A fixed class covariance test failed in 14 iEEG patients and six fMRI adults

We tested whether image classes have different covariances across brain sites after class means, equal-loading common signals and independent site variances are removed. Separate public studies supplied human iEEG and fMRI. Three patients and two MRI adults supplied development. A local code lock preceded tests in 14 other patients and six other adults. The assay uses products from four distinct images and a separate scale panel. Mean contrasts were 0.009871 and 0.001755. Pointwise 95% person Student limits were [-0.025237, +0.044979] and [-0.000917, +0.004427]. Scores were positive in 8/14 and 5/6 people. The fixed shared mean-and-majority rule failed, p=0.39526367. No positive cross-modal neural claim was confirmed. An exploratory audit found larger ordinary squared-covariance values in 14/14 and 6/6 people. The tool removes finite-sample square bias under independent-image assumptions. An exact model shows that class-dependent correlated error can still give a positive target with equal neural covariances. Source selection, clinical sampling, different cohorts, image groups and signal filters limit scope. This is a new endpoint in reused studies. The package has code, source pins and terms, all results, figures, local plans, numerical checks and repeat instructions. Original neural arrays remain external.

human neuroscience · intracranial EEG · fMRI · visual objects · covariance · U-statistic · negative result · measurement error