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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 across set size for each ROI that demonstrated a significant effect of Set Size. Error bars depict ± 1/2 SE.
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Figure 3: Average percent BOLD signal change across set size for each ROI that demonstrated a significant effect of Set Size. Error bars depict ± 1/2 SE.

Mentions: Figure 3 shows average percent signal change across the set size manipulation for each cluster. LTPJ was the only cluster to show a decline in the BOLD response across Set Size, F(5,95) = 2.71, p < 0.05, replicating findings reported by Todd and Marois (2005). Note that there were no significant differences in the LTPJ response across stimulus dimensions. Additionally, V3a showed a very gradual increase in the BOLD response across set size, F(5,95) = 2.68, p < 0.05. Once again, there were no significant differences in the V3a response across stimulus dimensions, although the BOLD response was generally higher for Shape than for Color [F(1,95) = 3.29, p = 0.085].


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 across set size for each ROI that demonstrated a significant effect of Set Size. Error bars depict ± 1/2 SE.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 3: Average percent BOLD signal change across set size for each ROI that demonstrated a significant effect of Set Size. Error bars depict ± 1/2 SE.
Mentions: Figure 3 shows average percent signal change across the set size manipulation for each cluster. LTPJ was the only cluster to show a decline in the BOLD response across Set Size, F(5,95) = 2.71, p < 0.05, replicating findings reported by Todd and Marois (2005). Note that there were no significant differences in the LTPJ response across stimulus dimensions. Additionally, V3a showed a very gradual increase in the BOLD response across set size, F(5,95) = 2.68, p < 0.05. Once again, there were no significant differences in the V3a response across stimulus dimensions, although the BOLD response was generally higher for Shape than for Color [F(1,95) = 3.29, p = 0.085].

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.