The Color Phi phenomenon: not so special, after all?
We show how anomalous time reversal of stimuli and their associated responses can exist in very small connectionist models. The networks these models exist of, are built using a dynamical toy model neuron, and adhere to a minimal set of biologically plausible properties. The appearance of a “ghost” response, temporally and spatially located in between responses caused by actual stimuli, as in the Phi phenomenon, is demonstrated in a similar small network, where it is caused by priming and long-distance feedforward paths. We then demonstrate that the Color Phi phenomenon can be present in an Echo State Network, a dynamical recurrent neural network, markedly without explicitly training for the presence of the effect. Our results suggest that similar illusions are likely to be obtainable for any system, artificial or biological in nature, with minimal neuron-like properties, and are thus merely artifacts of the inherent dynamical and nonlinear behavior and of suchsystems.