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Configural Gestalts remain nothing more than the sum of their parts in visual agnosia.

de-Wit LH, Kubilius J, Op de Beeck HP, Wagemans J - Iperception (2013)

Bottom Line: We report converging evidence that higher stages of the visual system are critically required for the whole to become more than the sum of its parts by studying patient DF with visual agnosia using a configural superiority paradigm.Furthermore, by comparing DF's performance to earlier neuroimaging and novel modeling work, we found a compelling consistency between her performance and representations in the early visual areas, which are spared in this patient.The reversed pattern of performance in this patient highlights that in some cases visual Gestalts do not emerge early on without processing in higher visual areas.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Experimental Psychology, KU Leuven, Leuven, Belgium; e-mail: Lee.deWit@ppw.kuleuven.be.

ABSTRACT
We report converging evidence that higher stages of the visual system are critically required for the whole to become more than the sum of its parts by studying patient DF with visual agnosia using a configural superiority paradigm. We demonstrate a clear dissociation between this patient and normal controls such that she could more easily report information about parts, demonstrating a striking reversal of the normal configural superiority effect. Furthermore, by comparing DF's performance to earlier neuroimaging and novel modeling work, we found a compelling consistency between her performance and representations in the early visual areas, which are spared in this patient. The reversed pattern of performance in this patient highlights that in some cases visual Gestalts do not emerge early on without processing in higher visual areas. More broadly, this study demonstrates how neuropsychological patients can be used to unmask representations maintained at early stages of processing.

No MeSH data available.


Related in: MedlinePlus

Discriminability between stimuli in simple V1 models: Pixelwise, Gabor Jet, and HMAX C1. GaborJet and HMAX layer C1 outputs resembled both DF's performance and discriminability of stimuli in the primary visual cortex (V1) of young participants tested in Kubilius et al. (2011). Pixelwise model exhibited only a minute advantage of parts versus wholes (8.87×10−3 vs. 8.54×10−3) due to a large number of identical gray background pixels.
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Figure 2: Discriminability between stimuli in simple V1 models: Pixelwise, Gabor Jet, and HMAX C1. GaborJet and HMAX layer C1 outputs resembled both DF's performance and discriminability of stimuli in the primary visual cortex (V1) of young participants tested in Kubilius et al. (2011). Pixelwise model exhibited only a minute advantage of parts versus wholes (8.87×10−3 vs. 8.54×10−3) due to a large number of identical gray background pixels.

Mentions: This result is consistent with the hypothesis that early visual cortex is not sufficient to produce compelling Gestalt representations. It might appear counterintuitive that DF should not only reveal no configural advantage, but also perform better in the isolated line condition than in the configural condition. To address this issue further, we compared DF's performance to different models of V1 that apply Gabor filters at various orientations, spatial frequencies, and scales (Figure 1; Riesenhuber & Poggio, 1999; Xu, Yue, Lescroart, Biederman, & Kim, 2009; see Figure 2 for comparisons to other models). Just like DF, these models discriminated better between parts than whole shapes, indicating that at an early stage of processing, the additional corner units simply add distracting noise or clutter that requires further processing to be usefully organized as a genuine Gestalt.


Configural Gestalts remain nothing more than the sum of their parts in visual agnosia.

de-Wit LH, Kubilius J, Op de Beeck HP, Wagemans J - Iperception (2013)

Discriminability between stimuli in simple V1 models: Pixelwise, Gabor Jet, and HMAX C1. GaborJet and HMAX layer C1 outputs resembled both DF's performance and discriminability of stimuli in the primary visual cortex (V1) of young participants tested in Kubilius et al. (2011). Pixelwise model exhibited only a minute advantage of parts versus wholes (8.87×10−3 vs. 8.54×10−3) due to a large number of identical gray background pixels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4129382&req=5

Figure 2: Discriminability between stimuli in simple V1 models: Pixelwise, Gabor Jet, and HMAX C1. GaborJet and HMAX layer C1 outputs resembled both DF's performance and discriminability of stimuli in the primary visual cortex (V1) of young participants tested in Kubilius et al. (2011). Pixelwise model exhibited only a minute advantage of parts versus wholes (8.87×10−3 vs. 8.54×10−3) due to a large number of identical gray background pixels.
Mentions: This result is consistent with the hypothesis that early visual cortex is not sufficient to produce compelling Gestalt representations. It might appear counterintuitive that DF should not only reveal no configural advantage, but also perform better in the isolated line condition than in the configural condition. To address this issue further, we compared DF's performance to different models of V1 that apply Gabor filters at various orientations, spatial frequencies, and scales (Figure 1; Riesenhuber & Poggio, 1999; Xu, Yue, Lescroart, Biederman, & Kim, 2009; see Figure 2 for comparisons to other models). Just like DF, these models discriminated better between parts than whole shapes, indicating that at an early stage of processing, the additional corner units simply add distracting noise or clutter that requires further processing to be usefully organized as a genuine Gestalt.

Bottom Line: We report converging evidence that higher stages of the visual system are critically required for the whole to become more than the sum of its parts by studying patient DF with visual agnosia using a configural superiority paradigm.Furthermore, by comparing DF's performance to earlier neuroimaging and novel modeling work, we found a compelling consistency between her performance and representations in the early visual areas, which are spared in this patient.The reversed pattern of performance in this patient highlights that in some cases visual Gestalts do not emerge early on without processing in higher visual areas.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Experimental Psychology, KU Leuven, Leuven, Belgium; e-mail: Lee.deWit@ppw.kuleuven.be.

ABSTRACT
We report converging evidence that higher stages of the visual system are critically required for the whole to become more than the sum of its parts by studying patient DF with visual agnosia using a configural superiority paradigm. We demonstrate a clear dissociation between this patient and normal controls such that she could more easily report information about parts, demonstrating a striking reversal of the normal configural superiority effect. Furthermore, by comparing DF's performance to earlier neuroimaging and novel modeling work, we found a compelling consistency between her performance and representations in the early visual areas, which are spared in this patient. The reversed pattern of performance in this patient highlights that in some cases visual Gestalts do not emerge early on without processing in higher visual areas. More broadly, this study demonstrates how neuropsychological patients can be used to unmask representations maintained at early stages of processing.

No MeSH data available.


Related in: MedlinePlus