 To eliminate the confound, experimenters ensure that performance does not differ between conditions where consciousness is present and where it is not. Where this was controlled, widespread activation was not clearly observed (Lau &amp; Passingham 2006). Still, the absence of observed activity by an imaging technique does not imply the absence of actual activity for the activity might be beyond the limits of detection of that technique. Further, there is a general concern about the significance of null results given that neuroscience studies focused on prefrontal cortex are typically underpowered (for discussion, see Odegaard, Knight, &amp; Lau 2017).