Unattended Locations Research Articles

Task-irrelevant inputs alter ensemble representations of faces within the spatial focus of attention.

Spatial attention enhances processing of information, but how does unattended and task-irrelevant information influence visual processing within the spatial focus of attention? We tested this by asking participants to extract the average emotional expression of a set of sequentially presented faces while simultaneously presenting task-irrelevant faces at a spatially unattended and task-irrelevant location. Across several experiments, we found that participants' reports of the emotional expression of faces at the attended location were biased toward the task-irrelevant faces. For example, when happier faces were presented at the unattended location, participants were biased to perceive the attended faces as happier. A control experiment in which participants were asked to also detect probes at cued and uncued locations showed that spatial attention was directed towards the cued location as instructed. Together, these results reveal that unattended and task-irrelevant inputs do not only affect the efficiency of target processing, for example by slowing responses or lowering accuracies, but that they can systematically bias ensemble representations within the spatial focus of attention. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Differential neural mechanisms underlie cortical gating of visual spatial attention mediated by alpha-band oscillations

Selective attention relies on neural mechanisms that facilitate processing of behaviorally relevant sensory information while suppressing irrelevant information, consistently linked to alpha-band oscillations in human M/EEG studies. We analyzed cortical alpha responses from intracranial electrodes implanted in eight epilepsy patients, who performed a visual spatial attention task. Electrocorticographic data revealed a spatiotemporal dissociation between attention-modulated alpha desynchronization, associated with the enhancement of sensory processing, and alpha synchronization, associated with the suppression of sensory processing, during the cue-target interval. Dorsal intraparietal areas contralateral to the attended hemifield primarily exhibited a delayed and sustained alpha desynchronization, while ventrolateral extrastriatal areas ipsilateral to the attended hemifield primarily exhibited an earlier and sustained alpha synchronization. Analyses of cross-frequency coupling between alpha phase and broadband high-frequency activity (HFA) further revealed cross-frequency interactions along the visual hierarchy contralateral to the attended locations. Directionality analyses indicate that alpha phase in early and extrastriatal visual areas modulated HFA power in downstream visual areas, thus potentially facilitating the feedforward processing of an upcoming, spatially predictable target. In contrast, in areas ipsilateral to the attended locations, HFA power modulated local alpha phase in early and extrastriatal visual areas, with suppressed interareal interactions, potentially attenuating the processing of distractors. Our findings reveal divergent alpha-mediated neural mechanisms underlying target enhancement and distractor suppression during the deployment of spatial attention, reflecting enhanced functional connectivity at attended locations, while suppressed functional connectivity at unattended locations. The collective dynamics of these alpha-mediated neural mechanisms play complementary roles in the efficient gating of sensory information.

The time course of feature-selective attention inside and outside the focus of spatial attention

Research on attentional selection of stimulus features has yielded seemingly contradictory results. On the one hand, many experiments in humans and animals have observed a "global" facilitation of attended features across the entire visual field, even when spatial attention is focused on a single location. On the other hand, several event-related potential studies in humans reported that attended features are enhanced at the attended location only. The present experiment demonstrates that these conflicting results can be explained by differences in the timing of attentional allocation inside and outside the spatial focus of attention. Participants attended to fields of either red or blue randomly moving dots on either the left or right side of fixation with the task of detecting brief coherent motion targets. Recordings of steady-state visual evoked potentials elicited by the flickering stimuli allowed concurrent measurement of the time course of feature-selective attention in visual cortex on both the attended and the unattended sides. The onset of feature-selective attentional modulation on the attended side occurred around 150 ms earlier than on the unattended side. This finding that feature-selective attention is not spatially global from the outset but extends to unattended locations after a temporal delay resolves previous contradictions between studies finding global versus hierarchical selection of features and provides insight into the fundamental relationship between feature-based and location-based (spatial) attention mechanisms.

A biometric and physically unclonable function–Based authentication protocol for payload exchanges in internet of drones

Internet of Drones (IoD) has been deployed in numerous military and civilian domains to offer services such as target surveillance, traffic monitoring, disaster handling and environmental monitoring. However, message exchanges among the drones and ground station servers are via insecure wireless channels. In addition, drones may be deployed in hostile and unattended locations. This renders the IoD susceptible to numerous privacy and security threats such as drone capture and cloning. Therefore, many security solutions have been developed based on techniques such as blockchain and public key infrastructure. However, majority of these schemes are still susceptible to many attacks while some of them are inefficient for the resource-limited IoD devices. In this paper, a Physically Unclonable Function (PUF) challenge-response and biometric based robust authentication protocol is presented. Its formal security is carried out using the Real or Random (RoR) model, which demonstrates the robustness of the negotiated session key. In addition, its semantic analysis shows that it can withstand typical IoD attacks such as impersonation, replay, de-synchronization and spoofing. In terms of performance, it is shown to incur lower computation, energy and communication costs.

Collaborative relay for achieving long-term and low-AoI data collection in UAV-aided IoT systems

In Internet of Things (IoT) systems, sensor nodes are frequently placed in remote and unattended locations to monitor environmental data. One significant challenge is ensuring the timely and efficient transmission of data generated by these sensor nodes back to the base station. The use of unmanned aerial vehicles (UAVs) can provide a practical solution to this challenge by acting as mobile relay nodes for facilitating data transmission. In most existing works, UAVs are typically restricted to collecting data within their designated areas and returning to the base station for data offloading, resulting in suboptimal data timeliness due to long-distance flights. A limited number of works have explored the utilization of relay collaboration by UAVs for data collection, enabling efficient and immediate transmission of sensor node data to the base station. Nevertheless, UAVs positioned at significant distances from the base station face challenges in obtaining timely energy replenishment. This makes them unable to effectively support long-duration data collection missions. In order to tackle these challenges, we develop a UAV-aided IoT collaborative data collection mechanism and propose a matching games-based data collection (MGDC) scheme. In this scheme, we begin by identifying convergence nodes within the ground sensor network, responsible for uploading sensor-generated data to passing UAVs. Furthermore, we divide the mission area into multiple subareas based on the number of available UAVs. Subsequently, using a matching game algorithm, we establish relay relationships between UAVs to enable efficient relay transmissions among paired UAVs. To achieve efficient data collection of UAVs, we employ an improved adaptive large neighborhood search (IALNS) algorithm for UAV flight path planning. Finally, we incorporate an alternating charging mode to ensure all UAVs have the opportunity to return to the base station for energy recharge. Through comprehensive experimentation, we confirm the significant enhancement provided by our proposed data collection scheme compared to existing schemes. This scheme effectively reduces system age of information (AoI) and extends the runtime of the system.

Costs and benefits of voluntary attention in crows.

Behavioural signatures of voluntary, endogenous selective attention have been found in both mammals and birds, but the relationship between performance benefits at attended and costs at unattended locations remains unclear. We trained two carrion crows (Corvus corone) on a Posner-like spatial cueing task with dissociated cue and target locations, using both highly predictive and neutral central cues to compare reaction time (RT) and detection accuracy for validly, invalidly and neutrally cued targets. We found robust RT effects of predictive cueing at varying stimulus-onset asynchronies (SOA) that resulted from both advantages at cued locations and costs at un-cued locations. Both crows showed cueing effects around 15-25 ms with an early onset at 100 ms SOA, comparable to macaques. Our results provide a direct assessment of costs and benefits of voluntary attention in a bird species. They show that crows are able to guide spatial attention using associative cues, and that the processing advantage at attended locations impairs performance at unattended locations.

Probabilistic visual attentional guidance triggers "feature avoidance" response errors.

Spatial attention affects not only where we look, but also what we perceive and remember in attended and unattended locations. Previous work has shown that manipulating attention via top-down cues or bottom-up capture leads to characteristic patterns of feature errors. Here we investigated whether experience-driven attentional guidance-and probabilistic attentional guidance more generally-leads to similar feature errors. We conducted a series of pre-registered experiments employing a learned spatial probability or probabilistic pre-cue; all experiments involved reporting the color of one of four simultaneously presented stimuli using a continuous response modality. When the probabilistic cues guided attention to an invalid (nontarget) location, participants were less likely to report the target color, as expected. But strikingly, their errors tended to be clustered around a nontarget color opposite the color of the invalidly-cued nontarget. This "feature avoidance" was found for both experience-driven and top-down probabilistic cues, and appears to be the product of a strategic-but possibly subconscious-behavior, occurring when information about the features and/or feature-location bindings outside the focus of attention is limited. The findings emphasize the importance of considering how different types of attentional guidance can exert different effects on feature perception and memory reports. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Challenging the fixed-criterion model of perceptual decision-making.

Perceptual decision-making is often conceptualized as the process of comparing an internal decision variable to a categorical boundary or criterion. How the mind sets such a criterion has been studied from at least two perspectives. One idea is that the criterion is a fixed quantity. In work on subjective phenomenology, the notion of a fixed criterion has been proposed to explain a phenomenon called "subjective inflation"-a form of metacognitive mismatch in which observers overestimate the quality of their sensory representation in the periphery or at unattended locations. A contrasting view emerging from studies of perceptual decision-making is that the criterion adjusts to the level sensory uncertainty and is thus sensitive to variations in attention. Here, we mathematically demonstrate that previous empirical findings supporting subjective inflation are consistent with either a fixed or a flexible decision criterion. We further lay out specific task properties that are necessary to make inferences about the flexibility of the criterion: (i) a clear mapping from decision variable space to stimulus feature space and (ii) an incentive for observers to adjust their decision criterion as uncertainty changes. Recent work satisfying these requirements has demonstrated that decision criteria flexibly adjust according to uncertainty. We conclude that the fixed-criterion model of subjective inflation is poorly tenable.

Transcranial magnetic stimulation to frontal but not occipital cortex disrupts endogenous attention

Covert endogenous (voluntary) attention improves visual performance. Human neuroimaging studies suggest that the putative human homolog of macaque frontal eye fields (FEF+) is critical for this improvement, whereas early visual areas are not. Yet, correlational MRI methods do not manipulate brain function. We investigated whether rFEF+ or V1/V2 plays a causal role in endogenous attention. We used transcranial magnetic stimulation (TMS) to alter activity in the visual cortex or rFEF+ when observers performed an orientation discrimination task while attention was manipulated. On every trial, they received double-pulse TMS at a predetermined site (stimulated region) around V1/V2 or rFEF+. Two cortically magnified gratings were presented, one in the stimulated region (contralateral to the stimulated area) and another in the symmetric (ipsilateral) nonstimulated region. Grating contrast was varied to measure contrast response functions (CRFs) for all attention and stimulation combinations. In experiment 1, the CRFs were similar at the stimulated and nonstimulated regions, indicating that early visual areas do not modulate endogenous attention during stimulus presentation. In contrast, occipital TMS eliminates exogenous (involuntary) attention effects on performance [A. Fernández, M.Carrasco,Curr. Biol.30, 4078-4084 (2020)]. In experiment 2, rFEF+ stimulation decreased the overall attentional effect; neither benefits at the attended location nor costs at the unattended location were significant. The frequency and directionality of microsaccades mimicked this pattern: Whereas occipital stimulation did not affect microsaccades, rFEF+ stimulation caused a higher microsaccade rate directed toward the stimulated hemifield. These results provide causal evidence of the role of this frontal region for endogenous attention.

Pre-saccadic attention relies more on suppression than does covert attention.

During covert and pre-saccadic attentional shifts, it is unclear how facilitation and suppression processes interact for target selection. A recent countermanding task pointed to greater suppression at unattended locations during trials with saccades compared to trials without saccades (i.e., fixation and successful stop trials), whereas target facilitation did not differ. It is unknown whether this finding is restricted to countermanding paradigms that involve inhibitory processes. To test this, we adapted Gaspelin and colleagues (2015)'s attention capture task where, within the same block, one location was primed with frequent line discrimination trials, and all locations were occasionally probed using letters report trials. Participants also performed a baseline condition without priming. We tested 15 participants and examined how performance at non-primed locations was affected by covert versus pre-saccadic attention in blocks of four or six items, as well as by position from the primed location and timing from saccade onset. For both attention conditions, letter report at non-primed locations was worse compared to baseline, demonstrating suppression, and letter report at primed location was better, demonstrating facilitation. In saccades trials, letter report was better at primed locations and worse at non-primed locations compared to fixation trials. The timing of this additional pre-saccadic suppression differed from saccadic suppression. In both attention conditions, suppression was greater when primed and non-primed locations were within the same hemifield or in diagonal opposite quadrants. These results confirmed that attention preceding saccade execution suppressed non-primed locations to a larger extent than covert attention, with the same spatial quadrant effect.

Dissociable effects of attention and expectation on perceptual sensitivity to action-outcomes

Self-generated sensations evoke attenuated neural response - physiological attenuation - and is perceived with less intensity - perceptual attenuation. This phenomenon is referred as sensory attenuation and is proposed to reflect the silencing of predicted sensations. The present study aimed to investigate the independent contribution of expectation and attention on sensory attenuation. The expectation associated with the stimulus feature and the focus of attention was manipulated independently by orthogonal cues. We found pronounced sensory attenuation at the unattended location when the stimulus was self-generated (Experiment 1). When the stimulus was externally-generated (Experiment 2), sensory attenuation was observed at the attended location. Sensory attenuation of expected action-outcome was not observed when the attention cue was uninformative (Experiment 3A). The findings corroborate the claim from Bayesian models that attention mediates sensory attenuation. The results also highlight the paradoxes in Bayesian proposals of perception–action interaction.

Optimizing lifetime of a wireless sensor network covering moving targets

In this article, the problems studied are to optimize the life of the network of sensors covering mobile targets by minimizing the energy consumption of the network. Indeed, wireless sensor networks have received particular attention in recent years, as their applications are common today, such as vehicle tracking or battlefield monitoring. In a wireless sensor network, the sensor battery plays an important role. The function of the sensor depends on the battery life. Replacement of batteries becomes impossible once deployed in a remote or unattended location. A set of randomly placed sensors monitors targets moving in an area. Each sensor has a limited lifetime and two states: Active or Inactive. An active sensor can monitor targets in its monitoring sub-area at a necessary energy consumption cost. To model these problems, we use a mathematical model based on linear programming with mixed integer variables. AMPL is used to formulate the model and MINOS for its resolution and the numerical results allowed to obtain an adequate activation scheduling of the sensors by improving their lifetime.

Spectral Distribution Dynamics across Different Attentional Priority States.

Anticipatory covert spatial attention improves performance on tests of visual detection and discrimination, and shifts are accompanied by decreases and increases of α band power at electroencephalography (EEG) electrodes corresponding to the attended and unattended location, respectively. Although the increase at the unattended location is often interpreted as an active mechanism (e.g., inhibiting processing at the unattended location), most experiments cannot rule out the alternative possibility that it is a secondary consequence of selection elsewhere. To adjudicate between these accounts, we designed a Posner-style visual cueing task in which male and female human participants made orientation judgments of targets appearing at one of four locations: up, down, right, or left. Critically, trials were blocked such that within a block the locations along one meridian alternated in status between attended and unattended, and targets never appeared at the other two, making them irrelevant. Analyses of the concurrently measured EEG signal were conducted on "traditional" narrowband α (8-14 Hz), as well as on two components resulting from the decomposition of this signal: "periodic" α; and the slope of the aperiodic 1/f-like component. Although data from right-left blocks replicated the familiar pattern of lateralized asymmetry in narrowband α power, with neither α signal could we find evidence for any difference in the time course at unattended versus irrelevant locations, an outcome consistent with the secondary-consequence interpretation of attention-related dynamics in the α band. Additionally, 1/f slope was shallower at attended and unattended locations, relative to irrelevant, suggesting a tonic adjustment of physiological state.SIGNIFICANCE STATEMENT Visual spatial attention, the prioritization of one location in the visual field, is critical for guiding behavior in cluttered environments. Although influential theories posit an important role for α band oscillations in the inhibition of processing at unattended locations, we used a novel procedure to find evidence for an alternative interpretation: selection of one location may simply result in a return to physiological baseline at all others. In addition to determining one way that attention does not work (important for future progress in this field), we also discovered novel evidence for one way that it does work: by modifying the tonic physiological state (indexed by an aperiodic component of the electroencephalography (EEG)] at locations where spatial selection is likely to occur.

Inhibition of Return in Visual Search Does Not Rely on Spatial Working Memory.

Inhibition of return (IOR) prevents the immediate reorientation to previously attended locations, such that unattended locations are prioritized. In the current study, we were interested in whether saccadic IOR is affected by the storage of visuospatial information in working memory (WM) during a visual search task. To this end, participants searched a display for a target letter once while holding no, two, or four object locations in their spatial WM. During the search, either a previously inspected or an uninspected item was probed, and the participants were instructed to immediately saccade to this probed item before resuming the search. The results showed that saccadic latencies to previously inspected items were longer than to uninspected items, indicating the presence of IOR during the search. However, this effect was observed regardless of the number of item locations held in the spatial WM. This finding suggests that saccadic IOR does not rely on visuospatial WM in visual search.

A Review Article on Energy Efficient Routing Protocol for Minimizing Energy Consumption

Abstract: Recent developments in the area of micro-sensor devices have accelerated advances in the sensor networks field leading to many new protocols specifically designed for wireless sensor networks (WSNs). Wireless sensor networks with hundreds to thousands of sensor nodes can gather information from an unattended location and transmit the gathered data to a particular user, depending on the application. These sensor nodes have some constraints due to their limited energy, storage capacity and computing power. Data are routed from one node to other using different routing protocols. There are a number of routing protocols for wireless sensor networks. In this review article, we discuss the architecture of wireless sensor networks. Further, we categorize the routing protocols according to some key factors and summarize their mode of operation. Finally, we provide a comparative study on these various protocols. Keywords: Wireless Sensor Network, TEEN protocol, isolated node

Intermediate, Wholistic Shape Representation in Object Recognition: A Pre-Attentive Stage of Processing?

Evidence is presented for intermediate, wholistic visual representations of objects and non-objects that are computed online and independent of visual attention. Short-term visual priming was examined between visually similar shapes, with targets either falling at the (valid) location cued by primes or at another (invalid) location. Object decision latencies were facilitated when the overall shapes of the stimuli were similar irrespective of whether the location of the prime was valid or invalid, with the effects being equally large for object and non-object targets. In addition, the effects were based on the overall outlines of the stimuli and low spatial frequency components, not on local parts. In conclusion, wholistic shape representations based on outline form, are rapidly computed online during object recognition. Moreover, activation of common wholistic shape representations prime the processing of subsequent objects and non-objects irrespective of whether they appear at attended or unattended locations. Rapid derivation of wholistic form provides a key intermediate stage of object recognition.

To Grasp the World at a Glance: The Role of Attention in Visual and Semantic Associative Processing.

Associative relations among words, concepts and percepts are the core building blocks of high-level cognition. When viewing the world ‘at a glance’, the associative relations between objects in a scene, or between an object and its visual background, are extracted rapidly. The extent to which such relational processing requires attentional capacity, however, has been heavily disputed over the years. In the present manuscript, I review studies investigating scene–object and object–object associative processing. I then present a series of studies in which I assessed the necessity of spatial attention to various types of visual–semantic relations within a scene. Importantly, in all studies, the spatial and temporal aspects of visual attention were tightly controlled in an attempt to minimize unintentional attention shifts from ‘attended’ to ‘unattended’ regions. Pairs of stimuli—either objects, scenes or a scene and an object—were briefly presented on each trial, while participants were asked to detect a pre-defined target category (e.g., an animal, a nonsense shape). Response times (RTs) to the target detection task were registered when visual attention spanned both stimuli in a pair vs. when attention was focused on only one of two stimuli. Among non-prioritized stimuli that were not defined as to-be-detected targets, findings consistently demonstrated rapid associative processing when stimuli were fully attended, i.e., shorter RTs to associated than unassociated pairs. Focusing attention on a single stimulus only, however, largely impaired this relational processing. Notably, prioritized targets continued to affect performance even when positioned at an unattended location, and their associative relations with the attended items were well processed and analyzed. Our findings portray an important dissociation between unattended task-irrelevant and task-relevant items: while the former require spatial attentional resources in order to be linked to stimuli positioned inside the attentional focus, the latter may influence high-level recognition and associative processes via feature-based attentional mechanisms that are largely independent of spatial attention.

Metacognitive blindness in temporal selection during the deployment of spatial attention

How does orienting attention in space affect the quality of our confidence judgments? Orienting attention to a particular location is known to boost visual performance, but the deployment of attention is far from being instantaneous. Whether observers are able to monitor the time needed for attention to deploy remains largely unknown. To address this question, we adapted a “Wundt clocks” paradigm, asking observers (N=140) to reproduce the phase of a rotating clock at the time of an attentional cue, and to evaluate their confidence in their responses. Attention affected the latency between objective and perceived events: the average reported phase was delayed in accordance with the known latencies of voluntary and involuntary attention. Yet, we found that confidence remains oblivious to these attention-induced perceptual delays, like a ‘metacognitive blind spot’. In addition, we observed weaker metacognition specifically during the deployment of voluntary attention, suggesting a tight relationship between the attentional and metacognitive systems. While previous work has considered how visual confidence adjusts to fully attended versus unattended locations, our study demonstrates that the very process of orienting attention in space can alter metacognition.

Transient perceptual enhancements resulting from selective shifts of exogenous attention in the central fovea

Exogenous attention, a powerful adaptive tool that quickly and involuntarily orients processing resources to salient stimuli, has traditionally been studied in the lower-resolution parafoveal and peripheral visual field.1-4 It is not known whether and how it operates across the 1° central fovea where visual resolution peaks.5,6 Here we investigated the dynamics of exogenous attention in the foveola. To circumvent the challenges posed by fixational eye movements at this scale, we used high-precision eye-tracking and gaze-contingent display control for retinal stabilization.7 High-acuity stimuli were briefly presented foveally at varying delays following an exogenous cue. Attended and unattended locations were just a few arcminutes away from the preferred locus of fixation. Our results show that for short temporal delays, observers' ability to discriminate fine detail is enhanced at the cued location. This enhancement is highly localized and does not extend to the nearby locations only 16' away. On a longer timescale, instead, we report an inverse effect: paradoxically, acuity is sharper at the unattended locations, resembling the phenomenon of inhibition of return at much larger eccentricities.8-10 Although exogenous attention represents a mechanism for low-cost monitoring of the environment in the extrafoveal space, these findings show that, in the foveola, it transiently modulates vision of detail with a high degree of resolution. Together with inhibition of return, it may aid visual exploration of complex foveal stimuli.11.

The Impact of Shape-Based Cue Discriminability on Attentional Performance.

With rapidly developing technology, visual cues became a powerful tool for deliberate guiding of attention and affecting human performance. Using cues to manipulate attention introduces a trade-off between increased performance in cued, and decreased in not cued, locations. For higher efficacy of visual cues designed to purposely direct user’s attention, it is important to know how manipulation of cue properties affects attention. In this verification study, we addressed how varying cue complexity impacts the allocation of spatial endogenous covert attention in space and time. To gradually vary cue complexity, the discriminability of the cue was systematically modulated using a shape-based design. Performance was compared in attended and unattended locations in an orientation-discrimination task. We evaluated additional temporal costs due to processing of a more complex cue by comparing performance at two different inter-stimulus intervals. From preliminary data, attention scaled with cue discriminability, even for supra-threshold cue discriminability. Furthermore, individual cue processing times partly impacted performance for the most complex, but not simpler cues. We conclude that, first, cue complexity expressed by discriminability modulates endogenous covert attention at supra-threshold cue discriminability levels, with increasing benefits and decreasing costs; second, it is important to consider the temporal processing costs of complex visual cues.