  Could simple organisms such as slime mould approximate LI without recourse to
neural tissue? We describe a model whereby LI can emerge without explicit
inhibitory wiring, using only bulk transport effects. We use a multi-agent
model of slime mould to reproduce the char- acteristic edge contrast
amplification effects of LI using excitation via attractant based stimuli. We
also explore a counterpart behaviour, Lateral Activation (where stimulated
regions are inhibited and lateral regions are excited), using simulated
exposure to light irradiation. In both cases restoration of baseline activity
occurs when the stimuli are removed. In addition to the enhancement of local
edge contrast the long-term change in population density distribution
corresponds to a collective response to the global brightness of 2D image
stimuli, including the scalloped inten- sity profile of the Chevreul staircase
and the perceived difference of two identically bright patches in the
Simultaneous Brightness Contrast (SBC) effect. This simple
modelapproximatesLIcontrastenhancementphenomenaandglobalbrightnessper- ception
in collective unorganised systems without fixed neural architectures. This may
encourage further research into unorganised analogues of neural processes in
simple organisms and suggests novel mechanisms to generate collective
perception of contrast and brightness in distributed computing and robotic
devices.
