vrijdag 26 april 2013
maandag 11 maart 2013
Functional specialization and generalization for grouping of stimuli based o...
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Publication year: 2013
Source:NeuroImage, Volume 73
This study was undertaken to learn whether the principle of functional specialization that is evident at the level of the prestriate visual cortex extends to areas that are involved in grouping visual stimuli according to attribute, and specifically according to colour and motion. Subjects viewed, in an fMRI scanner, visual stimuli composed of moving dots, which could be either coloured or achromatic; in some stimuli the moving coloured dots were randomly distributed or moved in random directions; in others, some of the moving dots were grouped together according to colour or to direction of motion, with the number of groupings varying from 1 to 3. Increased activation was observed in area V4 in response to colour grouping and in V5 in response to motion grouping while both groupings led to activity in separate though contiguous compartments within the intraparietal cortex. The activity in all the above areas was parametrically related to the number of groupings, as was the prominent activity in Crus I of the cerebellum where the activity resulting from the two types of grouping overlapped. This suggests (a) that, the specialized visual areas of the prestriate cortex have functions beyond the processing of visual signals according to attribute, namely that of grouping signals according to colour (V4) or motion (V5); (b) that the functional separation evident in visual cortical areas devoted to motion and colour, respectively, is maintained at the level of parietal cortex, at least as far as grouping according to attribute is concerned; and (c) that, by contrast, this grouping-related functional segregation is not maintained at the level of the cerebellum.
Highlights
► Subjects viewed stimuli containing groups defined by motion or colour. ► There was grouping related activity in cerebellum, in prestriate and parietal cortex. ► Activity in parietal cortex, but not cerebellum, was segregated according to modality.Things you can do from here:
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zondag 24 februari 2013
TED: Ami Klin: A new way to diagnose autism - Ami Klin (2011)
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dinsdag 12 februari 2013
PeerJ leads a high-quality, low-cost new breed of open-access publisher
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A one-off fee allows researchers to publish as many papers as they like. The first open access PeerJ articles appear today
We all know by now that traditional academic publishing is in an appalling mess. Locking publicly funded research behind a paywall is completely unacceptable, and happily our government understands this. The Finch Report has rightly mandated that research must be published as open access. So profiteering publishers, seeing the writing on the wall, are offering authors open-access options.
But corporations addicted to profit margins of 32-42% find it hard to give them up. As a result, while the world's leading open-access journal, PLOS ONE, is able to be financially self-sustaining by charging an article processing fee (APC) of $1,350 (£865) (and offering no-questions-asked waivers to authors without APC funding), the legacy publishers charge significantly more for inferior products. Where PLOS ONE imposes no limits on manuscript length, number of figures, use of colour etc., Elsevier's nearly-open-access articles cost $3,000 despite being limited in all these respects. Likewise, Springer's Open Choice costs $3,000 and Taylor & Francis's Open Select costs $2,950.
It is maybe not surprising that the Finch Report's financial estimates assumed average APCs of £1,500-£2,000, and that some academics are baulking at such prices.
Into that landscape come three exciting newcomers that are changing the market much more profoundly than the slow-moving incumbents yet realise. eLIFE is positioned as a highly selective and prestigious open-access alternative to Science and Nature. It published its first articles three months ago. PeerJ is a PLOS ONE-like mega-journal and it publishes its first articles today. Momentum has built further with the announcement of the Open Library of Humanities (OLH) last month, a PLOS-like initiative for the humanities and social sciences.
All three of these new kids on the block are radically innovative, all are moving fast, and all are backed by some serious muscle. eLIFE is sponsored by the Howard Hughes Medical Institute, Max Planck Society and Wellcome Trust; as a result, it's able to waive all APCs while it establishes itself, and may do so indefinitely.
The academic steering committee of the OLH is packed with heavy hitters, and well on course to do for the humanities what PLOS did for the sciences. While the level of its APC has not yet been set, it has been established that no one will be prevented from publishing there by lack of funds.
But it is PeerJ that has the most interesting financial approach. It doesn't exactly have an APC at all, instead charging a one-off fee for a lifetime membership that gives the right to publish repeatedly at no further cost. Membership plans start at $99, which allows you to publish one paper a year, or $299 gets you an infinite plan: publish anything you want, any time you like. (All authors of multi-author papers must be members.)
Sounds crazy, right? How can that be financially sustainable? What kind of idiots would start such a venture?
I'll tell you who: Pete Binfield, who was the editor-in-chief of PLOS ONE as it became the world's biggest journal. There is nobody in the world who knows more about what it takes to run a successful open-access mega-journal. His co-founder is Jason Hoyt, who built much of the phenomenally successful collaborative reference-manager Mendeley.
So they both have great track records. But might their enthusiasm have run away with them? Did wishful thinking persuade them that this utopian approach can work? What kind of idiot would invest in such a business?
I'll tell you who: Internet guru Tim O'Reilly, who founded and runs O'Reilly Media, arguably the world's most respected publisher of programming books, including open-access books. There may be nobody in the world who better understands how to monetise free content.
But the strength of PeerJ goes much deeper than the founders and governing board. The members of the academic board, for example, have five Nobel prizes between them. From top to bottom it's a quality organisation, and that dedication to quality is reflected in the way my own manuscript has been handled.
I, with my colleague Matt Wedel, sent it on 3 December - the day PeerJ submissions opened. We were assigned a handling editor whose own research we greatly respect, and he sent the manuscript to two reviewers. We got an initial decision ("accept with moderate revisions") less than three weeks later, accompanied by two reviews, one of which was particularly helpful and detailed. Our revised manuscript was accepted, and we have since been through two pageproof cycles. All this has happened in time for publication today – only 10 weeks after initial submission. That's by far the fastest any manuscript of mine has ever been handled. It's not unusual for the process to take more than a year.
So now, the resulting paper is free to the world, with all its high-resolution colour illustrations. Best of all, in a move towards increasing transparency, the peer reviews, our response letters and the handling editor's comments are all online alongside the paper. This is good not only because it shows that no corners were cut, but also because the reviewers can receive the credit they deserve for their contributions.
Legacy publishers haven't noticed it yet, but their world is ending. PeerJ handled our paper in a fifth of the time a typical journal would have taken, for one thirtieth the cost, producing a far more useful and even beautiful result, and with a transparent peer-review process.
There is no way the Elseviers and Springers can compete with that. While Elsevier is still trying to figure out what its "sponsored article" licence is, and whether it's even going to be truly open access, PeerJ has appeared out of nowhere and eaten its lunch.
Traditional publishers didn't take PLOS ONE seriously when it launched. By the time they'd finished sneering at it, it had overtaken all their journals for volume and most of them for impact. It looks like PeerJ is going to do the same before they even have time to start sneering. As a palaeontologist, the only conclusion I can draw is that they've been out-evolved.
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maandag 14 januari 2013
Comparing face processing strategies between typically-developed observers a...
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Publication year: 2013
Source:Vision Research
In the present study we modified the standard classification image method by subsampling visual stimuli to provide us with a technique capable of examining an individual's face-processing strategy in detail with fewer trials. Experiment 1 confirmed that one testing session (1450 trials) was sufficient to produce classification images that were qualitatively similar to those obtained previously with 10,000 trials (Sekuler, Gaspar, Gold, & Bennett, 2004). Experiment 2 used this method to compare classification images obtained from observers with autism spectrum disorders (ASD) and typically-developing (TD) observers. As was found in Experiment 1, classification images obtained from TD observers suggested that they all discriminated faces based on information conveyed by pixels in the eyes/brow region. In contrast, classification images obtained from ASD observers suggested that they used different perceptual strategies: three out of five ASD observers used a typical strategy of making use of information in the eye/brow region, but two used an atypical strategy that relied on information in the forehead region. The advantage of using the response classification technique is that there is no restriction to specific theoretical perspectives or a priori hypotheses, which enabled us to see unexpected strategies, like ASD's forehead strategy, and thus showed this technique is particularly useful in the examination of special populations.
Highlights
► We modified classification image technique working fine with fewer trials than ever. ► The technique was applied to autistic individuals to show face-processing strategy. ► We showed unexpected autistic observer's face-processing strategy on forehead.Things you can do from here:
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zaterdag 5 januari 2013
A bit about patches, textures, and masks in PsychoPy
PsychoPy is a powerful Python library for creating the type of stimuli that are frequently used in psychological and neuroscientific experiments. I use it all the time, mostly from within OpenSesame, but I remember that I initially found working with PsychoPy quite daunting. This is because PsychoPy takes a very different approach to stimulus generation than most people are used to. You have to think in terms of patches, textures, and, masks, rather than in conventional drawing primitives, such as rectangles and lines (although newer versions of PsychoPy also support these drawing primitives). Therefore, I decided to write a short tutorial that explains the basics of working with PsychoPy.
donderdag 3 januari 2013
The Time Course of Perceptual Grouping in Natural Scenes
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Visual perception starts with localized filters that subdivide the image into fragments that undergo separate analyses. The visual system has to reconstruct objects by grouping image fragments that belong to the same object. A widely held view is that perceptual grouping occurs in parallel across the visual scene and without attention. To test this idea, we measured the speed of grouping in pictures of animals and vehicles. In a classification task, these pictures were categorized efficiently. In an image-parsing task, participants reported whether two cues fell on the same or different objects, and we measured reaction times. Despite the participants' fast object classification, perceptual grouping required more time if the distance between cues was larger, and we observed an additional delay when the cues fell on different parts of a single object. Parsing was also slower for inverted than for upright objects. These results imply that perception starts with rapid object classification and that rapid classification is followed by a serial perceptual grouping phase, which is more efficient for objects in a familiar orientation than for objects in an unfamiliar orientation.
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