Analog VLSI circuits for covert attentional shifts

In this paper we present analog very large-scale integrated (aVLSI) circuits that facilitate the selection process for initiating and mediating attentive visual processing. We demonstrate the performance of these circuits within a system that implements covert attentional shifts based on an input array that represents saliency across the visual field. The selection process, which enables the transition from preattentive to attentive processing, uses knowledge of previous selections and appropriate duration of selections to perform its task. The circuitry uses local feedback to create a hysteretic effect in the switching from one location of attention to the next. We also include an inhibition-of-return mechanism to facilitate shifting the location of attention even when the input array remains constant. We present test data from a one-dimensional version of the system.