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Table 3 List of issues that need consideration when designing bioelectromagnetic studies on cognitive performance measures - Impact, importance and recommendations.

From: Cognitive Performance Measures in Bioelectromagnetic Research - Critical Evaluation and Recommendations

Issue Impact Importance Recommendation(s)
Task type Detection of effect High Use tasks which previously revealed effects and/or address the same cognitive variable (i.e. 'selective attention', 'working memory'); select task related to exposed brain region
Input and response modalities Comparability between studies Medium Use modalities applied in tasks that previously revealed effects
Learning effects Error variance and type II error Medium Include practice sessions; apply conditions in a crossover design; use parallel test forms or random or pseudo-random sequences
Task specificity Detection of effect High Select task related to exposed brain region; if appropriate correct for multiple comparisonsa
Timing of tasks, task order and task duration Development of effect; comparability between studies; alertness and motivation High Apply tasks with varying difficulty repeatedly in the same order; chose task difficulty and duration wisely to obviate fatigue and/or motivational loss
Study population and sample size Effect size and significance; external validity High Run power analysis to get an indication of sufficiently large sample size; use homogeneous group for small sample sizes; apply proper matching procedures for two or more study groups; characterize study population
Handedness Comparability between studies; homogeneity of study group(s) Low to Mediumb Include either right or left handers
Inclusion criteria and exclusion criteria Detection of effect; comparability between studies; homogeneity of study group(s) Medium to High Define clear criteria prior and within a study according to the subject of investigation
Confounding factors Error variance and type II error High Control for confounding factors as much as possible experimentally; apply randomization; check compliance of participants to predefined requirements
Experimental design and blinding Detection of effect High Use within-subject, cross-over design if possible; double blinding is mandatory
Exposure conditions Detection of effect; effect size and significance; interpretation High Ensure standardized reproducible exposure conditions; document setup and technical specifications (including signal characteristics); determine exposed brain areas
Field conditions and dosimetry Interpretation High Use field intensities close to exposure limits; provide clear definition of field conditions; dosimetry and sham condition (no field) mandatory
Exposure duration and carryover effects Interpretation; detection of effect High Allow for sufficient exposure duration; consider potential carryover effects in a crossover design; allow for sufficient time interval ('washout period') between conditions
  1. It must be noted that Table 3 contains generalized recommendations only and reflects the main issues which should be considered when designing a new study investigating RF EMF effects on mental processing; however, due to the complexity of each issue the recommendations may not fit all purposes by default. For a more elaborate discussion of each issue and the corresponding implications the reader is referred to the respective chapter of the review.
  2. a A substantial sample size is needed to adequately perform such a correction; b of high importance when assessing motor reaction times with a cognitive task.