Focal Attention and Figural Synthesis
This chapter introduces the constructive approach by applying it to several minor issues which lie on the fringes of the pattern-recognition problem. The notion of focal attention can be conveniently approached by way of a fundamental dilemma, faced by all theories based on spatially parallel processing. The term "focal attention" is taken from Schachtel, a psychoanalyst who has tried to account for the growing child's increasing interest in and understanding of the real world without giving up the traditional analytic concern with affects and drives. The notion of figural synthesis suggests one speculative possibility. What seems familiar is not the stimulus object, after all, but the perceived object. Schemes for mechanical letter-recognition, including Selfridge's, have generally presented letters to the machine one at a time. Since the processes of focal attention cannot operate on the whole visual field simultaneously, they can come into play only after preliminary operations have already segregated the figural units involved.