News and Events

Increased readiness for adaptation and faster alternation rates under binocular rivalry in children

Publication Type:

Journal Article

Source:

Frontiers in Human Neuroscience, Volume 5, Issue 128 (2011)

ISBN:

1662-5161

URL:

http://www.frontiersin.org/Human_Neuroscience/10.3389/fnhum.2011.00128/abstract

Keywords:

adaptation, binocular rivalry, cumulative history, dominance time, human development, multi-stable perception

Abstract:

<p>BACKGROUND: Binocular rivalry in childhood has poorly been investigated in the past. Information is scarce with respect to infancy, and there is a complete lack of data on the development of binocular rivalry beyond the first 4-5 years of age. In this study, we are attempting to fill this gap by investigating the developmental trends in binocular rivalry in pre-puberty. We employ a classic behavioral paradigm with orthogonal gratings, and introduce novel statistical measures (after Pastukhov and Braun) to analyze the data. These novel measures provide a sensitive tool to estimate the impact of the history of perceptual alternations on future alternations. We found that the cumulative history of perceptual alternations has an impact on future percepts, and that this impact is significantly stronger and faster in children than in adults. Assessment of the ?cumulative history? and its characteristic time-constant helps us to take a look at the adaptive states of the visual system under multi-stable perception, and brings us closer to establishing a possible developmental scenario of binocular rivalry: children adapt faster and stronger, and this increased readiness for adaption seems to be associated with faster alternation rates.</p>

Neuronal activity in human primary visual cortex correlates with perception during binocular rivalry.

Publication Type:

Journal Article

Source:

Nature neuroscience, Nature Publishing Group, Volume 3, Number 11, p.1153–9 (2000)

URL:

http://www.nature.com/neuro/journal/v3/n11/full/nn1100\_1153.html

Keywords:

Algorithms, Binocular, Binocular: physiology, Humans, Least-Squares Analysis, Magnetic Resonance Imaging, Pattern Recognition, Photic Stimulation, Photic Stimulation: methods, Vision, Visual, Visual Cortex, Visual Cortex: physiology, Visual Perception, Visual Perception: physiology, Visual: physiology

Abstract:

During binocular rivalry, two incompatible monocular images compete for perceptual dominance, with one pattern temporarily suppressed from conscious awareness. We measured fMRI signals in early visual cortex while subjects viewed rival dichoptic images of two different contrasts; the contrast difference served as a 'tag' for the neuronal representations of the two monocular images. Activity in primary visual cortex (V1) increased when subjects perceived the higher contrast pattern and decreased when subjects perceived the lower contrast pattern. These fluctuations in V1 activity during rivalry were about 55% as large as those evoked by alternately presenting the two monocular images without rivalry. The rivalry-related fluctuations in V1 activity were roughly equal to those observed in other visual areas (V2, V3, V3a and V4v). These results challenge the view that the neuronal mechanisms responsible for binocular rivalry occur primarily in later visual areas.

Further evidence for the spread of attention during contour grouping: a reply to Crundall, Dewhurst, and Underwood (2008).

Publication Type:

Journal Article

Source:

Attention, perception & psychophysics, Volume 72, Number 3, p.849–62 (2010)

URL:

http://www.ncbi.nlm.nih.gov/pubmed/20358648

Keywords:

Attention, Awareness, Humans

Abstract:

In a contour-grouping task, subjects decide whether contour elements belong to the same or different curves. Houtkamp, Spekreijse, and Roelfsema (2003) demonstrated that object-based attention spreads gradually over contour elements that have to be grouped in perception. Crundall, Dewhurst, and Underwood (2008) challenged this spreading-attention model and suggested that attention in the contour-grouping task is not object based but rather has the shape of a zoom lens that moves along the relevant curve. To distinguish between object-based and spatial attention, they changed the stimulus and measured the impact on performance. Subjects were not able to correct for changes at the start of the relevant curve toward the end of the trial. They suggested that attention did not stay at the beginning of the curve, in accordance with a moving zoom lens model. Here, we examine the task of Crundall et al. and find that subjects perceive the changes but fail to correct their response. By measuring change detection directly, we find that performance is much better for the start of the relevant curve than for an irrelevant curve, at all times. Our findings do not support the zoom lens model but provide further support for the spreading attention model.

Gender differences in the functional organization of the brain for working memory.

Publication Type:

Journal Article

Source:

Neuroreport, Volume 11, Number 11, p.2581–5 (2000)

URL:

http://journals.lww.com/neuroreport/pages/articleviewer.aspx?year=2000&issue=08030&article=00046&type=abstract

Keywords:

Adult, Brain Mapping, Cerebral Cortex, Cerebral Cortex: anatomy & histology, Cerebral Cortex: physiology, Female, Functional Laterality, Functional Laterality: physiology, Humans, Magnetic Resonance Imaging, Male, Memory, Neuropsychological Tests, Neuropsychological Tests: statistics & numerical d, Psychomotor Performance, Psychomotor Performance: physiology, Sex Factors, Short-Term, Short-Term: physiology

Abstract:

Gender differences in brain activation during working memory tasks were examined with fMRI. Seventeen right-handed subjects (nine males, eight females) were studied with four different verbal working memory tasks of varying difficulty using whole brain echo-planar fMRI. Consistent with prior studies, we observed activation of the lateral prefrontal cortices (LPFC), the parietal cortices (PC), and additionally, caudate activation in both sexes. The volume of activated brain tissue increased with increasing task difficulty. For all four tasks, the male subjects showed bilateral activation or right-sided dominance (LPFC, PC and caudate), whereas females showed activation predominantly in the left hemisphere. The task performance data demonstrated higher accuracy and slightly slower reaction times for the female subjects. Our results show a highly significant (p < 0.001) gender differences in the functional organization of the brain for working memory. These gender-specific differences in functional organization of the brain may be due to gender-differences in problem solving strategies or the neurodevelopment. Therefore, gender matching or stratification is required for studies of brain function using imaging techniques.

Contrast thresholds for component motion with full and poor attention.

Publication Type:

Journal Article

Source:

Journal of Vision, Volume 7, Number 3, p.1–15 (2007)

URL:

http://journalofvision.org/7/3/1/

Keywords:

component motion, luminance contra, pattern motion

Abstract:

We compare luminance-contrast-masking thresholds for fully and poorly attended stimuli, controlling attention with a demanding concurrent task. We use dynamic displays composed of discrete spatiotemporal wavelets, comparing three conditions (“single,” “parallel,” and “random”). In contrast to static displays, we do not find that attention modulates the “dipper” regime for masks of low luminance contrast. Nor does attention alter direction-selective masking by multiple wavelets moving in random directions, a condition designed to isolate effects on component motion. However, direction-selective masking by multiple wavelets moving in parallel is significantly reduced by attention. As the latter condition is expected to excite both component and pattern motion mechanisms, this implies that attention may alter the visual representation of pattern motion. In addition, attention exhibits its well-known effect of reducing lateral masking between nearby spatiotemporal wavelets.

Attentional effects on contrast detection in the presence of surround masks.

Publication Type:

Journal Article

Source:

Vision research, Volume 40, Number 27, p.3717–24 (2000)

URL:

http://www.sciencedirect.com/science/article/pii/S0042698900002182

Keywords:

Attention, Attention: physiology, Contrast Sensitivity, Contrast Sensitivity: physiology, Humans, Orientation, Orientation: physiology, Perceptual Masking, Perceptual Masking: physiology, Psychophysics

Abstract:

We studied how attention affects contrast detection performance when the target is surrounded by mask elements. In each display quadrant we presented a hexagon of six vertical Gabor patches (the 'surround'). Only one of the hexagons contained a central Gabor patch (the 'target') and the task was to report that quadrant (spatial four-alternative-forced choice). Attention was manipulated by means of a double-task paradigm: in one condition observers had to perform concurrently a central letter-discrimination task, and the contrast-detection task was then only poorly attended, while attention was fully available in the other condition. We find that under poorly attended conditions targets can be detected only when the target contrast exceeds the surround contrast (contrast popout) or when the target orientation differs from the surround orientation by more than 10-15 degrees (orientation popout). When the target orientation is similar to the surround orientation, attention can reduce the contrast detection thresholds in some cases more than four-fold, demonstrating a very strong attentional effect.

The effect of items in working memory on the deployment of attention and the eyes during visual search.

Publication Type:

Journal Article

Source:

Journal of experimental psychology. Human perception and performance, Volume 32, Number 2, p.423–42 (2006)

URL:

http://psycnet.apa.org/journals/xhp/32/2/423/

Keywords:

Adolescent, Adult, Analysis of Variance, Attention, Attention: physiology, Exploratory Behavior, Exploratory Behavior: physiology, Eye Movements, Eye Movements: physiology, Female, Field Dependence-Independence, Humans, Male, Memory, Mental Processes, Mental Processes: physiology, Photic Stimulation, Photic Stimulation: methods, Short-Term, Short-Term: physiology, Spatial Behavior, Spatial Behavior: physiology, Visual Perception, Visual Perception: physiology

Abstract:

Paying attention to an object facilitates its storage in working memory. The authors investigate whether the opposite is also true: whether items in working memory influence the deployment of attention. Participants performed a search for a prespecified target while they held another item in working memory. In some trials this memory item was present in the search display as a distractor. Such a distractor has no effect on search time if the search target is in the display. In that case, the item in working memory is unlikely to be selected as a target for an eye movement, and if the eyes do land on it, fixation duration is short. In the absence of the target, however, there is a small but significant effect of the memory item on search time. The authors conclude that the target for visual search has a special status in working memory that allows it to guide attention. Guidance of attention by other items in working memory is much weaker and can be observed only if the search target is not present in the display.

A quantitative model relating visual neuronal activity to psychophysical thresholds

Publication Type:

Journal Article

Source:

Neurocomputing, Volume 26-27, p.743–748 (1999)

URL:

http://www.sciencedirect.com/science/article/pii/S092523129800143X

Keywords:

Non-linear interactions

Abstract:

We investigate how a simple, physiologically motivated three-stage neuronal model can establish a quantitative relationship between activities in small populations of simulated early visual neurons and human psychophysical thresholds. The model consists of: First, a bank of linear filters tuned for orientation and spatial period; second, non-linear interactions between filters; and, third, a statistically efficient decision stage. The model quantitatively reproduces human thresholds for five classical pattern discrimination tasks, using a unique set of automatically determined parameters. The resulting model components are all plausible in terms of putative neuronal correlates.

Revisiting spatial vision: toward a unifying model.

Publication Type:

Journal Article

Source:

Journal of the Optical Society of America. A, Optics, image science, and vision, Volume 17, Number 11, p.1899–917 (2000)

URL:

http://www.opticsinfobase.org/abstract.cfm?URI=JOSAA-17-11-1899

Keywords:

Biological, Computer Simulation, Humans, Models, Psychophysics, Space Perception, Space Perception: physiology, Visual Perception, Visual Perception: physiology

Abstract:

We report contrast detection, contrast increment, contrast masking, orientation discrimination, and spatial frequency discrimination thresholds for spatially localized stimuli at 4 degrees of eccentricity. Our stimulus geometry emphasizes interactions among overlapping visual filters and differs from that used in previous threshold measurements, which also admits interactions among distant filters. We quantitatively account for all measurements by simulating a small population of overlapping visual filters interacting through divisive inhibition. We depart from previous models of this kind in the parameters of divisive inhibition and in using a statistically efficient decision stage based on Fisher information. The success of this unified account suggests that, contrary to Bowne [Vision Res. 30, 449 (1990)], spatial vision thresholds reflect a single level of processing, perhaps as early as primary visual cortex.

Brain areas specific for attentional load in a motion-tracking task.

Publication Type:

Journal Article

Source:

Journal of cognitive neuroscience, Volume 13, Number 8, p.1048–58 (2001)

URL:

http://www.mitpressjournals.org/doi/abs/10.1162/089892901753294347

Keywords:

Adult, Attention, Attention: physiology, Behavior, Brain, Brain Mapping, Brain: physiology, Female, Humans, Magnetic Resonance Imaging, Male, Motion Perception, Motion Perception: physiology, Pursuit, Reproducibility of Results, Smooth, Smooth: physiology, Visual Perception, Visual Perception: physiology

Abstract:

Although visual attention is known to modulate brain activity in the posterior parietal, prefrontal, and visual sensory areas, the unique roles of these areas in the control of attentional resources have remained unclear. Here, we report a dissociation in the response profiles of these areas. In a parametric functional magnetic resonance imaging (fMRI) study, subjects performed a covert motion-tracking task, in which we manipulated "attentional load" by varying the number of tracked balls. While strong effects of attention–independent of attentional load–were widespread, robust linear increases of brain activity with number of balls tracked were seen primarily in the posterior parietal areas, including the intraparietal sulcus (IPS) and superior parietal lobule (SPL). Thus, variations in attentional load revealed different response profiles in sensory areas as compared to control areas. Our results suggest a general role for posterior parietal areas in the deployment of visual of attentional resources.

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