Previous neurophysiological and imaging research has implicated a widely distributed array of brain regions in perceptual decision-making. However, identifying primary decision-forming regions as distinct from sensory encoding and motor activity that correlate them has been challenging, in significant part due to uncertainty in the identifying criteria applied. Here we applied the paradigms and criteria previously used to identify an EEG signature of motor-independent evidence accumulation (O'Connell, Dockree, & Kelly 2012), in an fMRI study. It involved a mental counting task assessing visual target detection without external responses, followed by visual and auditory tasks requiring motor responses. The visual and auditory tasks involved adjustments in contrast and volume, respectively, bracketed by variable inter-trial intervals, with EEG and fMRI data collected across separate sessions. We analysed fMRI data from 28 participants collected so far using SPM12 (Penny et al. 2011) to identify decision-related regions independent of sensory input and motor execution. The preliminary analysis highlighted common regions across tasks, including frontal and parietal regions implicated in prior decision-making research and consistent with a previous dataset with 13 participants. EEG analysis unveiled average centroparietal positivity profiles, consistent with previous research, enabling EEG source reconstruction to explore decision-making's temporal dynamics. Preliminary findings suggest distinct task networks with overlaps indicating a supramodal signal, independent of motor functions and sensory modality. Future work will focus on fMRI-guided EEG source reconstruction, aiming to uncover nuances of decision-related source activity with unparalleled temporal and spatial precision.