Influence of imaged pictures and sounds on detection of visual and auditory signals.

The present study compared sensitivity for auditory and visual signals in a simple detection task and in a related task in which ,9 was also imaging mental pictures and sounds. Sensitivity (rf') was reduced during imagery; within the imaging conditions, it was smaller when image and signal were both auditory or both visual than for cross-modal conditions and smaller with unfamiliar than familiar images. Likelihood ratio (Lx) was also smaller in the isomodal imaging conditions, as there were more visual false alarms during visual imagery and more auditory false alarms during auditory imagery. The data are not consistent with the assumption that d' is lower during imagery due to distraction; they do not entirely fit a channel competition model, but suggest that imagery functions as an internal signal which is confused with the external signal.