visual system have retinotopic spatial receptive fields. This strategy of coding others' direction of gaze with positional specificity relative to one's own eye position may facilitate key functions of gaze perception, such as socially cued shifts in visual attention.

Time to Pay Attention? Information Search Explains Amplified Framing Effects Under Time Pressure

Decades of research have established the ubiquity and importance of choice biases, such as the framing effect, yet why these seemingly irrational behaviors occur remains unknown. A prominent dual-system account maintains that alternate framings bias choices because of the unchecked influence of quick, affective processes, and findings that time pressure increases the framing effect have provided compelling support. Here, we present a novel alternative account of magnified framing biases under time pressure that emphasizes shifts in early visual attention and strategic adaptations in the decision-making process. In a preregistered direct replication (N = 40 adult undergraduates), we found that time constraints produced strong shifts in visual attention toward reward-predictive cues that, when combined with truncated information search, amplified the framing effect. Our results suggest that an attention-guided, strategic information-sampling process may be sufficient to explain prior results and raise challenges for using time pressure to support some dual-system accounts.

Visual attention during pediatric resuscitation with feedback devices: a randomized simulation study

BackgroundThe aim of this study was to investigate the effect of feedback devices on visual attention and the quality of pediatric resuscitation.MethodsThis was a randomized cross-over simulation study at the Medical University of Vienna. Participants were students and neonatal providers performing four resuscitation scenarios with the support of feedback devices randomized. The primary outcome was the quality of resuscitation. Secondary outcomes were total dwell time (=total duration of visit time) on areas of interest and the workload of participants.ResultsForty participants were analyzed. Overall, chest compression (P < 0.001) and ventilation quality were significantly better (P = 0.002) when using a feedback device. Dwell time on the feedback device was 40.1% in the ventilation feedback condition and 48.7% in the chest compression feedback condition. In both conditions, participants significantly reduced attention from the infant’s chest and mask (72.9 vs. 32.6% and 21.9 vs. 12.7%). Participants’ subjective workload increased by 3.5% (P = 0.018) and 8% (P < 0.001) when provided with feedback during a 3-min chest compression and ventilation scenario, respectively.ConclusionsThe quality of pediatric resuscitation significantly improved when using real-time feedback. However, attention shifted from the manikin and other equipment to the feedback device and subjective workload increased, respectively.ImpactCardiopulmonary resuscitation with feedback devices results in a higher quality of resuscitation and has the potential to lead to a better outcome for patients.Feedback devices consume attention from resuscitation providers.Feedback devices were associated with a shift of visual attention to the feedback devices and an increased workload of participants.Increased workload for providers and benefits for resuscitation quality need to be balanced for the best effect.

Attention differentially modulates multiunit activity in the lateral geniculate nucleus and V1 of macaque monkeys.

Attention promotes the selection of behaviorally relevant sensory signals from the barrage of sensory information available. Visual attention modulates the gain of neuronal activity in all visual brain areas examined, although magnitudes of gain modulations vary across areas. For example, attention gain magnitudes in the dorsal lateral geniculate nucleus (LGN) and primary visual cortex (V1) vary tremendously across fMRI measurements in humans and electrophysiological recordings in behaving monkeys. We sought to determine whether these discrepancies are due simply to differences in species or measurement, or more nuanced properties unique to each visual brain area. We also explored whether robust and consistent attention effects, comparable to those measured in humans with fMRI, are observable in the LGN or V1 of monkeys. We measured attentional modulation of multiunit activity in the LGN and V1 of macaque monkeys engaged in a contrast change detection task requiring shifts in covert visual spatial attention. Rigorous analyses of LGN and V1 multiunit activity revealed robust and consistent attentional facilitation throughout V1, with magnitudes comparable to those observed with fMRI. Interestingly, attentional modulation in the LGN was consistently negligible. These findings demonstrate that discrepancies in attention effects are not simply due to species or measurement differences. We also examined whether attention effects correlated with the feature selectivity of recorded multiunits. Distinct relationships suggest that attentional modulation of multiunit activity depends upon the unique structure and function of visual brain areas.

Visual attention prediction for Autism Spectrum Disorder with hierarchical semantic fusion

Visual attention for the diagnosis of Autism Spectrum Disorder (ASD) which is a kind of mental disorder has attracted the interests of increasing number of researchers. Although multiple visual attention prediction models have been proposed, this problem is still open. In this paper, considering the shift of visual attention, we propose that an image can be viewed as a pseudo sequence. Besides, we propose a novel visual attention prediction method for ASD with hierarchical semantic fusion (ASD-HSF). Specifically, the proposed model mainly contains a Spatial Feature Module (SFM) and a Pseudo Sequential Feature Module (PSFM). SFM is designed to extract spatial semantic features with a fully convolutional network, while PSFM implemented by two Convolutional Long Short-Term Memory networks (ConvLSTMs) is applied to learn pseudo sequential features. And the outputs of these two modules are fused to extract the final saliency map which simultaneously includes spatial semantic information and pseudo sequential information. Experimental results show that the proposed model not only outperforms ten state-of-the-art general saliency prediction counterparts, but also reaches the first and the second ranks under four metrics and the rest ones of ASD saliency prediction respectively.

Individual differences in first-pass fixation duration in reading are related to resting-state functional connectivity

Although there are considerable individual differences in eye movements during text reading, their neural correlates remain unclear. In this study, we investigated the relationship between the first-pass fixation duration (FPFD) in natural reading and resting-state functional connectivity (RSFC) in the brain. We defined the brain regions associated with early visual processing, word identification, attention shifts, and oculomotor control as seed regions. The results showed that individual FPFDs were positively correlated with individual RSFCs between the early visual network, visual word form area, and eye movement control/dorsal attention network. Our findings provide new evidence on the neural correlates of eye movements in text reading and indicate that individual differences in fixation time may shape the RSFC differences in the brain through the time-on-task effect and the mechanism of Hebbian learning.

Eye movement performance and clinical outcomes among female athletes post-concussion

ABSTRACT Background Most post-concussion eye movement (EM) research involves predominantly male samples. We evaluated pro- (PRO; reflexive shift of visual attention to target) and anti- (ANTI; executive control of visual attention away from target) computer-based saccade task performance among female, collegiate athletes with recent concussion (CON) versus healthy-control athletes (HC). We evaluated the relationship between EM performance and post-concussion outcomes. We hypothesized ANTI performance would differ among CON and HC due to greater executive control demands, and that EM performance (both tasks) would be associated with clinical outcomes in CON. Methods 16 CON (assessed 4–10 days post-injury [M = 6.87, SD = 2.15 days]) and 16 age-matched HC athletes were recruited. General linear mixed modeling and Pearson’s correlations were used. Results On ANTI, CON demonstrated higher error rate [F(1,2863) = 12.650, p<.001] and shorter latency on error trials [F(1,469) = 5.976, p=.015] relative to HC. Multiple EM measures were associated with clinical outcomes: PRO duration predicted days to symptom remission (r=.44, p <.05); ANTI error rate was associated with symptom burden on the day of testing (r=.27, p <.05). Conclusion This study demonstrates promising utility of EM measures to detect cognitive control and sensorimotor effects of concussion among female athletes and their use as a prognostic indicators of recovery.

Depth-aware salient object segmentation

Depth-aware salient object segmentation

Gravitational models explain shifts on human visual attention

Visual attention refers to the human brain’s ability to select relevant sensory information for preferential processing, improving performance in visual and cognitive tasks. It proceeds in two phases. One in which visual feature maps are acquired and processed in parallel. Another where the information from these maps is merged in order to select a single location to be attended for further and more complex computations and reasoning. Its computational description is challenging, especially if the temporal dynamics of the process are taken into account. Numerous methods to estimate saliency have been proposed in the last 3 decades. They achieve almost perfect performance in estimating saliency at the pixel level, but the way they generate shifts in visual attention fully depends on winner-take-all (WTA) circuitry. WTA is implemented by the biological hardware in order to select a location with maximum saliency, towards which to direct overt attention. In this paper we propose a gravitational model to describe the attentional shifts. Every single feature acts as an attractor and the shifts are the result of the joint effects of the attractors. In the current framework, the assumption of a single, centralized saliency map is no longer necessary, though still plausible. Quantitative results on two large image datasets show that this model predicts shifts more accurately than winner-take-all.

Visual attention and eye movement control during oculomotor competition.

Saccadic eye movements are typically preceded by selective shifts of visual attention. Recent evidence, however, suggests that oculomotor selection can occur in the absence of attentional selection when saccades erroneously land in between nearby competing objects (saccade averaging). This study combined a saccade task with a visual discrimination task to investigate saccade target selection during episodes of competition between a saccade target and a nearby distractor. We manipulated the spatial predictability of target and distractor locations and asked participants to execute saccades upon variably delayed go-signals. This allowed us to systematically investigate the capacity to exert top-down eye movement control (as reflected in saccade endpoints) based on the spatiotemporal dynamics of visual attention during movement preparation (measured as visual sensitivity). Our data demonstrate that the predictability of target and distractor locations, despite not affecting the deployment of visual attention prior to movement preparation, largely improved the accuracy of short-latency saccades. Under spatial uncertainty, a short go-signal delay likewise enhanced saccade accuracy substantially, which was associated with a more selective deployment of attentional resources to the saccade target. Moreover, we observed a systematic relationship between the deployment of visual attention and saccade accuracy, with visual discrimination performance being significantly enhanced at the saccade target relative to the distractor only before the execution of saccades accurately landing at the saccade target. Our results provide novel insights linking top-down eye movement control to the operation of selective visual attention during movement preparation.