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Coarse-to-fine construction for high-resolution representation in visual working memory.

Gao Z, Ding X, Yang T, Liang J, Shui R - PLoS ONE (2013)

Bottom Line: No CDA difference was found between two and four objects, even in an easy-comparison condition.Thus, Experiment 2 manipulated the memory array's exposure time under the easy-comparison condition and found a significant CDA difference at 100 ms while replicating Experiment 1's results at 500 ms.In Experiment 3, the 500-ms memory array was blurred to block the detailed information; this manipulation reestablished a significant CDA difference.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology and Behavioral Sciences, Zhejiang University, Hangzhou, China.

ABSTRACT

Background: This study explored whether the high-resolution representations created by visual working memory (VWM) are constructed in a coarse-to-fine or all-or-none manner. The coarse-to-fine hypothesis suggests that coarse information precedes detailed information in entering VWM and that its resolution increases along with the processing time of the memory array, whereas the all-or-none hypothesis claims that either both enter into VWM simultaneously, or neither does.

Methodology/principal findings: We tested the two hypotheses by asking participants to remember two or four complex objects. An ERP component, contralateral delay activity (CDA), was used as the neural marker. CDA is higher for four objects than for two objects when coarse information is primarily extracted; yet, this CDA difference vanishes when detailed information is encoded. Experiment 1 manipulated the comparison difficulty of the task under a 500-ms exposure time to determine a condition in which the detailed information was maintained. No CDA difference was found between two and four objects, even in an easy-comparison condition. Thus, Experiment 2 manipulated the memory array's exposure time under the easy-comparison condition and found a significant CDA difference at 100 ms while replicating Experiment 1's results at 500 ms. In Experiment 3, the 500-ms memory array was blurred to block the detailed information; this manipulation reestablished a significant CDA difference.

Conclusions/significance: These findings suggest that the creation of high-resolution representations in VWM is a coarse-to-fine process.

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Related in: MedlinePlus

The averaged CDA amplitudes for the four critical conditions in Experiment 2.*indicates the difference between the two conditions was significant. The CDA is a difference wave, constructed by subtracting the ipsilateral from the contralateral activity according to the cued hemifield. (Error bars denote standard error).
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pone-0057913-g005: The averaged CDA amplitudes for the four critical conditions in Experiment 2.*indicates the difference between the two conditions was significant. The CDA is a difference wave, constructed by subtracting the ipsilateral from the contralateral activity according to the cued hemifield. (Error bars denote standard error).

Mentions: Finally, CDA amplitudes were compared among the four critical conditions (see Fig. 5), among which the amplitude of four objects in the 100-ms condition was the highest. A one-way ANOVA revealed a significant main effect of Condition, F(3,39) = 18.88, p<.001. Post hoc contrasts showed that the CDA amplitude for four objects in the 100-ms condition was more negative than that in the other three conditions, ps <.025. There were no significant differences among the other three critical conditions, all ps >.5.


Coarse-to-fine construction for high-resolution representation in visual working memory.

Gao Z, Ding X, Yang T, Liang J, Shui R - PLoS ONE (2013)

The averaged CDA amplitudes for the four critical conditions in Experiment 2.*indicates the difference between the two conditions was significant. The CDA is a difference wave, constructed by subtracting the ipsilateral from the contralateral activity according to the cued hemifield. (Error bars denote standard error).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585254&req=5

pone-0057913-g005: The averaged CDA amplitudes for the four critical conditions in Experiment 2.*indicates the difference between the two conditions was significant. The CDA is a difference wave, constructed by subtracting the ipsilateral from the contralateral activity according to the cued hemifield. (Error bars denote standard error).
Mentions: Finally, CDA amplitudes were compared among the four critical conditions (see Fig. 5), among which the amplitude of four objects in the 100-ms condition was the highest. A one-way ANOVA revealed a significant main effect of Condition, F(3,39) = 18.88, p<.001. Post hoc contrasts showed that the CDA amplitude for four objects in the 100-ms condition was more negative than that in the other three conditions, ps <.025. There were no significant differences among the other three critical conditions, all ps >.5.

Bottom Line: No CDA difference was found between two and four objects, even in an easy-comparison condition.Thus, Experiment 2 manipulated the memory array's exposure time under the easy-comparison condition and found a significant CDA difference at 100 ms while replicating Experiment 1's results at 500 ms.In Experiment 3, the 500-ms memory array was blurred to block the detailed information; this manipulation reestablished a significant CDA difference.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology and Behavioral Sciences, Zhejiang University, Hangzhou, China.

ABSTRACT

Background: This study explored whether the high-resolution representations created by visual working memory (VWM) are constructed in a coarse-to-fine or all-or-none manner. The coarse-to-fine hypothesis suggests that coarse information precedes detailed information in entering VWM and that its resolution increases along with the processing time of the memory array, whereas the all-or-none hypothesis claims that either both enter into VWM simultaneously, or neither does.

Methodology/principal findings: We tested the two hypotheses by asking participants to remember two or four complex objects. An ERP component, contralateral delay activity (CDA), was used as the neural marker. CDA is higher for four objects than for two objects when coarse information is primarily extracted; yet, this CDA difference vanishes when detailed information is encoded. Experiment 1 manipulated the comparison difficulty of the task under a 500-ms exposure time to determine a condition in which the detailed information was maintained. No CDA difference was found between two and four objects, even in an easy-comparison condition. Thus, Experiment 2 manipulated the memory array's exposure time under the easy-comparison condition and found a significant CDA difference at 100 ms while replicating Experiment 1's results at 500 ms. In Experiment 3, the 500-ms memory array was blurred to block the detailed information; this manipulation reestablished a significant CDA difference.

Conclusions/significance: These findings suggest that the creation of high-resolution representations in VWM is a coarse-to-fine process.

Show MeSH
Related in: MedlinePlus