Temporal patterns of human behaviour:
Are there signs of deterministic 1/f scaling ?

R.M. Dünki, E. Keller, P.F. Meier & B. Ambühl, PHYSICA A 276:596 - 609 (2000)

Keywords
Generic Intermittency Model, 1/f Scaling, Risk-Assessment, Schizophrenia

Temporal patterns apparently exhibiting scaling properties may originate either from fractal stochastic processes or from causal (i.e. deterministic) dynamics. In general, the distinction between the possible two origins remains a non-trivial task. This holds especially for the interpretation of properties derived from temporal patterns of various types of human behaviour, which were reported repeatedly.
We propose here a computational scheme based on a generic intermittency model to test predictability (thus determinisim) of a part of a time series with knowledge gathered from another part. The method is applied onto psychodynamic time series related to turns from non-psychosis to psychosis. A nonrandom correlation (r = 0.76) between prediction and real outcome is found. Our scheme thus provides a particular kind of fractal risk-assessment for this possibly deterministic process.
We briefly discuss possible implications of this findings to evaluate the risk to undergo a state transition, in our case a patients risk to enter a next psychotic state. We further point to some problems concerning data sample pecularities and equivalence between data and model setup.