test reliability
test reliability relates to brain function and cognitive performance. Peak Brain Institute explores how QEEG brain mapping and neurofeedback training connect to test reliability through evidence-based approaches. Explore our 2 research papers covering this topic.
Research Papers
Test–retest reliability of resting EEG spectra validates a statistical signature of persons
Objective When EEG is recorded in humans, the question arises whether the resting EEG remains stable. We compared the inter-individual variation in spectral observables to the intra-individual stability over more than a year. Methods We recorded resting EEG in 55 healthy adults with eyes closed. In 20 persons EEG was recorded in a second session with retest intervals 12–40 months. For electrodes AFz, Cz and Pz α peak frequency and α peak height were transformed into Z-scores. We compared the curve shape of power spectra by first aligning α peaks to 10Hz and then regressing spectra pairwise onto each other to calculate a t-value. The t-value and differences of Z-scores for all pairs of sessions were entered into a generalized linear model (GLM) where binary output represents the recognition probability. The results were cross-validated by out-of-sample testing. Results Of the 40 sessions, 35 were correctly matched. The shape of power spectra contributed most to recognition. Out of all 2960 pairwise comparisons 99.5% were correct, with sensitivity 88% and specificity 99.5%. Conclusions Our statistical apparatus allows to identify those spectral EEG observables which qualify as statistical signature of a person. Significance The effect of external factors on EEG observables can be contrasted against their normal variability over time.
View Full Paper →Exploring Hemispheric Differences in Infrared Brain Emissions
Background. Carmen (Toomim & Carmen, 1999) has shown that training to increase frontal lobe infrared emissions with neurofeedback techniques inhibits migraine pain, but nothing is known about the psychological correlates of the infrared signal. We assess if reading out loud would increase activation in the left hemisphere in comparison to the right. We also assessed test/retest reliability by repeating measures a week later. Methods. Measurements of infrared activity, while reading or not, were taken three times from the left, center, and right forehead of 24 persons who had signed Institutional Review Board approved consent forms. The order of reading and non-reading was varied systematically. Results. Significant differences in activation favoring the right rather than the left hemisphere were found, but only in those who read first. Both order-of-reading groups significantly declined in overall activity during the second session. Five of six Pearson correlations measuring test/retest reliabilities in the reading-first group and two of six in the reading-second group attained statistical significance. Only measurements taken at the left forehead site were reliable across all four conditions, which represent the combination of two orders and two types of stimulation. Conclusions. Test/retest correlations provide some support for the inference that the infrared measures reflect enduring traits, especially in the left hemisphere. Hemispheric difference data suggest that infrared emissions were sensitive to processes such as orientation, habituation and attention. There was no evidence of sensitivity to left hemisphere specialization for verbal processing.
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