Multisensory interactions in early evoked brain activity follow the principle of inverse effectiveness

► In animals, largest multisensory interactions occur when inputs evoke low responses. ► We examine this principle of inverse effectiveness (IE) in humans. ► Multisensory interactions (MI) in behavior were strongest for low intensity stimuli. ► Low intensity audiovisual stimuli show strongest MI in early evoked brain activity. ► The strength of MI in early evoked potentials in humans follows the principle of IE.