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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

Example of a change trial in the left hemifield in Experiment 1.
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pone-0057913-g002: Example of a change trial in the left hemifield in Experiment 1.

Mentions: The participants were seated in an electrically shielded and sound-attenuated recording chamber at a distance of 70 cm from a 17-inch monitor. The stimulus arrays were presented within two 4°×7.3° rectangular areas, centered 4° to the left and right of a central fixation cross against a gray background. The memory array were presented in the two rectangle areas, each having an equal number of 2 or 4 shapes, yet shapes and their corresponding locations in each area were selected independently (see the memory array in Fig. 2). Each time participants remembered the 2 or 4 shapes in a cued area (see details below). When the complex shapes were adopted as materials, items located within the same hemifield of the memory array were selected from five distinct categories. The positions of the memory items were randomly selected in each trial with the constraint that the center-to-center angle between items be at least 2.5°.


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)

Example of a change trial in the left hemifield in Experiment 1.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0057913-g002: Example of a change trial in the left hemifield in Experiment 1.
Mentions: The participants were seated in an electrically shielded and sound-attenuated recording chamber at a distance of 70 cm from a 17-inch monitor. The stimulus arrays were presented within two 4°×7.3° rectangular areas, centered 4° to the left and right of a central fixation cross against a gray background. The memory array were presented in the two rectangle areas, each having an equal number of 2 or 4 shapes, yet shapes and their corresponding locations in each area were selected independently (see the memory array in Fig. 2). Each time participants remembered the 2 or 4 shapes in a cued area (see details below). When the complex shapes were adopted as materials, items located within the same hemifield of the memory array were selected from five distinct categories. The positions of the memory items were randomly selected in each trial with the constraint that the center-to-center angle between items be at least 2.5°.

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