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Concept: Unsolved problems in neuroscience


Human perception is invariably accompanied by a graded feeling of confidence that guides metacognitive awareness and decision-making. It is often assumed that this arises solely from the feed-forward encoding of the strength or precision of sensory inputs. In contrast, interoceptive inference models suggest that confidence reflects a weighted integration of sensory precision and expectations about internal states, such as arousal. Here we test this hypothesis using a novel psychophysical paradigm, in which unseen disgust-cues induced unexpected, unconscious arousal just before participants discriminated motion signals of variable precision. Across measures of perceptual bias, uncertainty, and physiological arousal we found that arousing disgust cues modulated the encoding of sensory noise. Furthermore, the degree to which trial-by-trial pupil fluctuations encoded this nonlinear interaction correlated with trial level confidence. Our results suggest that unexpected arousal regulates perceptual precision, such that subjective confidence reflects the integration of both external sensory and internal, embodied states.

Concepts: Understanding, Cognition, Perception, Sense, Mind, Unsolved problems in neuroscience, Philosophy of perception, Sexual arousal


Point-of-care ultrasonography (POCUS) is a widely used tool in emergency and critical care settings, useful in the decision-making process as well as in interventional guidance. While having an impressive diagnostic accuracy in the hands of highly skilled operators, inexperienced practitioners must be aware of some common misinterpretations that may lead to wrong decisions at the bedside.

Concepts: Decision making, Critical thinking, Risk, Cognition, Decision theory, Philosophy of science, Unsolved problems in neuroscience, Acoustics


Consistency, quality, and duration of sleep are important determinants of health. We describe sleep patterns among demographically defined subgroups from the Youth Risk Behavior Surveillance System reported in 4 successive biennial representative samples of American high school students (2007 to 2013). Across the 4 waves of data collection, 6.2% to 7.7% of females and 8.0% to 9.4% of males reported obtaining 9 or more hours of sleep. Insufficient duration of sleep is pervasive among American high school students. Despite substantive public health implications, intervention research on this topic has received little attention.

Concepts: Public health, Epidemiology, Human, Sleep, Neuroscience, Unsolved problems in neuroscience, High school, Population health


To determine the relationship between sleep quality and CSF markers of Alzheimer disease (AD) pathology in late midlife.

Concepts: Alzheimer's disease, Memory, Unsolved problems in neuroscience, Beta amyloid


Numerous studies have shown that diagnostic failure depends upon a variety of factors. Psychological factors are fundamental in influencing the cognitive performance of the decision maker. In this first of two papers, we discuss the basics of reasoning and the Dual Process Theory (DPT) of decision making. The general properties of the DPT model, as it applies to diagnostic reasoning, are reviewed. A variety of cognitive and affective biases are known to compromise the decision-making process. They mostly appear to originate in the fast intuitive processes of Type 1 that dominate (or drive) decision making. Type 1 processes work well most of the time but they may open the door for biases. Removing or at least mitigating these biases would appear to be an important goal. We will also review the origins of biases. The consensus is that there are two major sources: innate, hard-wired biases that developed in our evolutionary past, and acquired biases established in the course of development and within our working environments. Both are associated with abbreviated decision making in the form of heuristics. Other work suggests that ambient and contextual factors may create high risk situations that dispose decision makers to particular biases. Fatigue, sleep deprivation and cognitive overload appear to be important determinants. The theoretical basis of several approaches towards debiasing is then discussed. All share a common feature that involves a deliberate decoupling from Type 1 intuitive processing and moving to Type 2 analytical processing so that eventually unexamined intuitive judgments can be submitted to verification. This decoupling step appears to be the critical feature of cognitive and affective debiasing.

Concepts: Decision making, Critical thinking, Risk, Cognition, Decision theory, Decision making software, Unsolved problems in neuroscience, Decision engineering


The pupil is primarily regulated by prevailing light levels but is also modulated by perceptual and attentional factors. We measured pupil-size in typical adult humans viewing a bistable-rotating cylinder, constructed so the luminance of the front surface changes with perceived direction of rotation. In some participants, pupil diameter oscillated in phase with the ambiguous perception, more dilated when the black surface was in front. Importantly, the magnitude of oscillation predicts autistic traits of participants, assessed by the Autism-Spectrum Quotient AQ. Further experiments suggest that these results are driven by differences in perceptual styles: high AQ participants focus on the front surface of the rotating cylinder, while those with low AQ distribute attention to both surfaces in a more global, holistic style. This is the first evidence that pupillometry reliably tracks inter-individual differences in perceptual styles; it does so quickly and objectively, without interfering with spontaneous perceptual strategies.

Concepts: Psychology, Perception, Sense, Mind, Unsolved problems in neuroscience, Philosophy of perception, Adult, Gestalt psychology


Insufficient sleep is a global public health problem resulting in catastrophic accidents, increased mortality, and hundreds of billions of dollars in lost productivity. Yet the effect of sleep deprivation (SD) on decision making and performance is often underestimated by fatigued individuals and is only beginning to be understood by scientists. The deleterious impact of SD is frequently attributed to lapses in vigilant attention, but this account fails to explain many SD-related problems, such as loss of situational awareness and perseveration. Using a laboratory study protocol, we show that SD individuals can maintain information in the focus of attention and anticipate likely correct responses, but their use of such a top-down attentional strategy is less effective at preventing errors caused by competing responses. Moreover, when the task environment requires flexibility, performance under SD suffers dramatically. The impairment in flexible shifting of attentional control we observed is distinct from lapses in vigilant attention, as corroborated by the specificity of the influence of a genetic biomarker, the dopaminergic polymorphism DRD2 C957T. Reduced effectiveness of top-down attentional control under SD, especially when conditions require flexibility, helps to explain maladaptive performance that is not readily explained by lapses in vigilant attention.

Concepts: Scientific method, Understanding, Attention, Effectiveness, Sleep deprivation, Cognition, Unsolved problems in neuroscience, Explanation


In people’s imagination, dying seems dreadful; however, these perceptions may not reflect reality. In two studies, we compared the affective experience of people facing imminent death with that of people imagining imminent death. Study 1 revealed that blog posts of near-death patients with cancer and amyotrophic lateral sclerosis were more positive and less negative than the simulated blog posts of nonpatients-and also that the patients' blog posts became more positive as death neared. Study 2 revealed that the last words of death-row inmates were more positive and less negative than the simulated last words of noninmates-and also that these last words were less negative than poetry written by death-row inmates. Together, these results suggest that the experience of dying-even because of terminal illness or execution-may be more pleasant than one imagines.

Concepts: Death, Senescence, Medical terms, Amyotrophic lateral sclerosis, Mind, Consciousness, Unsolved problems in neuroscience, Afterlife


We have previously found that attention to internal somatic sensations (interoceptive attention) during a heart beat perception task increases the misperception of external touch on a somatic signal detection task (SSDT), during which healthy participants erroneously report feeling near-threshold vibrations presented to their fingertip in the absence of a stimulus. However, it has been suggested that mindful interoceptive attention should result in more accurate somatic perception, due to its non-evaluative and controlled nature. To investigate this possibility, 62 participants completed the SSDT before and after a period of brief body-scan mindfulness meditation training, or a control intervention (listening to a recorded story). The meditation intervention reduced tactile misperception and increased sensitivity during the SSDT. This finding suggests that the perceptual effects of interoceptive attention depend on its particular nature, and raises the possibility that body-scan meditation could reduce the misperception of physical symptoms in individuals with medically unexplained symptoms.

Concepts: Cognition, Sense, Somatosensory system, Mind, Unsolved problems in neuroscience, Meditation, Mindfulness, Buddhist meditation


Researchers' understanding of bystanders' perspectives in the cyber-environment fails to take young people’s perceptions into account and remains imperfect. Interventions encouraging adolescents to help targets of cyber-aggression are therefore typically based upon traditional school-based aggression research. Twenty-four in-depth interviews with Australian 13-16 year-olds revealed two themes that reflect how young bystanders perceive differences between aggression online and at school. The physical presence theme suggests that young bystanders struggle to determine online intentions in the absence of body language, leading to hesitancy in reactions and furthermore make it easier for them to ignore online transgressions and avoid becoming involved. The authority theme indicates young bystanders perceive that, compared to the school environment, the online environment lacks clearly established rules, authority figures and formal reporting mechanisms. These differences indicate that unique strategies should be developed to encourage young bystanders to intervene in cyber-aggression situations.

Concepts: Psychology, Understanding, Perception, Sense, Mind, Unsolved problems in neuroscience, Youth, Theme