The effects of space on Multisensory Integration.
Summary
The integration of sensory signals from different modalities is sensitive not only to the spatial
and temporal relationship of these sensory signals, but also to their intensity. It is said that low
intensity unimodal stimuli elicit a larger integration response when presented together than high
intensity unimodal stimuli do. This phenomenon is also known as inverse effectiveness.
Although the mechanics of inverse effectiveness in two-dimensional space are well established, for three-
dimensional space this is not so much the case.
In the present study, stimuli of different intensities were presented in near and far space in
order to elicit an inverse effectiveness effect. This way a possible interaction between depth and
inverse effectiveness could be examined. Integration was present in both near and far space, and
stimuli of high and low intensity behaved according to the inverse effectiveness rule in both near and far space.
Although the difference in integration between high and low intensity stimuli did not differ
between near and far space, an interaction effect of space with inverse effectiveness was found
when comparing the near space high intensity condition with the far space low intensity condition.
This outcome, together with a marginally significant main effect of distance on integration, led us
to the conclusion that space on its own is too weak of a factor to significantly influence integration,
but in conjunction with inverse effectiveness has an effect on multisensory integration.