The comparative memory of a model particle suspension

Under repeated oscillatory shear, a non-Brownian suspension can form a memory of the strain amplitude of shearing, and even of multiple amplitudes applied over many cycles. We study a kinematic model of such a suspension, and we focus on how this memory functions to compare two amplitudes applied at different times, so that the system's response indicates which one is larger. We study the effects of the sequence of strains and key factors such as noise. We explore analogies to functional memories in the brain, inspired by neuroscience experiments that study the properties of working memory in humans and rats. Mimicking those behavioral experiments, many pairs of strain values are used to drive the model particle suspension, and we characterize its performance as a comparator and its biases. Results give us a robust way of searching for a memory in the system and show promising evidence for a comparative memory. We can see how noise affects the timescales of the memory and how the system behaves under different sequences of strains.