Despite the massive capacity of visual long-term memory, individuals do not successfully encode all visual information they wish to remember. This variability in encoding success has been ...traditionally ascribed to fluctuations in individuals’ cognitive states (e.g., sustained attention) and differences in memory encoding processes (e.g., depth of encoding). However, recent work has shown that a considerable amount of variability in encoding success stems from intrinsic stimulus properties that determine the ease of encoding across individuals. While researchers have identified several perceptual and semantic properties that contribute to stimulus memorability, much remains unknown, including whether individuals are aware of the memorability of stimuli they encounter. In the present study, we investigated whether individuals have conscious access to the memorability of real-world stimuli while forming self-referential judgments of learning (JOL) during explicit memory encoding (Experiments
1
A–B) and when asked about the perceived memorability of a stimulus in the absence of attempted encoding (Experiments
2
A–B). We found that JOLs and perceived memorability estimates (PME) were consistent across individuals and predictive of memorability, confirming that individuals can access memorability with or without stimulus encoding. At the same time, access to memorability was not comprehensive. We found that individuals unexpectedly remembered and forgot consistent sets of stimuli as well. When we compared access to memorability between JOLs and PMEs, we found that individuals had more access during JOLs. Thus, our findings demonstrate that individuals have partial access to stimulus memorability and that explicit encoding increases the amount of access that is available.
Maintaining perceptual experiences in visual working memory (VWM) allows us to flexibly accomplish various tasks, but some tasks come at a price. For example, comparing VWM representations to novel ...perceptual inputs can induce inadvertent memory distortions. If these distortions can persist, they may explain why everyday memories often become unreliable after people perform perceptual comparisons (e.g., eyewitness testimony). Here, we conducted two experiments to assess the consequences of perceptual comparisons using real-world objects that were temporarily maintained in VWM (n = 32) or recalled from visual long-term memory back into VWM (n = 30). In each experiment, young adults reported systematic memory distortions following perceptual comparisons. These distortions increased in magnitude with the delay between encoding and comparisons and were preserved when memories were retrieved again a day later. These findings suggest that perceptual comparisons play a mechanistic role in everyday memory distortions, including situations where memory accuracy is vital.
Public Significance Statement
This study demonstrates that erroneous memory biases formed by comparing one's memory of a visual object to new objects in the surrounding environment may be permanent. In particular, memory biases reported immediately after comparing memories to new percepts were found to be nearly identical in magnitude when the same memories were recalled again 24 hr later, even when individuals expressed high confidence in the accuracy of both reports. The act of perceptual comparison may therefore provide a mechanistic explanation for perseverant errors described in eyewitness lineups where individuals confidently sustain false recognition judgments across time.
It is well-established that stimulus-specific information in visual working memory (VWM) can be systematically biased by new perceptual inputs. These memory biases are commonly attributed to ...interference that arises when perceptual inputs are physically similar to VWM contents. However, recent work has suggested that explicitly comparing the similarity between VWM contents and new perceptual inputs modulates the size of memory biases above and beyond stimulus-driven effects. Here, we sought to directly investigate this modulation hypothesis by comparing the size of memory biases following explicit comparisons to those induced when new perceptual inputs are ignored (Experiment
1
) or maintained in VWM alongside target information (Experiment
2
). We found that VWM reports showed larger attraction biases following explicit perceptual comparisons than when new perceptual inputs were ignored or maintained in VWM. An analysis of participants’ perceptual comparisons revealed that memory biases were amplified after perceptual inputs were endorsed as similar—but not dissimilar—to one’s VWM representation. These patterns were found to persist even after accounting for variability in the physical similarity between the target and perceptual stimuli across trials, as well as the baseline memory precision between the distinct task demands. Together, these findings illustrate a causal role of perceptual comparisons in modulating naturally-occurring memory biases.
Some stimuli are more memorable than others. Humans have demonstrated partial access to the properties that make a given stimulus more or less memorable. Recently, a deep neural network named ResMem ...was shown to successfully decode the memorability of visual stimuli as well. However, it remains unknown whether ResMem's predictions of memorability reflect the influence of stimulus-intrinsic properties or other stimulus-extrinsic factors that are known to induce interindividual consistency in memory performance (e.g., interstimulus similarity). Additionally, it is not clear whether ResMem and humans share access to overlapping properties of memorability. Here, in three experiments, we show that ResMem predicts stimulus-intrinsic memorability independent of stimulus-extrinsic factors, and that it captures aspects of memorability that are inaccessible to human observers. Taken together, our results confirm the multifaceted nature of memorability and establish a method for isolating its aspects that are largely inaccessible to humans.
Public Significance Statement
Some images are easier to remember than others, making some images more memorable than others consistently across human observers. Previous research has shown that both humans and a pretrained neural network called ResMem can predict image memorability. However, whether humans and ResMem rely on the same aspects of the images in predicting their memorability remains unclear. Our study first demonstrated that ResMem predicted the memorability of images without relying on their interitem similarity among other images. More crucially, we found that humans and ResMem used largely nonoverlapping aspects of images for memorability prediction, suggesting that ResMem can be used to elucidate the aspects of memorability that are not explicitly accessible to humans.
Comparing a visual memory with new visual stimuli can bias memory content, especially when the new stimuli are perceived as similar. Perceptual comparisons of this kind may play a mechanistic role in ...memory updating and can explain how memories can become erroneous in daily life. To test this possibility, we investigated whether comparisons can produce other types of memory distortion beyond memory bias that are commonly implicated in erroneous memories (e.g., memory misattribution). We hypothesized that the type of memory distortion induced during a comparison depends on the perceived overlap between the memory and incoming stimulus-when the input is perceived as similar, it biases memory content; when perceived as the same, it replaces memory content. Participants completed a delayed estimation task in which they compared their memories of color (Experiment 1) and shape stimuli (Experiment 2) to probe stimuli before reporting memory content. We found systematic errors in participants' memory reports following perceived similarity and sameness that were toward the probes and larger following perceived sameness. Simulations confirmed that these errors were not explained by noisy encoding processes that occurred before comparisons. Instead, computational modeling suggested that these errors were likely explained by the probabilistic replacement of the memory by the probe following perceived sameness and integration between the memory and the probe following perceived similarity. Together, these findings suggest that perceptual comparisons can prompt distinct forms of memory updating that have been described previously and may explain how memories become erroneous during their use in everyday behavior.
Public Significance StatementThis study demonstrates that explicitly comparing one's memory of a visual object to a new object that is currently perceived risks distorting the memory representation. In particular, these findings show that if the observer judges the remembered object and new object to be similar to one another, the remembered object becomes more alike than the new object, and if they are judged to be identical, the new object replaces the remembered object in memory. Perceptual comparisons may therefore provide a mechanistic explanation for the formation of false memories in everyday life, including critical scenarios, such as eyewitness lineups.
Visual information around us is rarely static. To perform a task in such a dynamic environment, we often have to compare current visual input with our working memory (WM) representation of the ...immediate past. However, little is known about what happens to a WM representation when it is compared with perceptual input. To test this, we asked young adults (N = 170 total in three experiments) to compare a new visual input with a WM representation prior to reporting the WM representation. We found that the perceptual comparison biased the WM report, especially when the input was subjectively similar to the WM representation. Furthermore, using computational modeling and individual-differences analyses, we found that this similarity-induced memory bias was driven by representational integration, rather than incidental confusion, between the WM representation and subjectively similar input. Together, our findings highlight a novel source of WM distortion and suggest a general mechanism that determines how WM interacts with new visual input.
Cognitive aging researchers have long reported "paradoxical" age differences in prospective memory (PM), with age deficits in laboratory settings and age benefits (or no deficits) in real-world ...settings. We propose a theoretical account that explains this "age-PM-paradox" as a consequence of both methodological factors and developmental changes in cognitive abilities and personality traits. To test this account, young and older adults performed a series of naturalistic PM tasks in the lab and real world. Age-related PM deficits were observed in both lab-based tasks where demands were implemented using virtual reality and in-person role-playing. In contrast, older adults performed equal to or better than young adults on both real-world tasks, where demands were implemented in participants' daily lives. Consistent with our proposed account, an index of these "paradoxical" effects was partially predicted by age-related differences in working memory, vigilance, agreeableness, and neuroticism, whose predictive utility varied across task settings.
Placement of an interatrial shunt device reduces pulmonary capillary wedge pressure during exercise in patients with heart failure and preserved or mildly reduced ejection fraction. We aimed to ...investigate whether an interatrial shunt can reduce heart failure events or improve health status in these patients.
In this randomised, international, blinded, sham-controlled trial performed at 89 health-care centres, we included patients (aged ≥40 years) with symptomatic heart failure, an ejection fraction of at least 40%, and pulmonary capillary wedge pressure during exercise of at least 25 mm Hg while exceeding right atrial pressure by at least 5 mm Hg. Patients were randomly assigned (1:1) to receive either a shunt device or sham procedure. Patients and outcome assessors were masked to randomisation. The primary endpoint was a hierarchical composite of cardiovascular death or non-fatal ischemic stroke at 12 months, rate of total heart failure events up to 24 months, and change in Kansas City Cardiomyopathy Questionnaire overall summary score at 12 months. Pre-specified subgroup analyses were conducted for the heart failure event endpoint. Analysis of the primary endpoint, all other efficacy endpoints, and safety endpoints was conducted in the modified intention-to-treat population, defined as all patients randomly allocated to receive treatment, excluding those found to be ineligible after randomisation and therefore not treated. This study is registered with ClinicalTrials.gov, NCT03088033.
Between May 25, 2017, and July 24, 2020, 1072 participants were enrolled, of whom 626 were randomly assigned to either the atrial shunt device (n=314) or sham procedure (n=312). There were no differences between groups in the primary composite endpoint (win ratio 1·0 95% CI 0·8–1·2; p=0·85) or in the individual components of the primary endpoint. The prespecified subgroups demonstrating a differential effect of atrial shunt device treatment on heart failure events were pulmonary artery systolic pressure at 20W of exercise (pinteraction=0·002 >70 mm Hg associated with worse outcomes), right atrial volume index (pinteraction=0·012 ≥29·7 mL/m2, worse outcomes), and sex (pinteraction=0·02 men, worse outcomes). There were no differences in the composite safety endpoint between the two groups (n=116 38% for shunt device vs n=97 31% for sham procedure; p=0·11).
Placement of an atrial shunt device did not reduce the total rate of heart failure events or improve health status in the overall population of patients with heart failure and ejection fraction of greater than or equal to 40%.
Corvia Medical.
There has been a substantial amount of research involving computer methods and technology for the detection and recognition of diabetic foot ulcers (DFUs), but there is a lack of systematic ...comparisons of state-of-the-art deep learning object detection frameworks applied to this problem. DFUC2020 provided participants with a comprehensive dataset consisting of 2,000 images for training and 2,000 images for testing. This paper summarizes the results of DFUC2020 by comparing the deep learning-based algorithms proposed by the winning teams: Faster R–CNN, three variants of Faster R–CNN and an ensemble method; YOLOv3; YOLOv5; EfficientDet; and a new Cascade Attention Network. For each deep learning method, we provide a detailed description of model architecture, parameter settings for training and additional stages including pre-processing, data augmentation and post-processing. We provide a comprehensive evaluation for each method. All the methods required a data augmentation stage to increase the number of images available for training and a post-processing stage to remove false positives. The best performance was obtained from Deformable Convolution, a variant of Faster R–CNN, with a mean average precision (mAP) of 0.6940 and an F1-Score of 0.7434. Finally, we demonstrate that the ensemble method based on different deep learning methods can enhance the F1-Score but not the mAP.
•We evaluate popular deep learning methods on diabetic foot ulcer (DFU) detection.•A new Cascade Attention Network (CA-DetNet) is proposed for DFU detection.•Ensemble methods are proposed and evaluated for DFU detection.•Faster R–CNN with deformable convolution achieved the best mAP on the DFUC2020 dataset.•Ensemble method achieved the best F1-Score in DFU detection on the DFUC2020 dataset.
Productive uses of lignin, the third most abundant natural polymer, have been sought for decades. One especially attractive possibility is that of developing value-added products including ...thermoplastics based on lignin. This possibility warrants special attention due to growth of the modern biofuel industries. However, the polydisperse molecular weight and hyper-branched structure of lignin has hindered the creation of high-performance biopolymers. Here, we report the preparation and characterization of novel lignin-based, partially carbon-neutral thermoplastics. We first altered the molecular weight of lignin, either by fractionation with methanol, or by formaldehyde crosslinking. Crosslinking of lignin increases the molecular weight, exhibiting M sub(n) = 31 000 g mol super(-1), whereas that of as-received lignin is 1840 g mol super(-1). Tuning the molecular weight of lignin enabled successful preparation of novel lignin-derived thermoplastics, when coupled with telechelic polybutadiene soft-segments at proper feed ratios. Characteristic to thermoplastic rubbers, free-standing films of the resulting copolymers exhibit two-phase morphology and associated relaxations in the dynamic mechanical loss spectrum. To the best of our knowledge this article is the first report to demonstrate phase immiscibility, melt-processibility, and biphasic morphology of soft and hard segments in a lignin-based copolymer for all feed ratios of two macromolecular components. The use of higher molecular weight lignin enhanced the resulting shear modulus due to efficient network formation of telechelic polybutadiene bridges. The storage modulus in the rubbery plateau region increased with increasing lignin content. The successful synthesis of novel lignin-based thermoplastics will open a new pathway to biomass utilization and will help conserve petrochemicals.
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