Typicality modulates the visual awareness of objects.

In the present study, we assessed whether typicality can influence the visual awareness of objects. Participants tracked moving images of objects and counted how often members of one category bounced off the edges of the display. On the last trial, an unexpected object moved across the display. In our first two experiments, this object could belong to the same category as the tracked or untracked objects. While participants were more likely to notice atypical members of the untracked category, this pattern of results reversed when participants tracked atypical objects. In our last two experiments, the unexpected object could belong to the same category as the tracked objects or a new category of objects. In this case, participants were more likely to notice typical members of both the tracked category and the new category. Together, these findings suggest that typicality can modulate the visual awareness of objects.

When detecting a salient target makes search more effortful.

Prior research has demonstrated two distinct modes of searching a display: singleton detection mode and feature search mode. Due to the explicit template-based attentional control involved in feature search mode, singleton detection mode is often assumed to be less mentally effortful, which can potentially explain why people search using such an inefficient and distraction-prone strategy. However, this assumption remains largely untested. In the present study, we used a hand dynamometer to relate physical effort to perceived mental effort across different search conditions. Surprisingly, across three experiments, participants exerted more effort to avoid singleton detection trials compared to feature search trials, suggesting that they found singleton detection to be the more effortful mode of searching. In a fourth experiment, we removed the physical effort component and simply asked participants to self-report how effortful they perceived each search task to be. Participants robustly indicated that singleton detection trials were more effortful. Lastly, in a fifth experiment, we removed distractor-present trials. Again, participants exerted more effort to avoid singleton detection trials. In contrast to widely held assumptions, our findings suggest that searching for a salient singleton is in fact more mentally effortful than searching for a specific feature in a heterogeneous display, which has broad implications for theories of attentional control and the influence of mental effort on cognition. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Remapping time across space.

Multiple lines of evidence indicate that visual attention's temporal properties differ between the left and right visual fields (LVF and RVF). Notably, recent electroencephalograph recordings indicate that event-related potentials peak earlier for LVF than for RVF targets on bilateral-stream rapid serial visual presentation (RSVP) identification tasks. Might this hastened neural response render LVF targets perceptually available sooner than RVF targets? If so, how might the visual system reconcile these timing differences to estimate simultaneity across the LVF and RVF? We approached these questions by presenting bilateral-stream RSVP displays that contained opposite-hemifield targets and requiring participants to judge both the targets' temporal order and simultaneity. The temporal order judgments (TOJs) revealed that participants perceived LVF targets ∼134 ms sooner than RVF targets. This LVF hastening approximates a full cycle of visual attention's canonical ∼10 Hz (∼100 ms) temporal resolution. In contrast, performance on the simultaneity task did not exhibit the LVF hastening observed on the TOJ task, despite identical retinal stimulation across the two tasks. This finding rules out a stimulus-driven "bottom-up" explanation for the task-specific behavior. Moreover, error patterns across the two tasks revealed that, within the decision stage of simultaneity judgments, participants remapped LVF targets, but not RVF targets, to a later time in the RSVP sequence. Such hemifield-specific remapping would effectively compensate for the cross-hemifield asymmetries in neural response latencies that could otherwise impair simultaneity estimates.

Statistical learning facilitates the strategic use of attentional control.

A growing body of research suggests that observers rely on a variety of suboptimal strategies when searching for objects. However, real-world environments contain a variety of statistical regularities that enable more efficient processing of information. In the present study, we examined whether statistical learning can influence the strategic use of attentional control using a modified version of the adaptive choice visual search task. Participants searched through an array of colored squares and identified a digit located within a red or blue target square. Each trial contained both a red and a blue target, and participants were free to choose which color to search for. On each trial, more squares were presented in one color than the other color. Thus, the optimal strategy was to search for the color with the fewest squares. Critically, one color was the optimal color on 75% of trials, while the other color was the optimal color on the remaining 25% of trials. Participants were faster to identify targets and made a larger proportion of optimal choices when the high-probability optimal color was optimal. Thus, statistical learning facilitated both search for the targets and the optimal choice of attentional control settings. These effects persisted when the color contingencies were equated, suggesting that these findings were not simply due to intertrial priming. Moreover, participants were not slower to identify targets when the high-probability optimal color appeared as a distractor, suggesting that these findings were not due to attentional capture by this color. Together, these findings suggest that statistical learning can facilitate the strategic use of attentional control by biasing which features observers choose to search for.

Generalisation of value-based attentional priority is category-specific.

A large body of research suggests that previously reward-associated stimuli can capture attention. Recent evidence also suggests that value-driven attentional biases can occur for a particular category of objects. However, it is unclear how broadly these category-level attentional biases can generalise. In the present study, we examined whether value-driven attentional biases can generalise to new exemplars of a category or semantically related categories using a modified version of the value-driven attentional capture paradigm. In an initial training phase, participants searched for two categories of objects and were rewarded for correctly fixating members of one target category. In a subsequent test phase, participants searched for two new categories of objects. A new exemplar of one of the previous target categories or a member of a semantically related category could appear as a critical distractor in this phase. Participants were more likely to initially fixate the critical distractor and fixated the distractor longer when it was a new exemplar of the previously rewarded category. However, similar findings were not observed for members of semantically related categories. Together, these findings suggest that the generalisation of value-based attentional priority is category-specific.

Hepatocyte-derived DPP4 regulates portal GLP-1 bioactivity, modulates glucose production, and when absent influences NAFLD progression.

Elevated circulating dipeptidyl peptidase-4 (DPP4) is a biomarker for liver disease, but its involvement in gluconeogenesis and metabolic associated fatty liver disease progression remains unclear. Here, we identified that DPP4 in hepatocytes but not TEK receptor tyrosine kinase-positive endothelial cells regulates the local bioactivity of incretin hormones and gluconeogenesis. However, the complete absence of DPP4 (Dpp4-/-) in aged mice with metabolic syndrome accelerates liver fibrosis without altering dyslipidemia and steatosis. Analysis of transcripts from the livers of Dpp4-/- mice displayed enrichment for inflammasome, p53, and senescence programs compared with littermate controls. High-fat, high-cholesterol feeding decreased Dpp4 expression in F4/80+ cells, with only minor changes in immune signaling. Moreover, in a lean mouse model of severe nonalcoholic fatty liver disease, phosphatidylethanolamine N-methyltransferase mice, we observed a 4-fold increase in circulating DPP4, in contrast with previous findings connecting DPP4 release and obesity. Last, we evaluated DPP4 levels in patients with hepatitis C infection with dysglycemia (Homeostatic Model Assessment of Insulin Resistance > 2) who underwent direct antiviral treatment (with/without ribavirin). DPP4 protein levels decreased with viral clearance; DPP4 activity levels were reduced at long-term follow-up in ribavirin-treated patients; but metabolic factors did not improve. These data suggest elevations in DPP4 during hepatitis C infection are not primarily regulated by metabolic disturbances.

Adaptation to short-term extreme fat consumption alters intestinal lipid handling in male and female mice.

The small intestine is a highly adaptable organ serving as both a barrier to the external environment and a conduit for nutrient absorption. Enterocytes package dietary triglycerides (TG) into chylomicrons for transport into circulation; the remaining TGs are stored in cytosolic lipid droplets (CLDs). The current study aimed to characterize the impact of diet composition on intestinal lipid handling in male and female wild-type mice. Mice were continued on their grain-based diet (GBD) and switched to either a high-fat, high cholesterol Western-style diet (WD) or a ketogenic diet (KD) for 3 or 5 weeks. KD-fed mice displayed significantly higher plasma TG levels in response to an olive oil gavage than WD- and GBD-fed mice; TG levels were ~2-fold higher in male KD-fed mice than female KD-fed mice. Poloxamer-407 experiments revealed enhanced intestinal-TG secretion rates in male mice fed a KD upon olive oil gavage, whereas secretion rates were unchanged in female mice. Surprisingly, jejunal CLD size and TG mass after oil gavage were similar among the groups. At fasting, TG mass was significantly higher in the jejunum of male KD-fed mice and the duodenum of female KD-fed mice, providing increased substrate for chylomicron formation. In addition to greater fasting intestinal TG stores, KD-fed male mice displayed longer small intestinal lengths, while female mice displayed markedly longer jejunal villi lengths. After 5 weeks of diet, 12 h fasting-2 h refeeding experiments revealed jejunal TG levels were similar between diet groups in male mice; however, in female mice, jejunal TG mass was significantly higher in KD-fed mice compared to GBD- and WD-fed mice. These experiments reveal that KD feeding promotes distinct morphological and functional changes to the murine small intestine compared to the WD diet. Moreover, changes to intestinal lipid handling in response to carbohydrate and protein restriction manifest differently in male and female mice.

Typicality modulates attentional capture by object categories.

What we pay attention to in the visual environment is often driven by what we know about the world. For example, a number of studies have found that observers can adopt attentional sets for a particular semantic category. However, some objects are more typical members of a category than others. While previous evidence suggests that an object's typicality can influence the guidance of attention in visual search, it is unclear whether typicality can also influence the capture of attention. To test whether this is the case, participants were given a category of objects at the beginning of each trial. Then, a rapid serial visual presentation (RSVP) stream was presented at fixation, and participants had to indicate whether an object of the given category was present or absent from the stream. Importantly, a single flanker image also appeared above or below the central stream just before the target. This flanker could belong either to the same category as the target or a different category, and could be a typical or atypical exemplar of that category. Participants were less accurate at detecting the target when the flanker belonged to the same category as the target. Moreover, participants were even less accurate when the flanker was a typical exemplar of this category. Similar findings were observed when targets consisted of typical and atypical exemplars. Together, these findings indicate that the extent of attentional capture toward a distractor depends on whether the distractor matches the category and typicality of one's attentional set.

The past, present, and future of selection history.

The last ten years of attention research have witnessed a revolution, replacing a theoretical dichotomy (top-down vs. bottom-up control) with a trichotomy (biased by current goals, physical salience, and selection history). This third new mechanism of attentional control, selection history, is multifaceted. Some aspects of selection history must be learned over time whereas others reflect much more transient influences. A variety of different learning experiences can shape the attention system, including reward, aversive outcomes, past experience searching for a target, target‒non-target relations, and more. In this review, we provide an overview of the historical forces that led to the proposal of selection history as a distinct mechanism of attentional control. We then propose a formal definition of selection history, with concrete criteria, and identify different components of experience-driven attention that fit within this definition. The bulk of the review is devoted to exploring how these different components relate to one another. We conclude by proposing an integrative account of selection history centered on underlying themes that emerge from our review.

Updating perception and action across real-world viewpoint changes.

A growing body of research suggests that performing actions can distort the perception of size, distance, and other visual information. These distortions have been observed under a variety of circumstances, and appear to persist in both perception and memory. However, it is unclear whether these distortions persist as observers move to new viewpoints. To address this issue, the present study assessed whether action-specific distortions persist across changes in viewpoint. Participants viewed an object that was projected onto a table, then reached for it with their index finger or a reach-extending tool. After reaching for the object, participants remained stationary or moved to a new viewpoint, then estimated the object's distance from their current viewpoint. When participants remained stationary, using a reach-extending tool led them to report shorter distance estimates. However, when participants moved to a new viewpoint, these distortions were eliminated. Similar effects were observed when participants produced different types of movement, including when participants rotated in place, moved to a new location, or simply walked in place. Together, these findings suggest that action-specific distortions are eliminated when observers move and perform other actions.

Shifting attention does not influence numerical processing.

Many theories of numerical cognition assume that numbers and space share a common representation at the response level. For example, observers are faster to respond to small numbers with their left hand and large numbers with their right hand (the SNARC effect). There is also evidence that viewing numbers can produce spatial shifts of attention, suggesting that attention may play a role in the spatial representation of numbers. In the present study, we assessed whether shifts of attention can influence numerical processing. Participants viewed a leftward or rightward peripheral cue followed by a centrally presented number, then judged whether the number was odd or even. Participants responded faster and made fewer errors when the number magnitude and response side were compatible, revealing a response-based SNARC effect. Participants also responded faster when the cue direction and response side were compatible, revealing a Simon effect. However, participants did not respond faster when the cue direction and number magnitude were compatible. Similar findings were observed when the association between numbers and space was relatively explicit. Moreover, although we failed to observe a response-based SNARC effect when number magnitude was directly relevant to observers' task, we observed a large Simon effect. Together, these findings suggest that although numbers and space share a common representation at the response level, attention does not play a substantial role in the spatial representation of numbers.

The functional arrangement of objects biases gaze direction.

A growing number of studies suggest that semantic knowledge can influence the control of gaze in scenes. For example, observers are more likely to look toward objects that are semantically related to the currently fixated object. Recent evidence also suggests that an object's functional orientation can bias gaze direction. However, it is unknown whether these semantic and functional relationships can interact to determine gaze control. To address this issue, the present study assessed whether the functional arrangement of multiple objects can influence gaze control. Participants fixated a central object (e.g., a key) flanked by two peripheral objects. After a brief delay, participants were free to shift their gaze toward the peripheral object of their choice. One of the peripheral objects was semantically related to the central object (e.g., a lock), and the objects were arranged to depict a functional or non-functional interaction (e.g., a key pointing toward or away from a lock). When the orientation of the central object was manipulated, participants were more likely to look in the direction this object was pointing. Moreover, the functional arrangement of objects modulated this central orienting bias. However, when the orientation of the peripheral objects was manipulated, only the peripheral objects' semantic relationships influenced gaze control. Together, these findings suggest that functional relationships play an important role in the allocation of gaze, and can interact with semantic relationships to determine gaze control.

Semantic associations do not modulate the visual awareness of objects.

When observers adopt a category-level attentional set, objects that belong to the same category as this attentional set are more likely to enter awareness. For example, a driver who is monitoring the road for cars may be more likely to notice an oncoming car than a pedestrian who is crossing the road. Semantic associations between categories are also known to influence the deployment of attention, but it is unclear whether these associative relationships can influence the visual awareness of objects. To address this issue, we conducted four experiments using an inattentional blindness task. Participants tracked moving images of animals (e.g., monkeys or rabbits). On the last trial, an unexpected object that could belong to the same category as the tracked objects (i.e., a monkey or rabbit) or a semantically associated category (i.e., a banana or carrot) moved across the display. Participants were more likely to notice this object when it was visually salient or belonged to the same category as the tracked objects. However, they were no more likely to notice objects that shared a semantic association with the tracked objects. Thus, although categorical relationships play an important role in the visual awareness of objects, this effect does not extend to associative relationships among objects.

Satisfaction in motion: Subsequent search misses are more likely in moving search displays.

People often conduct visual searches in which multiple targets are possible (e.g., medical X-rays can contain multiple abnormalities). In this type of search, observers are more likely to miss a second target after having found a first one (a subsequent search miss). Recent evidence has suggested that this effect may be due to a depletion of cognitive resources from tracking the identities and locations of found targets. Given that tracking moving objects is resource-demanding, would finding a moving target further increase the chances of missing a subsequent one? To address this question, we had participants search for one or more targets hidden among distractors. Subsequent search misses were more likely when the targets and distractors moved throughout the display than when they remained stationary. However, when the found targets were highlighted in a unique color, subsequent search misses were no more likely in moving displays. Together, these results suggest that the effect of movement is likely due to the increased cognitive demands of tracking moving targets. Overall, our findings reveal that activities that involve searching for moving targets (e.g., driving) are more susceptible to subsequent search misses than are those that involve searching for stationary targets (e.g., baggage screening).

Semantic and functional relationships among objects increase the capacity of visual working memory.

Visual working memory (VWM) has a limited capacity of approximately 3-4 visual objects. Current theories of VWM propose that a limited pool of resources can be flexibly allocated to objects, allowing them to be represented at varying levels of precision. Factors that influence the allocation of these resources, such as the complexity and perceptual grouping of objects, can thus affect the capacity of VWM. We sought to identify whether semantic and functional relationships between objects could influence the grouping of objects, thereby increasing the functional capacity of VWM. Observers viewed arrays of 8 to-be-remembered objects arranged into 4 pairs. We manipulated both the semantic association and functional interaction between the objects, then probed participants' memory for the arrays. When objects were semantically related, participants' memory for the arrays improved. Participants' memory further improved when semantically related objects were positioned to interact with each other. However, when we increased the spacing between the objects in each pair, the benefits of functional but not semantic relatedness were eliminated. These findings suggest that action-relevant properties of objects can increase the functional capacity of VWM, but only when objects are positioned to directly interact with each other. (PsycINFO Database Record

Compression of environmental representations following interactions with objects.

Previous work reveals that interacting with all objects in an environment can compress spatial memory for the entire group of objects. To assess the scope and magnitude of this effect, we tested whether interacting with a subset of objects compresses spatial memory for all objects in an environment. Participants inspected objects in one or two unmarked regions of space, then recalled the distances between pairs of objects from memory. One group of participants picked up objects in both regions, a second group picked up objects in one region and passively viewed objects in the other region, and a third group passively viewed objects in both regions. When participants manually interacted with objects, they recalled shorter object-pair distances throughout the environment. The magnitude of this effect was the same, regardless of whether participants interacted with all objects in the environment or just a subset of them. Together, these findings suggest that interacting with objects can compress environmental representations in memory, even when observers interact with a relatively small subset of objects.

The whole is faster than its parts: evidence for temporally independent attention to distinct spatial locations.

Behavioral and electrophysiological evidence suggests that visual attention operates in parallel at distinct spatial locations and samples the environment in periodic episodes. This combination of spatial and temporal characteristics raises the question of whether attention samples locations in a phase-locked or temporally independent manner. If attentional sampling rates were phase locked, attention would be limited by a global sampling rate. However, if attentional sampling rates were temporally independent, they could operate additively to sample higher rates of information. We tested these predictions by requiring participants to identify targets in 2 or 4 rapid serial visual presentation (RSVP) streams, synchronized or asynchronized to manipulate the rate of new information globally (across streams). Identification accuracy exhibited little or no change when the global rate of new information doubled from 7.5 to 15 Hz (Experiment 1) or quadrupled to 30 Hz (Experiment 2). This relatively stable identification accuracy occurred even though participants reliably discriminated 7.5 Hz synchronous displays from displays globally asynchronized at 15 and 30 Hz (Metamer Control Experiment). Identification accuracy in the left visual field also significantly exceeded that in the right visual field. Overall, our results are consistent with temporally independent attention across distinct spatial locations and support previous reports of a right parietal "when" pathway specialized for temporal attention.

Subglottic stenosis and socio-economic deprivation: a 6-year review of the Scottish National Service for Paediatric Complex Airway Reconstruction.

OBJECTIVE: Subglottic stenosis is the third most common cause of stridor in children, and severe cases may need surgical reconstruction. Babies born to parents in high-deprivation areas are at increased risk of prematurity and low birth weight. This may require intensive care admission with prolonged intubation, hence, putting them at increased risk of subglottic stenosis. We aimed to review cases of subglottic stenosis requiring surgical intervention in the Scottish population and its association with socio-economic deprivation. METHODS: We collected retrospective data on all children who underwent open reconstructive surgery for subglottic stenosis between January 2005 and January 2011 at the Royal Hospital for Sick Children, Yorkhill, which provides the national complex airway reconstruction service for Scotland. The Scottish Index of Multiple Deprivation (SIMD) was used to categorise deprivation based on the child's home postal code. Incidence figures were calculated based on the total number of births in each deprivation category over the time period. RESULTS: There were a total of 53 cases of subglottic stenosis undergoing surgery in Scotland over the last 6 years, of which 31 were acquired and 22 were congenital. The most common procedure performed was laryngotracheal reconstruction with cartilage grafts (46 cases). No association was found between deprivation and the incidence of acquired or congenital subglottic stenosis. CONCLUSION: Our data is the first attempt to review the incidence of subglottic stenosis in the Scottish population and its association with deprivation. Perhaps surprisingly, we found no association.

An audit of prophylactic antibiotic use in laryngeal reconstruction surgery.

OBJECTIVE: Published data on the role of antibiotics after open airway reconstruction surgery in children is lacking. We reviewed adherence to our own departmental antibiotic protocol to determine its adequacy and effectiveness. METHODS: We reviewed the records of all children undergoing open airway reconstruction surgery 2003-2007 in our unit which is based in a tertiary referral children's hospital. RESULTS: 36 children underwent surgery, of whom 32 were given appropriate antibiotic prophylaxis. Failure to give antibiotic prophylaxis was associated with increased rates of infection (wound infection and pneumonia) and with a longer stay in the ITU. CONCLUSIONS: We present a revised antibiotic protocol based on our experience and local antibiotic advice.