Many experiments require counterbalancing sequences of trials. For example, I’m currently running an experiment on serial dependence1. In my experiment, participants report the orientation of a grating2 stimulus on each trial. The serial dependence effect is how their responses on one trial depend on either the orientation of the previous trial or their response on that trial. To tease apart the effects of prior stimuli from prior responses, I’m manipulating the visual contrast of the gratings ( Michelson contrast ).
Functional magnetic resonance imaging records brain activity with spatially distinct voxels, but this segmentation will be misaligned with a brain’s meaningful boundaries. The segmentation results in some voxels recording activity from different types of tissue – types that are both neural an non-neural – but even voxels that exclusively sample gray matter can span functionally distinct cortex. For example, a 3T scanner allows voxels in the range of 1.