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Feature-Based Change Detection Reveals Inconsistent Individual Differences in Visual Working Memory Capacity.

Ambrose JP, Wijeakumar S, Buss AT, Spencer JP - Front Syst Neurosci (2016)

Bottom Line: As expected, capacity was significantly lower for the shape dimension.Similarly, participants with a stronger BOLD response for color also showed a strong neural response for shape within the lateral occipital cortex, intraparietal sulcus (IPS), and superior IPS.Although there were robust individual differences in the behavioral and neural measures, we found little evidence of systematic brain-behavior correlations across feature dimensions.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Mathematics and Computational Sciences, University of Iowa, Iowa City IA, USA.

ABSTRACT
Visual working memory (VWM) is a key cognitive system that enables people to hold visual information in mind after a stimulus has been removed and compare past and present to detect changes that have occurred. VWM is severely capacity limited to around 3-4 items, although there are robust individual differences in this limit. Importantly, these individual differences are evident in neural measures of VWM capacity. Here, we capitalized on recent work showing that capacity is lower for more complex stimulus dimension. In particular, we asked whether individual differences in capacity remain consistent if capacity is shifted by a more demanding task, and, further, whether the correspondence between behavioral and neural measures holds across a shift in VWM capacity. Participants completed a change detection (CD) task with simple colors and complex shapes in an fMRI experiment. As expected, capacity was significantly lower for the shape dimension. Moreover, there were robust individual differences in behavioral estimates of VWM capacity across dimensions. Similarly, participants with a stronger BOLD response for color also showed a strong neural response for shape within the lateral occipital cortex, intraparietal sulcus (IPS), and superior IPS. Although there were robust individual differences in the behavioral and neural measures, we found little evidence of systematic brain-behavior correlations across feature dimensions. This suggests that behavioral and neural measures of capacity provide different views onto the processes that underlie VWM and CD. Recent theoretical approaches that attempt to bridge between behavioral and neural measures are well positioned to address these findings in future work.

No MeSH data available.


Average percent BOLD signal change over the LOCC, LVOC, RIPS, RsIPS, and RfsMFG ROIs across set size for shape (blue) and color (orange) trials. Responses were significantly higher for color at set sizes 3 and 6. Error bars depict ± 1/2 SE.
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Figure 4: Average percent BOLD signal change over the LOCC, LVOC, RIPS, RsIPS, and RfsMFG ROIs across set size for shape (blue) and color (orange) trials. Responses were significantly higher for color at set sizes 3 and 6. Error bars depict ± 1/2 SE.

Mentions: The remaining five clusters showed an increasing pattern across set size, with a decline at set size 6. Data from these clusters were analyzed together in a three-factor ANOVA with Set Size, Dimension, and Cluster as factors. There was a significant main effect of SS, F(5,380) = 4.48, p < 0.001, and a significant SS × Dimension interaction, F(5,380) = 2.40, p < 0.05. The interaction effect is shown in Figure 4. The BOLD response for the Color dimension rises more steeply and remains high across set sizes 3–6. By contrast, the BOLD response for the Shape dimension rises more gradually and falls off dramatically at set size 6. Post hoc tests determined that the BOLD response for the Color dimension was significantly greater than the Shape dimension at SS3 and SS6, p < 0.05. This is consistent with behavioral results that showed greater Max K for Color than for Shape.


Feature-Based Change Detection Reveals Inconsistent Individual Differences in Visual Working Memory Capacity.

Ambrose JP, Wijeakumar S, Buss AT, Spencer JP - Front Syst Neurosci (2016)

Average percent BOLD signal change over the LOCC, LVOC, RIPS, RsIPS, and RfsMFG ROIs across set size for shape (blue) and color (orange) trials. Responses were significantly higher for color at set sizes 3 and 6. Error bars depict ± 1/2 SE.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4835449&req=5

Figure 4: Average percent BOLD signal change over the LOCC, LVOC, RIPS, RsIPS, and RfsMFG ROIs across set size for shape (blue) and color (orange) trials. Responses were significantly higher for color at set sizes 3 and 6. Error bars depict ± 1/2 SE.
Mentions: The remaining five clusters showed an increasing pattern across set size, with a decline at set size 6. Data from these clusters were analyzed together in a three-factor ANOVA with Set Size, Dimension, and Cluster as factors. There was a significant main effect of SS, F(5,380) = 4.48, p < 0.001, and a significant SS × Dimension interaction, F(5,380) = 2.40, p < 0.05. The interaction effect is shown in Figure 4. The BOLD response for the Color dimension rises more steeply and remains high across set sizes 3–6. By contrast, the BOLD response for the Shape dimension rises more gradually and falls off dramatically at set size 6. Post hoc tests determined that the BOLD response for the Color dimension was significantly greater than the Shape dimension at SS3 and SS6, p < 0.05. This is consistent with behavioral results that showed greater Max K for Color than for Shape.

Bottom Line: As expected, capacity was significantly lower for the shape dimension.Similarly, participants with a stronger BOLD response for color also showed a strong neural response for shape within the lateral occipital cortex, intraparietal sulcus (IPS), and superior IPS.Although there were robust individual differences in the behavioral and neural measures, we found little evidence of systematic brain-behavior correlations across feature dimensions.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Mathematics and Computational Sciences, University of Iowa, Iowa City IA, USA.

ABSTRACT
Visual working memory (VWM) is a key cognitive system that enables people to hold visual information in mind after a stimulus has been removed and compare past and present to detect changes that have occurred. VWM is severely capacity limited to around 3-4 items, although there are robust individual differences in this limit. Importantly, these individual differences are evident in neural measures of VWM capacity. Here, we capitalized on recent work showing that capacity is lower for more complex stimulus dimension. In particular, we asked whether individual differences in capacity remain consistent if capacity is shifted by a more demanding task, and, further, whether the correspondence between behavioral and neural measures holds across a shift in VWM capacity. Participants completed a change detection (CD) task with simple colors and complex shapes in an fMRI experiment. As expected, capacity was significantly lower for the shape dimension. Moreover, there were robust individual differences in behavioral estimates of VWM capacity across dimensions. Similarly, participants with a stronger BOLD response for color also showed a strong neural response for shape within the lateral occipital cortex, intraparietal sulcus (IPS), and superior IPS. Although there were robust individual differences in the behavioral and neural measures, we found little evidence of systematic brain-behavior correlations across feature dimensions. This suggests that behavioral and neural measures of capacity provide different views onto the processes that underlie VWM and CD. Recent theoretical approaches that attempt to bridge between behavioral and neural measures are well positioned to address these findings in future work.

No MeSH data available.