FIGURE 13.3. Classical interaction design: 2 × 2 factorial design manipulating presence versus absence of sensory inputs.

FIGURE 13.3

Classical interaction design: 2 × 2 factorial design manipulating presence versus absence of sensory inputs. (a) Experimental design: 2 × 2 factorial design with the factors (1) auditory: present versus absent; (2) visual: present versus absent. Example stimuli are presented as visual images and corresponding sound spectrograms. (b–d) Data analysis and interpretation. Three activation profiles are illustrated. (b) Superadditive interaction as indexed by a positive MSI effect. (c) Subadditive interaction as indexed by a negative interaction term in context of audiovisual enhancement. (d) Subadditive interaction as indexed by a negative interaction term in context of audiovisual suppression. Please note that subadditive (yet not suppressive) interactions can also result from nonlinearities in BOLD response. Bar graphs represent effect for auditory (black), visual (darker gray), and audiovisual (lighter gray) stimuli, and “multisensory” (gray) effect as defined by audiovisual interaction (AV + Fix) – (A + V). To facilitate understanding, two additional bars are inserted indicating sums that enter into interaction, i.e., AV + Fix and A + V.

From: Chapter 13, Characterization of Multisensory Integration with fMRI

Cover of The Neural Bases of Multisensory Processes
The Neural Bases of Multisensory Processes.
Murray MM, Wallace MT, editors.
Boca Raton (FL): CRC Press; 2012.
Copyright © 2012 by Taylor & Francis Group, LLC.

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