Comparing face processing strategies between typically-developed observers a...

 

 

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Comparing face processing strategies between typically-developed observers and observers with autism using sub-sampled-pixels presentation in response classification technique

via ScienceDirect Publication: Vision Research on 1/14/13

Available online 12 January 2013
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.

 

 

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A bit about patches, textures, and masks in PsychoPy

A thorough guide on drawing stimuli in psychopy.
 
 

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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.

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The Time Course of Perceptual Grouping in Natural Scenes

 

 

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The Time Course of Perceptual Grouping in Natural Scenes

via Psychological Science current issue by Korjoukov, I., Jeurissen, D., Kloosterman, N. A., Verhoeven, J. E., Scholte, H. S., Roelfsema, P. R. on 12/14/12

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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Visual Aesthetics and Human Preference

 

 

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Visual Aesthetics and Human Preference

via Annual Reviews: Annual Review of Psychology: Table of Contents by announce@annualreviews.org (Stephen E. Palmer et al) on 1/2/13

Annual Review of Psychology Volume 64, Page 77-107, January 2013.

 

 

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