6,873 research outputs found
Processing affective images in the absence of visual awareness
No full textGiven capacity limits, the visual system must prioritize the processing of sensory inputs that are most critical to successful interactions with the environment. Neurocognitive theories suggest that humans have evolved mechanisms that operate without awareness that selectively prioritize threatening stimuli in subsequent allocation of processing resources and access to awareness. Evidence for this ‘standard hypothesis’comes from paradigms that dissociate visual input from awareness. This thesis combines a narrative review, a meta-analytic review and three empirical studies to examine the extent to which emotionally salient stimuli are prioritized in the absence of awareness.A general introduction and review of the literature is provided in Chapter 1. The meta analysis of previous literature (Chapter 2) reveals that evidence for an unconscious processing bias for threat isundermined by insufficiently rigorous awareness measures and inadequate control of low-level confounds. Chapter 3 reveals that autonomic arousal and attentional orienting to visual threats are eliminated under conditions where observers are objectively unaware of stimuli. Chapter 4 reveals that prioritized processing of fearful faces is parsimoniously explained by effective contrast: the relationship betweentheir Fourier spectrum and the contrast sensitivity function. Importantly, this explanation does not require or involve unconscious processing mechanisms that are sensitive to threat. Chapter 5 reveals that prioritized processing of emotional face stimuli is restricted to conditions of awareness, and may be parsimoniously explained by simple low-level variability between emotional and neutral face stimuli.Previous and present findings and analyses are considered together in the discussion (Chapter 6). It is concluded that evidence for emotion-sensitive visual processing that operates without awareness is weak and that uncritical acceptance of the standard hypothesis is premature
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Fearful faces have a sensory advantage in the competition for awareness
No full textOnly a subset of visual signals give rise to a conscious percept. Threat signals, such as fearful faces, are particularly salient to human vision. Research suggests that fearful faces are evaluated without awareness and preferentially promoted to conscious perception. This agrees with evolutionary theories that posit a dedicated pathway specialized in processing threat-relevant signals. We propose an alternative explanation for this “fear advantage.” Using psychophysical data from continuous flash suppression (CFS) and masking experiments, we demonstrate that awareness of facial expressions is predicted by effective contrast: the relationship between their Fourier spectrum and the contrast sensitivity function. Fearful faces have higher effective contrast than neutral expressions and this, not threat content, predicts their enhanced access to awareness. Importantly, our findings do not support the existence of a specialized mechanism that promotes threatening stimuli to awareness. Rather, our data suggest that evolutionary or learned adaptations have molded the fearful expression to exploit our general-purpose sensory mechanisms
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Do emotional faces capture attention, and does this depend on awareness? Evidence from the visual probe paradigm
No full textThe visual probe (VP) paradigm provides evidence that emotional stimuli attract attention. Such effects have been reported even when stimuli are presented outside of awareness. These findings have shaped the idea that humans possess a processing pathway that detects evolutionarily significant signals independently of awareness. Here, we addressed 2 unresolved questions: First, if emotional stimuli attract attention, is this driven by their affective content, or by low-level image properties (e.g., luminance contrast)? Second, does attentional capture occur under conditions of genuine unawareness? We found that observers preferentially allocated attention to emotional faces under aware viewing conditions. However, this effect was best explained by low-level stimulus properties, rather than emotional content. When stimuli were presented outside of awareness (via continuous flash suppression or masking), we found no evidence that attention was directed toward emotional face stimuli. Finally, observer’s awareness of the stimuli (assessed by d′) predicted attentional cuing. Our data challenge existing literature: First, we cast doubt on the notion of preferential attention to emotional stimuli in the absence of awareness. Second, we question whether effects revealed by the VP paradigm genuinely reflect emotion-sensitive processes, instead suggesting they can be more parsimoniously explained by low-level variability between stimuli
Interview with Nicholas Christopher, author of Somewhere in the Night: Film Noir and the American City
No full textInterview with Nicholas Christopher, author of Somewhere in the Night: Film Noir and the American Cit
Resurrecting the Author
No full textPresentation of Nicholas Wolterstorff\u27s Paper Resurrecting the Author with time after for questions beginning at 18:00
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Are visual threats prioritized without awareness? A critical review and meta analysis involving 3 behavioral paradigms and 2696 observers
No full textGiven capacity limits, only a subset of stimuli give rise to a conscious percept. Neurocognitive models suggest that humans have evolved mechanisms that operate without awareness and prioritize threatening stimuli over neutral stimuli in subsequent perception. In this meta analysis, we review evidence for this ‘standard hypothesis’ emanating from three widely used, but rather different experimental paradigms that have been used to manipulate awareness. We found a small pooled threat-bias effect in the masked visual probe paradigm, a medium effect in the binocular rivalry paradigm and highly inconsistent effects in the breaking continuous flash suppression paradigm. Substantial heterogeneity was explained by the stimulus type: the only threat stimuli that were robustly prioritized across all three paradigms were fearful faces. Meta regression revealed that anxiety may modulate threat-biases, but only under specific presentation conditions. We also found that insufficiently rigorous awareness measures, inadequate control of response biases and low level confounds may undermine claims of genuine unconscious threat processing. Considering the data together, we suggest that uncritical acceptance of the standard hypothesis is premature: current behavioral evidence for threat-sensitive visual processing that operates without awareness is weak
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Motion adaptation and attention: a critical review and meta-analysis
No full textThe motion aftereffect (MAE) provides a behavioural probe into the mechanisms underlying motion perception, and has been used to study the effects of attention on motion processing. Visual attention can enhance detection and discrimination of selected visual signals. However, the relationship between attention and motion processing remains contentious: not all studies find that attention increases MAEs. Our meta-analysis reveals several factors that explain superficially discrepant findings.
Across studies (37 independent samples, 76 effects) motion adaptation was significantly and substantially enhanced by attention (Cohen’s d=1.12, p<.0001). The effect more than doubled when adapting to translating (vs. expanding or rotating) motion. Other factors affecting the attention-MAE relationship included stimulus size, eccentricity and speed. By considering these behavioural analyses alongside neurophysiological work, we conclude that feature-based (rather than spatial, or object-based) attention is the biggest driver of sensory adaptation.
Comparisons between naïve and non-naïve observers, different response paradigms, and assessment of ‘file-drawer effects’ indicate that neither response bias nor publication bias are likely to have significantly inflated the estimated effect of attention
Heritability and Linkage Analysis of Appendicitis Utilizing Age at Onset
No full textAppendicitis usually afflicts the young, but there is a large tail in the distribution of onset age. The genetics of this disease are still not well understood. A heritability analysis and genome wide linkage analysis of a large twin dataset was undertaken. Treating age of onset of appendicitis as a censored survival trait revealed a heritability of 0.21, and found evidence of linkage to Chromosome 1p37.3. Author(s): Christopher Oldmeadow 1 * | Kerrie Mengersen 2 | Nicholas Martin 3 | David L. Duffy
The precautionary demand for commodity stocks
No full textThis paper develops a theory of the precautionary demand for commodity stocks. It suggests that commodity stocks are held for precautionary purposes by producers, consumers, and intermediate processors, while speculators hold stocks on the expectation of capital gains from a subsequent price rise. Producer and consumer stocks usually account for the largest share of commercial stocks held at any point in time. For example, at the end of 1990, stocks held by producers and consumers of copper were 72 percent of all commercial stocks of the market economy countries. Yet, the theory explaining the behavior of this class of stocks has not progressed much beyond the concept of convenience yield, first introduced by Kaldor (1939). This paper proposes an alternative theory. Holding of stocks by producers and consumers is viewed as precautionary behavior towards output and price risks. As a theory of behavior towards risks, the precautionary stock demand model encompasses speculative demand by both producers and consumers. Furthermore, both stocks and futures are treated as precautionary instruments, in contrast to the dichotomy that only stocks provide convenience yield while futures are hedging instruments.Access to Markets,Markets and Market Access,Economic Theory&Research,Environmental Economics&Policies,Non Bank Financial Institutions
Nicholas de Monchaux: Local Code / Real Estates
No full textNicholas de Monchaux is an architect and urbanist whose work explores the intersections between nature, technology, and the city. He is the author of Spacesuit: Fashioning Apollo (MIT Press, 2011), an architectural history of the Apollo 11 spacesuit. He is Assistant Professor of Architecture and Urban Design at UC Berkeley. The work of his design studio has been exhibited widely and is currently being featured in the US Pavillion of the 13th Venice Biennale
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