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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

Accuracies for all age-matched control participants. Dashed line indicates chance level (25%).
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Figure 3: Accuracies for all age-matched control participants. Dashed line indicates chance level (25%).

Mentions: The results revealed a striking dissociation between DF and the control group, both in terms of accuracy and correct reaction time (see Figure 1). Using a statistic developed by Crawford, Garthwaite, and Porter (2010) to compare the difference score of a single patient to a small control sample, we can confirm that DF's results clearly dissociate from the normal population (two-tailed: p < .001 for accuracy and p < .00001 for reaction time). While the control participants exhibited a robust configural superiority advantage (t(11) = 4.07, p = .002; see Figure 3 for individual performance), DF showed the opposite: she performed better in the isolated line or part condition (two-proportion z-test, z = 3.79, p < .0001). DF's performance is in fact strikingly consistent with the discriminability of patterns of activation measured with fMRI in the early visual cortex of healthy young participants (Kubilius et al., 2011). DF's reaction times also revealed the same reversal, with much faster performance in the isolated line condition, though overall DF's reaction times were much slower than healthy controls (Figure 4).


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)

Accuracies for all age-matched control participants. Dashed line indicates chance level (25%).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Accuracies for all age-matched control participants. Dashed line indicates chance level (25%).
Mentions: The results revealed a striking dissociation between DF and the control group, both in terms of accuracy and correct reaction time (see Figure 1). Using a statistic developed by Crawford, Garthwaite, and Porter (2010) to compare the difference score of a single patient to a small control sample, we can confirm that DF's results clearly dissociate from the normal population (two-tailed: p < .001 for accuracy and p < .00001 for reaction time). While the control participants exhibited a robust configural superiority advantage (t(11) = 4.07, p = .002; see Figure 3 for individual performance), DF showed the opposite: she performed better in the isolated line or part condition (two-proportion z-test, z = 3.79, p < .0001). DF's performance is in fact strikingly consistent with the discriminability of patterns of activation measured with fMRI in the early visual cortex of healthy young participants (Kubilius et al., 2011). DF's reaction times also revealed the same reversal, with much faster performance in the isolated line condition, though overall DF's reaction times were much slower than healthy controls (Figure 4).

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