Schematic representation of the study's factorial design and presentation of experimental stimuli and tasks.

<p>The four experimental tasks are presented in each quadrant. Each task is characterized by a sensory modality (visual or auditory) and by a level of cortical processing engaged during task completion (low- or mid-level). <b>A.</b> Luminance-contrast (LC) discrimination: gratings were presented for 753 ms each and separated by an inter-stimulus interval of 271 ms, during which a noise mask was presented to minimize spatial after effects. <b>B.</b> Pitch discrimination: pure tones were presented for 200 ms each and separated by an inter-stimulus interval of 212 ms. <b>C.</b> Block design completion: examples of minimum and maximum perceptual cohesiveness (PC) models. <b>D.</b> Melody discrimination: examples of a standard melody compared to contour modified and contour preserved conditions. Red arrows represent contour direction. Lines represent relationships of interest in the current study. Full lines: unimodal relationships, between levels of processing; Dotted lines: plurimodal relationships, within levels of processing.