Senslploration. As narrated in this video by Professor Charles Spence it is a springboard to multimodal perception. The superadditive maximizes congruence whereas the subadditive induces incongruence.
From an art standpoint, multimodal perception is usually celebrated in the form of synesthesia which literally means “union of the senses”. Some believe synesthesia is common in early childhood, and as the senses become more differentiated the world gradually loses its rich perceptual overtones in which something as basic as numbers are linked with specific colors, and geometric patterns are bathed in a palette of particular colors.
Synesthesia is reported to occur in only 4% of the population among adults. In rare cases it has been reported to occur following stroke or other forms of acquired brain injury (ABI). But such superadditivity is rare in ABI, and altered neural pathways much more frequently result in subadditivity. The subadditive results in noise, fragmentation, incongruity, and even incoherence at times.
Mention the terms “sensory overload” and most people conceive of it as too much auditory input. Kids covering their ears because sounds are too numerous or too loud. Yet migraineurs are familiar with the need to de-tune visual input, sometimes needing to retreat into darkness to limit visual input. This is part of the continuum of Professor Spence would term “subadditive multimodal overstimulation”. One way (a suggestion from the wrongplanet.net forum) for an individual to handle visual sensory overload might be a self-tuning filter gizmo. Those who deal with syntonics apply particular color, perhaps tapping into a quasi-synesthetic therapy. Various lenses or prisms may also tap into synesthetic pathways.
We increasingly encounter patients with subadditive multisensory overload developmentally (as in Autism Spectrum Disorder), or as part of their ABI/PTVS (Post-Trauma Vision Syndrome) experiences. The multimodal nature of PTVS makes it particularly challenging, and successful vision therapy finds ways to reduce if not eliminate subadditivity. We help put back together parts of the multisensory environment that has become fragmented or incongruous.
This requires initially that we pay particular attention to the therapy environment. To be as conscious of the effects of ambient sound as to the effects of ambient light. And as we lay out activities or procedures, to be very mindful of the complexity. We begin by deconstructing tasks into very basic steps and, as if building an orchestra piece by piece, be mindful of the visual spatial array of the players in addition to their integrative sounds.