-
PloS One 2014Does becoming aware of a change to a purely visual stimulus necessarily cause the observer to be able to identify or localise the change or can change detection occur in...
Does becoming aware of a change to a purely visual stimulus necessarily cause the observer to be able to identify or localise the change or can change detection occur in the absence of identification or localisation? Several theories of visual awareness stress that we are aware of more than just the few objects to which we attend. In particular, it is clear that to some extent we are also aware of the global properties of the scene, such as the mean luminance or the distribution of spatial frequencies. It follows that we may be able to detect a change to a visual scene by detecting a change to one or more of these global properties. However, detecting a change to global property may not supply us with enough information to accurately identify or localise which object in the scene has been changed. Thus, it may be possible to reliably detect the occurrence of changes without being able to identify or localise what has changed. Previous attempts to show that this can occur with natural images have produced mixed results. Here we use a novel analysis technique to provide additional evidence that changes can be detected in natural images without also being identified or localised. It is likely that this occurs by the observers monitoring the global properties of the scene.
Topics: Adult; Color Perception; Female; Humans; Male; Photic Stimulation; Task Performance and Analysis; Visual Perception; Young Adult
PubMed: 24454727
DOI: 10.1371/journal.pone.0084490 -
Nature Communications Aug 2016Humans, including infants, and many other species have a capacity for rapid, nonverbal estimation of numerosity. However, the mechanisms for number perception are still...
Humans, including infants, and many other species have a capacity for rapid, nonverbal estimation of numerosity. However, the mechanisms for number perception are still not clear; some maintain that the system calculates numerosity via density estimates-similar to those involved in texture-while others maintain that more direct, dedicated mechanisms are involved. Here we show that provided that items are not packed too densely, human subjects are far more sensitive to numerosity than to either density or area. In a two-dimensional space spanning density, area and numerosity, subjects spontaneously react with far greater sensitivity to changes in numerosity, than either area or density. Even in tasks where they were explicitly instructed to make density or area judgments, they responded spontaneously to number. We conclude, that humans extract number information, directly and spontaneously, via dedicated mechanisms.
Topics: Adult; Cues; Discrimination, Psychological; Female; Humans; Judgment; Male; Mathematical Concepts; Pattern Recognition, Visual; Visual Perception
PubMed: 27555562
DOI: 10.1038/ncomms12536 -
Journal of Neurophysiology Aug 2007It is well known that electrical activation of striate cortex (area V1) can disrupt visual behavior. Based on this knowledge, we discovered that electrical... (Review)
Review
It is well known that electrical activation of striate cortex (area V1) can disrupt visual behavior. Based on this knowledge, we discovered that electrical microstimulation of V1 in macaque monkeys delays saccadic eye movements when made to visual targets located in the receptive field of the stimulated neurons. This review discusses the following issues. First, the parameters that affect the delay of saccades by microstimulation of V1 are reviewed. Second, the excitability properties of the V1 elements mediating the delay are discussed. Third, the properties that determine the size and shape of the region of visual space affected by stimulation of V1 are described. This region is called a delay field. Fourth, whether the delay effect is mainly due to a disruption of the visual signal transmitted through V1 or whether it is a disturbance of the motor signal transmitted between V1 and the brain stem saccade generator is investigated. Fifth, the properties of delay fields are used to estimate the number of elements activated directly by electrical microstimulation of macaque V1. Sixth, these properties are used to make inferences about the characteristics of visual percepts induced by such stimulation. Seventh, the disruptive effects of V1 stimulation in monkeys and humans are compared. Eighth, a cortical mechanism to account for the disruptive effects of V1 stimulation is proposed. Finally, these effects are related to normal vision.
Topics: Animals; Brain Mapping; Dominance, Ocular; Electric Stimulation; Humans; Macaca mulatta; Reaction Time; Saccades; Visual Cortex; Visual Fields; Visual Perception
PubMed: 17567774
DOI: 10.1152/jn.00285.2007 -
Vision Research Nov 2015
Topics: Attention; Computer Simulation; Humans; Visual Perception
PubMed: 26420739
DOI: 10.1016/j.visres.2015.09.007 -
Current Biology : CB Oct 2004Visual attention is attracted by salient stimuli that 'pop out' from their surroundings. Attention can also be voluntarily directed to objects of current importance to... (Review)
Review
Visual attention is attracted by salient stimuli that 'pop out' from their surroundings. Attention can also be voluntarily directed to objects of current importance to the observer. What happens in the brain when these two processes interact?
Topics: Attention; Color Perception; Humans; Models, Psychological; Pattern Recognition, Visual; Time Factors; Visual Fields; Visual Pathways; Visual Perception
PubMed: 15458666
DOI: 10.1016/j.cub.2004.09.041 -
The Journal of Neuroscience : the... Jan 2011Early visual areas are required for conscious visual perception, but recent evidence suggests that parts of the frontal lobe might also play a key role. However, it...
Early visual areas are required for conscious visual perception, but recent evidence suggests that parts of the frontal lobe might also play a key role. However, it remains unclear whether frontal brain areas are involved in visual perception or merely use information from visual regions to drive behavior. One such frontal cortical area, the frontal-eye field (FEF), has been shown to have fast visual responses, thought to reflect mostly low-level visual processing, and delayed responses that correlate with perceptual reports. The latter observation is consistent with the idea that FEF uses visual information from (slower) visual regions to guide behavior. Here we ask whether fast visual responses in FEF also carry information related to the perceptual state of animals. We recorded single-cell activity in two monkeys trained to report the presence or absence of a visual target under conditions that evoke the illusory disappearance of the target (motion-induced blindness). We found that fast responses in FEF strongly correlated with the perceptual report of the animal. It is unlikely that short-latency perceptually correlated activity is inherited from early visual areas, since response latencies in FEF are shorter than those of visual areas with perceptually correlated activity. These results suggest that frontal brain areas are involved in generating the contents of visual perception.
Topics: Animals; Color Perception; Consciousness; Evoked Potentials, Visual; Macaca mulatta; Male; Motion Perception; Photic Stimulation; Prefrontal Cortex; Reaction Time; Time Factors; Vision, Ocular; Visual Fields; Visual Perception
PubMed: 21209190
DOI: 10.1523/JNEUROSCI.3620-10.2011 -
Neuron Dec 1999Physiological, computational, and psychophysical studies of stereopsis have assumed that the perceived surface structure of binocularly viewed images is primarily... (Clinical Trial)
Clinical Trial Randomized Controlled Trial
Physiological, computational, and psychophysical studies of stereopsis have assumed that the perceived surface structure of binocularly viewed images is primarily specified by the pattern of binocular disparities in the two eyes' views. A novel set of stereoscopic phenomena are reported that demonstrate the insufficiency of this view. It is shown that the visual system computes the contrast relationships along depth discontinuities to infer the depth, lightness, and opacity of stereoscopically viewed surfaces. A novel theoretical framework is introduced to explain these results. It is argued that the visual system contains mechanisms that enforce two principles of scene interpretation: a generic view principle that determines qualitative scene geometry, and anchoring principles that determine how image data are quantitatively partitioned between different surface attributes.
Topics: Algorithms; Brain Mapping; Depth Perception; Humans; Photic Stimulation; Vision Disparity; Vision, Monocular; Visual Perception
PubMed: 10624955
DOI: 10.1016/s0896-6273(00)81039-9 -
Scientific Reports Apr 2024The biographies of some celebrated artists are marked by accounts that paint a far from beautiful portrait. Does this negative-social knowledge influence the aesthetic...
The biographies of some celebrated artists are marked by accounts that paint a far from beautiful portrait. Does this negative-social knowledge influence the aesthetic experience of an artwork? Does an artist's fame protect their paintings from such an influence? We present two preregistered experiments examining the effect of social-emotional biographical knowledge about famous and unknown artists on the reception and perception of their paintings, using aesthetic ratings and neurocognitive measures. In Experiment 1, paintings attributed to artists characterised by negative biographical information were liked less, evoked greater feelings of arousal and were judged lower in terms of quality, than paintings by artists associated with neutral information. No modulation of artist renown was found. Experiment 2 fully replicated these behavioural results and revealed that paintings by artists associated with negative social-emotional knowledge also elicited enhanced early brain activity related to visual perception (P1) and early emotional arousal (early posterior negativity; EPN). Together, the findings suggest that negative knowledge about famous artists can shape not only explicit aesthetic evaluations, but may also penetrate the perception of the artwork itself.
Topics: Paintings; Visual Perception; Emotions
PubMed: 38584222
DOI: 10.1038/s41598-024-58697-1 -
Vision Research May 2011Crowding (mutual scrambling of nearby peripheral stimuli) has several known asymmetries. We explored these and other asymmetries systematically across the visual field....
Crowding (mutual scrambling of nearby peripheral stimuli) has several known asymmetries. We explored these and other asymmetries systematically across the visual field. Crowding strength for 16 target (Gabor) positions in the visual field (8 directions × 2 eccentricities) were determined by positioning a plaid mask made of two transparently overlaid Gabors either inward, outward, clockwise, or counter-clockwise around the target. Overall, we found a surprisingly large individual variation in crowding strength appearing as idiosyncratic hotspots across the visual field. No correlations were found between the idiosyncratic variations of crowding and visual acuity either across the visual field or across subjects. When averaged across observers the results replicated most of the previously reported asymmetries of crowding. No new types of asymmetries were observed, but we found that the inward-outward asymmetry of crowding is present only along the horizontal meridian. Most surprisingly, we discovered that this asymmetry increases two-fold, if the observer is forced to attend to both left and right visual fields. This indicates that besides other factors attention allocation has a strong effect on the crowding asymmetry.
Topics: Adult; Attention; Female; Humans; Male; Perceptual Masking; Photic Stimulation; Psychophysics; Visual Acuity; Visual Fields; Visual Perception
PubMed: 21439309
DOI: 10.1016/j.visres.2011.03.001 -
Altered short-term neural plasticity related to schizotypal traits: Evidence from visual adaptation.Schizophrenia Research May 2019Abnormalities in synaptic plasticity are argued to underlie the neural dysconnectivity observed in schizophrenia. One way to measure synaptic plasticity is through...
Abnormalities in synaptic plasticity are argued to underlie the neural dysconnectivity observed in schizophrenia. One way to measure synaptic plasticity is through sensory adaptation, whereby sensory neurons exhibit reduced sensitivity after sustained stimulus exposure. Evidence for decreased adaptation in individuals with schizophrenia is currently inconclusive, possibly due to heterogeneity in clinical and medication status across samples. Here we circumvent these confounds by examining whether altered adaptation is represented sub-clinically in the general population. To test this we used three paradigms from visual perception research that provide a precise and non-invasive index of adaptation in the visual system. Two paradigms involve a class of illusory percepts termed visual aftereffects. The third relies on a visual phenomenon termed binocular rivalry, where incompatible stimuli are presented to the two eyes and observers alternate between perceiving exclusively one stimulus or a combination of the two (i.e. mixed perception). We analyzed the strength and dynamics of visual adaptation in these paradigms, in relation to schizotypy. Our results showed that increased schizotypal traits were related to reduced orientation, but not luminance, aftereffect strength (Exp. 1). Further, increased schizotypy was related to a greater proportion of mixed perception during binocular rivalry (Exp. 1 and 2). Given that visual adaption is well understood at cellular and computational levels, our data suggest that short-term plasticity in the visual system can provide important information about the disease mechanisms of schizophrenia.
Topics: Adaptation, Physiological; Adult; Female; Humans; Male; Neuronal Plasticity; Pattern Recognition, Visual; Schizotypal Personality Disorder; Vision, Binocular; Visual Perception; Young Adult
PubMed: 29685421
DOI: 10.1016/j.schres.2018.04.013