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Published on: July 16, 2015
Contralateral delay activity as a marker of visual working memory capacity: A multi-site registered replication.
Dawid Strzelczyk1, Peter E Clayson2, Heida Maria Sigurdardottir3
1Methods of Plasticity Research, Department of Psychology, University of Zurich, Zurich, Switzerland; Neuroscience Center Zurich (ZNZ), University of Zurich and ETH Zurich, Zurich, Switzerland.
Summary
The contralateral delay activity (CDA) reliably tracks visual working memory (VWM) capacity. However, large-scale replication revealed that correlations between CDA and VWM may be overestimated due to selective reporting.
Area of Science:
- Cognitive Neuroscience
- Electrophysiology
- Psychology
Background:
- The contralateral delay activity (CDA) is a key electrophysiological marker for visual working memory (VWM).
- Concerns exist regarding the sufficiency of typical sample sizes in detecting CDA set size effects and brain-behavior correlations.
- The #EEGManyLabs initiative aims to address replicability in electrophysiological research.
Purpose of the Study:
- To rigorously test the replicability of findings by Vogel and Machizawa (2004) concerning CDA and VWM capacity.
- To investigate the robustness of the correlation between CDA amplitude changes and individual VWM capacity using a large, multi-site sample.
- To assess potential overestimation of effect sizes and publication bias in previous CDA research.
Main Methods:
- A multi-site replication study involving 304 participants across 10 laboratories.
- Utilized a preregistered analysis plan to ensure transparency and rigor.
- Employed electroencephalography (EEG) to measure CDA and cognitive tasks to assess VWM capacity.
Main Results:
- Replicated the contralateral-ipsilateral asymmetry and observed increases in CDA amplitude with increasing set sizes (2 to 4, 2 to 6).
- The hypothesized positive correlation between CDA amplitude increase and VWM capacity was not replicated (meta-analytic r = .15 vs. original r = .78).
- Funnel-plot diagnostics suggested small-study inflation and publication bias in the existing literature.
Conclusions:
- Reports of strong correlations between CDA amplitude and VWM capacity may be overestimated, potentially due to selective reporting.
- The study underscores the importance of large-scale, preregistered, and transparent research for accurately characterizing brain-behavior associations.
- Open science practices are crucial for robustly assessing individual-difference associations in psychophysiology.
