scholarly journals Faces under continuous flash suppression capture attention faster than objects, but without a face evoked steady-state visual potential: Is curvilinearity responsible for the behavioral effect?

2019 ◽  
Author(s):  
Andrew D. Engell ◽  
Henry Quillian
Keyword(s):  
Steady State ◽  
Face Perception ◽  
Behavioral Effect ◽  
Category Membership ◽  
List Type ◽  
Breakthrough Time ◽  
Interocular Suppression ◽  
Continuous Flash Suppression ◽  
Fearful Faces ◽  
Efficient Detection

AbstractFace perception is a vital part of human social interactions. The social value of faces makes their efficient detection evolutionarily advantageous. It has been suggested that this might occur nonconsciously, but experimental results are equivocal thus far. Here, we probe nonconscious face perception using a novel combination of binocular rivalry with continuous flash suppression, and steady-state visually evoked potentials. In the first two experiments, participants viewed either non-face objects, neutral faces (Study 1), or fearful faces (Study 2). Consistent with the hypothesis that faces are processed nonconsciously, we found that faces broke through suppression faster than objects. We did not, however, observe a concomitant face-selective SSVEP. Study 3 was run to reconcile this paradox. We hypothesized that the faster breakthrough time was due to a mid-level visual feature, curvilinearity, rather than high-level category membership, which would explain the behavioral difference without neural evidence of face-selective processing. We tested this hypothesis by presenting participants with four different groups of stimuli outside of conscious awareness: rectilinear objects (e.g., chessboard), curvilinear objects (e.g., dartboard), faces, and objects that were not dominantly curvilinear or rectilinear. We found that faces and curvilinear objects broke through suppression faster than objects and rectilinear objects. Moreover, there was no difference between faces and curvilinear objects. These results support our hypothesis that the observed behavioral advantage for faces is due to their curvilinearity, rather than category membership.HighlightsFaces presented outside of awareness do not evoke a steady-state visually evoked potential.This is true for both neutral and fearful faces.However, faces do breakthrough interocular suppression faster than objects.Curvilinear objects breakthrough interocular suppression faster than rectilinear objects.The breakthrough time advantage for faces over objects is due to their curvilinearity.

scholarly journals Color Can Shorten Breakthrough Times in Continuous Flash Suppression through Increased Salience and Task Relevance

Vision ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 13
Author(s):  
Christian Valuch
Keyword(s):  
Visual Search ◽  
Response Times ◽  
Top Down ◽  
Interocular Suppression ◽  
Continuous Flash Suppression ◽  
Task Relevance ◽  
Mediated Effects ◽  
Dominant Eye ◽  
Human Participants ◽  
And Task

Color can enhance the perception of relevant stimuli by increasing their salience and guiding visual search towards stimuli that match a task-relevant color. Using Continuous Flash Suppression (CFS), the current study investigated whether color facilitates the discrimination of targets that are difficult to perceive due to interocular suppression. Gabor patterns of two or four cycles per degree (cpd) were shown as targets to the non-dominant eye of human participants. CFS masks were presented at a rate of 10 Hz to the dominant eye, and participants had the task to report the target’s orientation as soon as they could discriminate it. The 2-cpd targets were robustly suppressed and resulted in much longer response times compared to 4-cpd targets. Moreover, only for 2-cpd targets, two color-related effects were evident. First, in trials where targets and CFS masks had different colors, targets were reported faster than in trials where targets and CFS masks had the same color. Second, targets with a known color, either cyan or yellow, were reported earlier than targets whose color was randomly cyan or yellow. The results suggest that the targets’ entry to consciousness may have been speeded by color-mediated effects relating to increased (bottom-up) salience and (top-down) task relevance.

scholarly journals Conscious perception of flickering stimuli in binocular rivalry and continuous flash suppression is not affected by tACS-induced SSR modulation

2019 ◽  
Author(s):  
Georg Schauer ◽  
Carolina Yuri Ogawa ◽  
Naotsugu Tsuchiya ◽  
Andreas Bartels
Keyword(s):  
Steady State ◽  
Binocular Rivalry ◽  
Occipital Cortex ◽  
Detection Accuracy ◽  
Conscious Perception ◽  
Continuous Flash Suppression ◽  
Transcranial Alternating Current Stimulation ◽  
Steady State Responses ◽  
State Responses ◽  
Flicker Stimulus

AbstractThe content of conscious perception is known to correlate with steady-state responses (SSRs), yet their causal relationship remains unclear. Can we manipulate conscious perception by directly interfering with SSRs through transcranial alternating current stimulation (tACS)? Here, we directly addressed this question in three experiments involving binocular rivalry and continuous flash suppression (CFS). Specifically, while participants (N=24) viewed either binocular rivalry or tried to detect stimuli masked by CFS, we applied sham or real tACS across parieto-occipital cortex at either the same or a different frequency and phase as an SSR eliciting flicker stimulus. We found that tACS did not differentially affect conscious perception in the forms of predominance, CFS detection accuracy, reaction time, or metacognitive sensitivity, confirmed by Bayesian statistics. We conclude that tACS application at frequencies of stimulus-induced SSRs does not have perceptual effects and that SSRs may be epiphenomenal to conscious perception.

scholarly journals Dimensions of Perception: 3D Real-Life Objects Are More Readily Detected Than Their 2D Images

2021 ◽  
pp. 095679762110107
Author(s):  
Uri Korisky ◽  
Liad Mudrik
Keyword(s):  
Young Adults ◽  
Augmented Reality ◽  
3D Printing ◽  
Real Life ◽  
Interocular Suppression ◽  
Continuous Flash Suppression ◽  
3D Objects ◽  
Real Objects ◽  
2D Images

Most of our interactions with our environment involve manipulating real 3D objects. Accordingly, 3D objects seem to enjoy preferential processing compared with 2D images, for example, in capturing attention or being better remembered. But are they also more readily perceived? Thus far, the possibility of preferred detection for real 3D objects could not be empirically tested because suppression from awareness has been applied only to on-screen stimuli. Here, using a variant of continuous flash suppression (CFS) with augmented-reality goggles (“real-life” CFS), we managed to suppress both real 3D objects and their 2D representations. In 20 healthy young adults, real objects broke suppression faster than their photographs. Using 3D printing, we also showed in 50 healthy young adults that this finding held only for meaningful objects, whereas no difference was found for meaningless, novel ones (a similar trend was observed in another experiment with 20 subjects, yet it did not reach significance). This suggests that the effect might be mediated by affordances facilitating detection of 3D objects under interocular suppression.

scholarly journals Holistic face processing is influenced by non-conscious visual information

2021 ◽  
Author(s):  
Haiyang Jin ◽  
Matt Oxner ◽  
Paul Michael Corballis ◽  
William Hayward
Keyword(s):  
Face Perception ◽  
Face Processing ◽  
Visual Information ◽  
Irrelevant Information ◽  
Composite Effect ◽  
Continuous Flash Suppression ◽  
Facial Information ◽  
Holistic Face Processing ◽  
Composite Face ◽  
Face Task

Holistic face processing has been widely implicated in conscious face perception. Yet, little is known about whether holistic face processing occurs when faces are processed unconsciously. The present study used the composite face task and continuous flash suppression (CFS) to inspect whether the processing of target facial information (the top half of a face) is influenced by irrelevant information (the bottom half) that is presented unconsciously. Results of multiple experiments showed that the composite effect was observed in both the monocular and CFS conditions, providing the first evidence that the processing of top facial halves is influenced by the aligned bottom halves no matter whether they are presented consciously or unconsciously. However, much of the composite effect for faces without masking was disrupted when bottom facial parts were rendered with CFS. These results suggest that holistic face processing can occur unconsciously, but also highlight the significance of holistic processing of consciously presented faces.

scholarly journals fluxweb: a R package to easily estimate energy fluxes in food webs

2017 ◽  
Author(s):  
Benoit Gauzens ◽  
Andrew Barnes ◽  
Darren Giling ◽  
Jes Hines ◽  
Malte Jochum ◽  
...  
Keyword(s):  
Steady State ◽  
Food Web ◽  
Food Webs ◽  
Ecosystem Functioning ◽  
R Package ◽  
Estimation Methods ◽  
List Type ◽  
Energy Fluxes ◽  
Flux System ◽  
Primary Output

AbstractUnderstanding how changes in biodiversity will impact the stability and functioning of ecosystems is a central challenge in ecology. Food-web approaches have been advocated to link community composition with ecosystem functioning by describing the fluxes of energy among species or trophic groups. However, estimating such fluxes remains problematic because current methods become unmanageable as network complexity increases.We developed a generalisation of previous indirect estimation methods assuming a steady state system [1, 2, 3]: the model estimates energy fluxes in a top-down manner assuming system equilibrium; each node’s losses (consumption and physiological) balances its consumptive gains. Jointly, we provide theoretical and practical guidelines to use the fluxweb R package (available on CRAN at https://bit.ly/2OC0uKF).We also present how the framework can merge with the allometric theory of ecology [4] to calculate fluxes based on easily obtainable organism-level data (i.e. body masses and species groups -eg, plants animals), opening its use to food webs of all complexities. Physiological losses (metabolic losses or losses due to death other than from predation within the food web) may be directly measured or estimated using allometric relationships based on the metabolic theory of ecology, and losses and gains due to predation are a function of ecological efficiencies that describe the proportion of energy that is used for biomass production.The primary output is a matrix of fluxes among the nodes of the food web. These fluxes can be used to describe the role of a species, a function of interest (e.g. predation; total fluxes to predators), multiple functions, or total energy flux (system throughflow or multitrophic functioning). Additionally, the package includes functions to calculate network stability based on the Jacobian matrix, providing insight into how resilient the network is to small perturbations at steady state.Overall, fluxweb provides a flexible set of functions that greatly increase the feasibility of implementing food-web energetic approaches to more complex systems. As such, the package facilitates novel opportunities for mechanistically linking quantitative food webs and ecosystem functioning in real and dynamic natural landscapes.

scholarly journals Rapid neural categorization of facelike objects predicts the perceptual awareness of a face (face pareidolia)

2021 ◽  
Author(s):  
Diane Rekow ◽  
Jean-Yves Baudouin ◽  
Renaud Brochard ◽  
Bruno Rossion ◽  
Arnaud Leleu
Keyword(s):  
Face Perception ◽  
Subjective Experience ◽  
Brain Activity ◽  
List Type ◽  
Perceptual Awareness ◽  
Face Categorization ◽  
Illusory Perception ◽  
Neural Signature ◽  
Scalp Electroencephalogram ◽  
Human Faces

AbstractThe human brain rapidly and automatically categorizes faces vs. other visual objects. However, whether face-selective neural activity predicts the subjective experience of a face – perceptual awareness – is debated. To clarify this issue, here we use face pareidolia, i.e., the illusory perception of a face, as a proxy to relate the neural categorization of a variety of facelike objects to conscious face perception. In Experiment 1, scalp electroencephalogram (EEG) is recorded while pictures of human faces or facelike objects – in different stimulation sequences – are interleaved every second (i.e., at 1 Hz) in a rapid 6-Hz train of natural images of nonface objects. Participants do not perform any explicit face categorization task during stimulation, and report whether they perceived illusory faces post-stimulation. A robust categorization response to facelike objects is identified at 1 Hz and harmonics in the EEG frequency spectrum with a facelike occipito-temporal topography. Across all individuals, the facelike categorization response is of about 20% of the response to human faces, but more strongly right-lateralized. Critically, its amplitude is much larger in participants who report having perceived illusory faces. In Experiment 2, facelike or matched nonface objects from the same categories appear at 1 Hz in sequences of nonface objects presented at variable stimulation rates (60 Hz to 12 Hz) and participants explicitly report after each sequence whether they perceived illusory faces. The facelike categorization response already emerges at the shortest stimulus duration (i.e., 17 ms at 60 Hz) and predicts the behavioral report of conscious perception. Strikingly, neural facelike-selectivity emerges exclusively when participants report illusory faces. Collectively, these experiments characterize a neural signature of face pareidolia in the context of rapid categorization, supporting the view that face-selective brain activity reliably predicts the subjective experience of a face from a single glance at a variety of stimuli.Highlights- EEG frequency-tagging measures the rapid categorization of facelike objects- Facelike objects elicit a facelike neural categorization response- Neural face categorization predicts conscious face perception across variable inputs

scholarly journals P027 Teicoplanin: evaluation of serum concentrations

2019 ◽  
Vol 104 (7) ◽  
pp. e2.31-e2
Author(s):  
Ibrahim Vhora ◽  
Andrew Taylor
Keyword(s):  
Intensive Care ◽  
Steady State ◽  
Serum Concentration ◽  
Population Pharmacokinetics ◽  
List Type ◽  
Serum Concentrations ◽  
Product Characteristics ◽  
Target Concentration ◽  
Summary Of Product Characteristics ◽  
Clinical Records

AimThe trust has implemented the use of therapeutic drug monitoring (TDM) of teicoplanin on intensive care following research that identified great variability in population pharmacokinetics in children.1–3 The summary of the research available showed that patients are not achieving target concentrations. This retrospective audit aimed to evaluate whether patients were achieving target serum concentrations. It also evaluated whether teicoplanin TDM was correctly completed for each patient. The following objectives were set based on grey literature and the Summary of Product Characteristics:4 Evaluate if serum concentrations are being taken on or after day 4 post initiation (steady state), and within 1 hour pre-dose (trough) Assess if serum concentrations reach target concentration with standard initial BNFC dosing appropriate for the indication of treatment.MethodsA retrospective report of teicoplanin serum concentrations was provided by the biochemistry labs covering a 6 month period. This report was used to identify the patients for the audit. For each patient: dose information, times and clinical particulars were obtained via the electronic prescribing system, Meditech version 6. If needed, clinical records were obtained from the medical records archive.Results71 serum concentrations were identified. 11 were excluded due to unobtainable or incomplete data. Serum concentrations were then evaluated for accuracy. The criteria set for determining accuracy were: Serum concentration taken on or after day 4 post initiation (steady state) Serum concentration taken within 1 hour pre dose (trough) Patient prescribed correct BNFC dosing regimen 55% (n=33) of patients had all 3 criteria met for an accurate concentration to be determined. This meant 45% of our patients serum concentrations could not be used to accurately evaluate if current dosing regimens promptly achieve target concentrations. Using the patients’ serum concentrations that followed the above criteria, it was found that 64% of these patients did not reach their desired target concentration. This included patients with: endocarditis (n=5) – aiming for trough greater than 30 mg/L cystic fibrosis (n=1) – aiming for trough greater than 20 mg/L other infections such as sepsis (n=27) – aiming for trough greater than 15 mg/L No patient included in this audit that required a higher target concentration reached their target before the first serum concentration.ConclusionIt is evident that teicoplanin TDM, which is still in its infancy at the trust, requires further support to improve practice. From the serum concentrations that were carried out correctly, this audit begins to illustrate a number of issues surrounding teicoplanin dosing in paediatric patients, especially those with difficult to treat infections. Further research is required to assess how these correlate to clinical outcome in practice as well as evaluating patients not in an intensive care setting. This study can be a driving force for a larger scale study to be carried out so that recommendations can be established and a change of practice can be implemented.ReferencesRamos-Martín V, Paulus S, Siner S, et al. Population Pharmacokinetics of Teicoplanin in Children. J Antimicrob. Chemother 2014;58: 6920–6927Harding I, Macgowan AP, White LO, et al. Teicoplanin therapy for Staphylococcus aureus septicaemia: relationship between pre-dose serum concentrations and outcome. J. Antimicrob. Chemother 2000;45:835–841.Reed MD, Yamashita TS, Myers CM, et al. The pharmacokinetics of teicoplanin in infants and children. J. Antimicrob. Chemother 1997;39:789–796.Targocid 400mg [Internet]. Targocid 400mg - Summary of Product Characteristics (SmPC) - (eMC). Available from: https://www.medicines.org.uk/emc/product/2927 (Accessed 20 February 2018)

scholarly journals Not All Emotions Are Equal: Fear Chemosignals Lower Awareness Thresholds Only for Fearful Faces

2020 ◽  
Vol 45 (7) ◽  
pp. 601-608
Author(s):  
Fábio Silva ◽  
Nuno Gomes ◽  
Sebastian Korb ◽  
Gün R Semin
Keyword(s):  
Facial Expressions ◽  
Visual Processing ◽  
Visual Awareness ◽  
Emotional States ◽  
Body Odor ◽  
Emotional Facial Expressions ◽  
Continuous Flash Suppression ◽  
Fearful Faces ◽  
Processing Stream ◽  
Body Odors

Abstract Exposure to body odors (chemosignals) collected under different emotional states (i.e., emotional chemosignals) can modulate our visual system, biasing visual perception. Recent research has suggested that exposure to fear body odors, results in a generalized faster access to visual awareness of different emotional facial expressions (i.e., fear, happy, and neutral). In the present study, we aimed at replicating and extending these findings by exploring if these effects are limited to fear odor, by introducing a second negative body odor—that is, disgust. We compared the time that 3 different emotional facial expressions (i.e., fear, disgust, and neutral) took to reach visual awareness, during a breaking continuous flash suppression paradigm, across 3 body odor conditions (i.e., fear, disgust, and neutral). We found that fear body odors do not trigger an overall faster access to visual awareness, but instead sped-up access to awareness specifically for facial expressions of fear. Disgust odor, on the other hand, had no effects on awareness thresholds of facial expressions. These findings contrast with prior results, suggesting that the potential of fear body odors to induce visual processing adjustments is specific to fear cues. Furthermore, our results support a unique ability of fear body odors in inducing such visual processing changes, compared with other negative emotional chemosignals (i.e., disgust). These conclusions raise interesting questions as to how fear odor might interact with the visual processing stream, whilst simultaneously giving rise to future avenues of research.

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