Limits...
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.


Scatterplots showing correlations between behavioral measures across participants.(A) Scatterplot showing Color Max K and Shape Max K values across participants. (B) Scatterplot of relationship between Shape Max K and linear coefficient of fits of Shape K functions for each individual across set sizes. (C) Scatterplot of relationship between Color Max K and quadratic coefficients of fits of Color K functions for each individual across set size. (D) Scatterplot showing linear versus quadratic coefficients for quadratic fits of Color K functions across set size.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4835449&req=5

Figure 2: Scatterplots showing correlations between behavioral measures across participants.(A) Scatterplot showing Color Max K and Shape Max K values across participants. (B) Scatterplot of relationship between Shape Max K and linear coefficient of fits of Shape K functions for each individual across set sizes. (C) Scatterplot of relationship between Color Max K and quadratic coefficients of fits of Color K functions for each individual across set size. (D) Scatterplot showing linear versus quadratic coefficients for quadratic fits of Color K functions across set size.

Mentions: The other key result from Figure 1: participants showed clear individual differences. To examine whether these individual differences were consistent across dimensions, we correlated the Max K values across dimensions. There was a significant correlation, r = 0.64, p < 0.005, indicating that participants with a high capacity for colors generally also had a high capacity for shapes (see Figure 2A).


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)

Scatterplots showing correlations between behavioral measures across participants.(A) Scatterplot showing Color Max K and Shape Max K values across participants. (B) Scatterplot of relationship between Shape Max K and linear coefficient of fits of Shape K functions for each individual across set sizes. (C) Scatterplot of relationship between Color Max K and quadratic coefficients of fits of Color K functions for each individual across set size. (D) Scatterplot showing linear versus quadratic coefficients for quadratic fits of Color K functions across set size.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835449&req=5

Figure 2: Scatterplots showing correlations between behavioral measures across participants.(A) Scatterplot showing Color Max K and Shape Max K values across participants. (B) Scatterplot of relationship between Shape Max K and linear coefficient of fits of Shape K functions for each individual across set sizes. (C) Scatterplot of relationship between Color Max K and quadratic coefficients of fits of Color K functions for each individual across set size. (D) Scatterplot showing linear versus quadratic coefficients for quadratic fits of Color K functions across set size.
Mentions: The other key result from Figure 1: participants showed clear individual differences. To examine whether these individual differences were consistent across dimensions, we correlated the Max K values across dimensions. There was a significant correlation, r = 0.64, p < 0.005, indicating that participants with a high capacity for colors generally also had a high capacity for shapes (see Figure 2A).

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.