Voluntary Generation of Hyperchaotic Visuo-Motor Patterns

Unpredictable escape behaviour is an integral part of the repertoire of many prey species. Many social species, including humans, also employ unpredictability to enhance their chances of success in social interactions with conspecifics. However, it is unclear what mechanisms provide the behavioural and neural bases of this unpredictability, which might result either from randomness or from chaotic dynamics. A novel paradigm described here demonstrates that unpredictable behaviour generated voluntarily in a simple visuomotor task represents high dimensional chaos, or hyperchaos, but not randomness. The exponential decay of predictability was also shown to be longer in older adults. As chaos has been observed among cortical neurons, this provides a plausible neural basis for hyperchaos. These results thus provide evidence that voluntary unpredictable behaviour can result from neural hyperchaos. This work has implications for the study of autism, aftereffects of concussions, early dementia, and the concept of free will.