Bayesian analysis on missing visual information and object complexity on visual search for object orientation and object identity.

Missing visual information, such as a gap between an object or an occluded view, has been shown to disrupt visual search and make amodal completion inefficient. Previous research, using simple black bars as stimuli, failed to show a pop-out effect (flat search slope across increasing visual set sizes) during a feature search when the target was partially occluded, but not in cases where it was fully visible. We wanted to see if this lack of a pop-out effect during feature (orientation) search extended to complex objects (Experiment 1) and identity search (Experiment 2). Participants completed orientation and identity visual search tasks by deciding whether the target was present or not present. Bayesian analyses was conducted to find evidence for observed data to be under the null (pop-out effects) or alternative hypotheses (differences in search slopes). When no occluders or gaps were present, a pop-out effect occurred when searching for a simple objects' orientation or identity. In addition, object complexity affected identity search, with anecdotal evidence suggesting that some complex object may not show a pop-out effect. Furthermore, white occluding bars were more disruptive than having a gap of visual information for feature search but not for identity search. Overall, pop-out effects do occur for simple objects, but when the task is more difficult, search for real-world objects is greatly affected by any type of visual disruption.

Eye-tracking to examine differences in alcohol product appeal by sex among young people.

Background: Advertising of traditional alcopops contains elements that appeal to youth, especially females. Supersized alcopops are marketed differently than traditional alcopops and contain up to 5.5 standard alcoholic drinks. Young females are more likely to underestimate the alcohol content of supersized alcopops, putting them at higher risk of overconsumption. Similar to supersized alcopops, beer is packaged in large cans and in the same areas of store shelves.Objective: This study examined among young people whether supersized alcopops versus beer products disproportionately appealed to females.Methods: Eleven adolescents (13-17 years old) and 72 college students (21-26 years old) were recruited during 2019-2020. Participants viewed 19 photos of convenience store display cases containing both supersized alcopop and beer products. While viewing each image, participants were instructed to click on the beverage that looked the "coolest" (i.e. most appealing). Eye-tracking hardware and software measured the amount of time participants visually fixated on each product. Participants completed a survey to record demographic characteristics.Results: Compared to males (n=25), females (n=58) fixated on supersized alcopops for 6.8 seconds longer (95%CI 0.3,13.3). Females also had 3.7 times the odds of selecting a supersized alcopop as the product they found most appealing compared to males (95%CI 1.68,8.01), adjusting for amount of time visually fixating on supersized alcopops, which was also a significant predictor.Conclusions: Young females' strong preference for supersized alcopops is concerning given they disproportionately underestimate their potency, relative to males, and are more likely to obtain dangerously high BAC levels from consuming one or two supersized alcopops.

Prolonging the Response Movement Reduces Commission Errors in a High-Go, Low-No-Go Target Detection Task and Composite Metrics of Performance Miss This Effect.

OBJECTIVE: Expand research on the Sustained Attention to Response Task (SART) to a more applied agricultural target detection/selection task and examine the utility of various performance metrics, including composite measures of speed and accuracy, in a High-Go/Low-No-Go stimuli task. BACKGROUND: Modified SARTs have been utilized to investigate mechanisms, such as failures of response inhibition, occurring in friendly fire and collateral damage incidents. Researchers have demonstrated that composite measures of speed and accuracy are useful for Low Go/High No-Go stimuli tasks, but this has not been demonstrated for High-Go/Low-No-Go tasks, such as the SART. METHOD: Participants performed a modified SART, where they selected ("sprayed") images of weeds (Go stimuli) that appeared on a computer screen, while withholding to rarer soybean plant images (No-Go stimuli). RESULTS: Response time was a function of distance from a central starting point. Participants committed commission errors (sprayed the soybeans) at a significantly higher rate when the stimuli appeared under the cursor centered on the screen for each trial. Participant's omission errors (failure to spray a weed) increased significantly as a function of distance. The composite measures examined were primarily influenced by response time and omission errors limiting their utility when commission errors are of particular interest. CONCLUSION: Participants are far more accurate in their decision making when required to execute a longer duration motor task in High-Go/Low-No-Go experiments. APPLICATION: Demonstrates a serious human factors liability of target detection and snap-to-target systems.

Vesicle shape transformations driven by confined active filaments.

In active matter systems, deformable boundaries provide a mechanism to organize internal active stresses. To study a minimal model of such a system, we perform particle-based simulations of an elastic vesicle containing a collection of polar active filaments. The interplay between the active stress organization due to interparticle interactions and that due to the deformability of the confinement leads to a variety of filament spatiotemporal organizations that have not been observed in bulk systems or under rigid confinement, including highly-aligned rings and caps. In turn, these filament assemblies drive dramatic and tunable transformations of the vesicle shape and its dynamics. We present simple scaling models that reveal the mechanisms underlying these emergent behaviors and yield design principles for engineering active materials with targeted shape dynamics.

Topological structure and dynamics of three-dimensional active nematics.

Topological structures are effective descriptors of the nonequilibrium dynamics of diverse many-body systems. For example, motile, point-like topological defects capture the salient features of two-dimensional active liquid crystals composed of energy-consuming anisotropic units. We dispersed force-generating microtubule bundles in a passive colloidal liquid crystal to form a three-dimensional active nematic. Light-sheet microscopy revealed the temporal evolution of the millimeter-scale structure of these active nematics with single-bundle resolution. The primary topological excitations are extended, charge-neutral disclination loops that undergo complex dynamics and recombination events. Our work suggests a framework for analyzing the nonequilibrium dynamics of bulk anisotropic systems as diverse as driven complex fluids, active metamaterials, biological tissues, and collections of robots or organisms.

The temporal and spatial constraints of saccade planning to double-step target displacements.

The double-step paradigm investigates the characteristics of planning and execution when the motor system must rapidly adjust for a new goal location. Studies have provided detailed temporal information based on the duration available for the motor system to prepare a new movement trajectory (here referred to as re-preparation time). However, previous work has largely examined single displacement sizes, limiting the spatiotemporal understanding of movement planning and execution. The lack of a description of this behavioral timecourse across increasing displacement sizes is true for saccades, rapid eye movements that redirect the fovea. Furthermore, during the double-step paradigm, the primary saccade often fails to accurately foveate the final target location and a secondary saccade brings the target onto the fovea. However, it is also unknown how this compensation is concurrently modified with the exposure duration and displacement of the movement goal. Here, we examined the amount of time required to change the initial saccade direction to a new target location for relatively small (20°, 30°, and 40°) and large (60° and 90°) target spatial separations. Interestingly, we found a clear relationship between the saccade direction and the amount of time allowed to redirect the movement; across separations, intermediate saccades occurred when approximately 60-140 ms was available to readjust the movement plan. Additionally, there was a consistent relationship between the timing of the secondary saccade and the re-preparation time across jump sizes, suggesting that concurrent movement correction planning was dependent on the amount of exposure to the final movement goal.

Saccadic eye movements smear spatial working memory.

Why do saccades interfere with spatial working memory? One possibility is that attention and saccades are tightly coupled, and performing a saccade momentarily removes attention from spatial working memory, degrading the memory representation. This cannot be the entire explanation, because saccades cause greater interference than do covert attentional shifts (Lawrence, Myerson, & Abrams, 2004). In addition, this saccadic degradation is limited to spatial but not object, configural, or verbal representations. We propose that saccadic remapping is partially responsible for this increased interference. To test this, we used a spatial change detection task, and during the retention interval, participants either performed a central task, a peripheral task without an eye movement, or a peripheral task that required a saccade. Using the method of constant stimuli allowed us to fit psychophysical functions in which we derived measures of spatial memory precision, guessing, and response bias. It is important that we found a directionally specific loss of memory precision, such that memory representations were less precise along the axis of the saccade. This was beyond the general loss of precision we found for covert shifts, suggesting that part of the effect is because of remapping. Saccades also increased guessing, but unlike the loss of precision, the effect was nondirectional. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Angioembolization is necessary with any volume of contrast extravasation in blunt trauma.

INTRODUCTION: Reduction of nonessential angiogram and embolization for patients sustaining blunt abdominal and pelvic trauma would allow improved utilization and decreased morbidity related to nontherapeutic embolization. We hypothesized that the nature of intravenous contrast extravasation (IVCE) on computed tomography (CT) would be directly related to the finding of extravasation on angiogram and need for embolization. METHODS: A 5-year retrospective evaluation of trauma patients with IVCE on CT. Demographics, hemodynamics, and IVCE location and maximal dimension/volume were examined for relationship to IVCE on angiography and need for embolization. Primary complications were defined as nephropathy and acute respiratory distress syndrome. RESULTS: A total of 128 patients were identified with IVCE on CT. Ninety-seven (75.8%) also had IVCE identified on angiography requiring some form of embolization. The size of IVCE on CT was not related to IVCE on angiogram (P = 0.69). Location of IVCE was related to need for embolization, with spleen embolization (85.4%) being much more frequent than liver (51.5%, P = 0.006). Complication rate was 8.7% in all patients, and was not different between patients undergoing embolization and those who did not (P = 0.40). CONCLUSION: IVCE volume was not predictive of continued bleeding and need for embolization. However, splenic injuries with IVCE required embolization more frequently. In contrast, liver injuries were found to have infrequent on-going IVCE on angiography. Complications associated with angiogram with or without embolization are infrequent, and CT findings may not be predictive of ongoing bleeding. We do not recommend selective exclusion of patients from angiographic evaluation when a blush is present.

Averted body postures facilitate orienting of the eyes.

It is well established that certain social cues, such as averted eye gaze, can automatically initiate the orienting of another's spatial attention. However, whether human posture can also reflexively cue spatial attention remains unclear. The present study directly investigated whether averted neutral postures reflexively cue the attention of observers in a normal population of college students. Similar to classic gaze-cuing paradigms, non-predictive averted posture stimuli were presented prior to the onset of a peripheral target stimulus at one of five SOAs (100ms-500ms). Participants were instructed to move their eyes to the target as fast as possible. Eye-tracking data revealed that participants were significantly faster in initiating saccades when the posture direction was congruent with the target stimulus. Since covert attention shifts precede overt shifts in an obligatory fashion, this suggests that directional postures reflexively orient the attention of others. In line with previous work on gaze-cueing, the congruency effect of posture cue was maximal at the 300ms SOA. These results support the notion that a variety of social cues are used by the human visual system in determining the "direction of attention" of others, and also suggest that human body postures are salient stimuli capable of automatically shifting an observer's attention.

Neural activity reveals perceptual grouping in working memory.

There is extensive evidence that the contralateral delay activity (CDA), a scalp recorded event-related brain potential, provides a reliable index of the number of objects held in visual working memory. Here we present evidence that the CDA not only indexes visual object working memory, but also the number of locations held in spatial working memory. In addition, we demonstrate that the CDA can be predictably modulated by the type of encoding strategy employed. When individual locations were held in working memory, the pattern of CDA modulation mimicked previous findings for visual object working memory. Specifically, CDA amplitude increased monotonically until working memory capacity was reached. However, when participants were instructed to group individual locations to form a constellation, the CDA was prolonged and reached an asymptote at two locations. This result provides neural evidence for the formation of a unitary representation of multiple spatial locations.

Evidence from the eyes: Threatening postures hold attention.

Efficient detection of threat provides obvious survival advantages and has resulted in a fast and accurate threat-detection system. Although beneficial under normal circumstances, this system may become hypersensitive and cause threat-processing abnormalities. Past research has shown that anxious individuals have difficulty disengaging attention from threatening faces, but it is unknown whether other forms of threatening social stimuli also influence attentional orienting. Much like faces, human body postures are salient social stimuli, because they are informative of one's emotional state and next likely action. Additionally, postures can convey such information in situations in which another's facial expression is not easily visible. Here we investigated whether there is a threat-specific effect for high-anxious individuals, by measuring the time that it takes the eyes to leave the attended stimulus, a task-irrelevant body posture. The results showed that relative to nonthreating postures, threat-related postures hold attention in anxious individuals, providing further evidence of an anxiety-related attentional bias for threatening information. This is the first study to demonstrate that attentional disengagement from threatening postures is affected by emotional valence in those reporting anxiety.

Watch out! Directional threat-related postures cue attention and the eyes.

Previous work indicates that threatening facial expressions with averted eye gaze can act as a signal of imminent danger, enhancing attentional orienting in the gazed-at direction. However, this threat-related gaze-cueing effect is only present in individuals reporting high levels of anxiety. The present study used eye tracking to investigate whether additional directional social cues, such as averted angry and fearful human body postures, not only cue attention, but also the eyes. The data show that although body direction did not predict target location, anxious individuals made faster eye movements when fearful or angry postures were facing towards (congruent condition) rather than away (incongruent condition) from peripheral targets. Our results provide evidence for attentional cueing in response to threat-related directional body postures in those with anxiety. This suggests that for such individuals, attention is guided by threatening social stimuli in ways that can influence and bias eye movement behaviour.

Reducing the Disruptive Effects of Interruptions With Noninvasive Brain Stimulation.

OBJECTIVE: The authors determine whether transcranial direct current stimulation (tDCS) can reduce resumption time when an ongoing task is interrupted. BACKGROUND: Interruptions are common and disruptive. Working memory capacity has been shown to predict resumption lag (i.e., time to successfully resume a task after interruption). Given that tDCS applied to brain areas associated with working memory can enhance performance, tDCS has the potential to improve resumption lag when a task is interrupted. METHOD: Participants were randomly assigned to one of four groups that received anodal (active) stimulation of 2 mA tDCS to one of two target brain regions, left and right dorsolateral prefrontal cortex (DLPFC), or to one of two control areas, active stimulation of the left primary motor cortex or sham stimulation of the right DLPFC, while completing a financial management task that was intermittently interrupted with math problem solving. RESULTS: Anodal stimulation to the right and left DLPFC significantly reduced resumption lags compared to the control conditions (sham and left motor cortex stimulation). Additionally, there was no speed-accuracy tradeoff (i.e., the improvement in resumption time was not accompanied by an increased error rate). CONCLUSION: Noninvasive brain stimulation can significantly decrease resumption lag (improve performance) after a task is interrupted. APPLICATION: Noninvasive brain stimulation offers an easy-to-apply tool that can significantly improve interrupted task performance.

The effect of saccade metrics on the corollary discharge contribution to perceived eye location.

Corollary discharge (CD) is hypothesized to provide the movement information (direction and amplitude) required to compensate for the saccade-induced disruptions to visual input. Here, we investigated to what extent these conveyed metrics influence perceptual stability in human subjects with a target-displacement detection task. Subjects made saccades to targets located at different amplitudes (4°, 6°, or 8°) and directions (horizontal or vertical). During the saccade, the target disappeared and then reappeared at a shifted location either in the same direction or opposite to the movement vector. Subjects reported the target displacement direction, and from these reports we determined the perceptual threshold for shift detection and estimate of target location. Our results indicate that the thresholds for all amplitudes and directions generally scaled with saccade amplitude. Additionally, subjects on average produced hypometric saccades with an estimated CD gain <1. Finally, we examined the contribution of different error signals to perceptual performance, the saccade error (movement-to-movement variability in saccade amplitude) and visual error (distance between the fovea and the shifted target location). Perceptual judgment was not influenced by the fluctuations in movement amplitude, and performance was largely the same across movement directions for different magnitudes of visual error. Importantly, subjects reported the correct direction of target displacement above chance level for very small visual errors (<0.75°), even when these errors were opposite the target-shift direction. Collectively, these results suggest that the CD-based compensatory mechanisms for visual disruptions are highly accurate and comparable for saccades with different metrics.

Enhancing multiple object tracking performance with noninvasive brain stimulation: a causal role for the anterior intraparietal sulcus.

Multiple object tracking (MOT) is a complex task recruiting a distributed network of brain regions. There are also marked individual differences in MOT performance. A positive causal relationship between the anterior intraparietal sulcus (AIPS), an integral region in the MOT attention network and inter-individual variation in MOT performance has not been previously established. The present study used transcranial direct current stimulation (tDCS), a form of non-invasive brain stimulation, in order to examine such a causal link. Active anodal stimulation was applied to the right AIPS and the left dorsolateral prefrontal cortex (DLPFC) (and sham stimulation), an area associated with working memory (but not MOT) while participants completed a MOT task. Stimulation to the right AIPS significantly improved MOT accuracy more than the other two conditions. The results confirm a causal role of the AIPS in the MOT task and illustrate that tDCS has the ability to improve MOT performance.

What we remember affects how we see: spatial working memory steers saccade programming.

Relationships between visual attention, saccade programming, and visual working memory have been hypothesized for over a decade. Awh, Jonides, and Reuter-Lorenz (Journal of Experimental Psychology: Human Perception and Performance 24(3):780-90, 1998) and Awh et al. (Psychological Science 10(5):433-437, 1999) proposed that rehearsing a location in memory also leads to enhanced attentional processing at that location. In regard to eye movements, Belopolsky and Theeuwes (Attention, Perception & Psychophysics 71(3):620-631, 2009) found that holding a location in working memory affects saccade programming, albeit negatively. In three experiments, we attempted to replicate the findings of Belopolsky and Theeuwes (Attention, Perception & Psychophysics 71(3):620-631, 2009) and determine whether the spatial memory effect can occur in other saccade-cuing paradigms, including endogenous central arrow cues and exogenous irrelevant singletons. In the first experiment, our results were the opposite of those in Belopolsky and Theeuwes (Attention, Perception & Psychophysics 71(3):620-631, 2009), in that we found facilitation (shorter saccade latencies) instead of inhibition when the saccade target matched the region in spatial working memory. In Experiment 2, we sought to determine whether the spatial working memory effect would generalize to other endogenous cuing tasks, such as a central arrow that pointed to one of six possible peripheral locations. As in Experiment 1, we found that saccade programming was facilitated when the cued location coincided with the saccade target. In Experiment 3, we explored how spatial memory interacts with other types of cues, such as a peripheral color singleton target or irrelevant onset. In both cases, the eyes were more likely to go to either singleton when it coincided with the location held in spatial working memory. On the basis of these results, we conclude that spatial working memory and saccade programming are likely to share common overlapping circuitry.

The interaction between memorized objects and abrupt onsets in oculomotor capture.

Recent evidence has been found for a source of task-irrelevant oculomotor capture (defined as when a salient event draws the eyes away from a primary task) that originates from working memory. An object memorized for a nonsearch task can capture the eyes during search. Here, an experiment was conducted that generated interactions between the presence of a memorized object (a colored disk) with the abrupt onset of a new object during visual search. The goal was to compare memory-driven oculomotor capture to oculomotor capture caused by an abrupt onset. This has implications for saccade programming theories, which have little to say about saccades that are influenced by object working memory. Results showed that memorized objects capture the eyes at nearly the same rate as abrupt onsets. When the abrupt onset and a memorized color coincide in the same object, this combination leads to even greater oculomotor capture. Finally, latencies support the competitive integration model: Shorter saccade latencies were found when the memorized color combined with the onset captured the eyes, as compared to either color or onset only. Longer latencies were also found when the color and onset occurred in the same display but were spatially separated.

Visual working memory capacity for objects from different categories: a face-specific maintenance effect.

The capacity of visual working memory was examined when complex objects from different categories were remembered. Previous studies have not examined how visual similarity affects object memory, though it has long been known that similar-sounding phonological information interferes with rehearsal in auditory working memory. Here, experiments required memory for two or four objects. Memory capacity was compared between remembering four objects from a single object category to remembering four objects from two different categories. Two-category sets led to increased memory capacity only when upright faces were included. Capacity for face-only sets never exceeded their nonface counterparts, and the advantage for two-category sets when faces were one of the categories disappeared when inverted faces were used. These results suggest that two-category sets which include faces are advantaged in working memory but that faces alone do not lead to a memory capacity advantage.

Implicit learning for probable changes in a visual change detection task.

Previous research demonstrates that implicitly learned probability information can guide visual attention. We examined whether the probability of an object changing can be implicitly learned and then used to improve change detection performance. In a series of six experiments, participants completed 120-130 training change detection trials. In four of the experiments the object that changed color was the same shape (trained shape) on every trial. Participants were not explicitly aware of this change probability manipulation and change detection performance was not improved for the trained shape versus untrained shapes. In two of the experiments, the object that changed color was always in the same general location (trained location). Although participants were not explicitly aware of the change probability, implicit knowledge of it did improve change detection performance in the trained location. These results indicate that improved change detection performance through implicitly learned change probability occurs for location but not shape.

Transfer effects in task-set cost and dual-task cost after dual-task training in older and younger adults: further evidence for cognitive plasticity in attentional control in late adulthood.

Older adults' difficulties in performing two tasks concurrently have been well documented (Kramer & Madden, 2008). It has been observed that the age-related differences in dual-task performance are larger when the two tasks require similar motor responses (2001) and that in some conditions older adults also show greater susceptibility than younger adults to input interference (Hein & Schubert, 2004). The authors recently observed that even when the two tasks require motor responses, both older and younger adults can learn to perform a visual discrimination task and an auditory discrimination task faster and more accurately (Bherer et al., 2005). In the present study, the authors extended this finding to a dual-task condition that involves two visual tasks requiring two motor responses. Older and younger adults completed a dual-task training program in which continuous individualized adaptive feedback was provided to enhance performance. The results indicate that, even with similar motor responses and two visual stimuli, both older and younger adults showed substantial gains in performance after training and that the improvement generalized to new task combinations involving new stimuli. These results suggest that dual-task skills can be substantially improved in older adults and that cognitive plasticity in attentional control is still possible in old age.