Pritchard W S, Warm J S
J Exp Psychol Gen. 1983 Jun;112(2):145-75. doi: 10.1037//0096-3445.112.2.145.
Leading explanations of the subjective contour illusion can be classified as being either "bottom-up" or "top-down." Bottom-up explanations assert that peripheral, physiological mechanisms often associated with the perception of real contours also account for subjective contour (SC) perception. In contrast, top-down explanations posit a more central locus of SC perception and are formulated on a molar, psychological level. A major aspect of bottom-up perceptual processing is that it is largely automatic. On the other hand, top-down processing implies a greater role for selective attention. In an effort to distinguish between bottom-up and top-down accounts of SC perception, the present investigation used a dual-task paradigm to test the relative attentional demands of real contour perception versus SC perception. In the primary task, subjects made speeded same-different discriminations of either paired SC forms or their real contour analogues. Half the subjects performed this primary task in conjunction with a six-digit short-term memory load secondary task. If subjective forms indeed impose a greater limited-capacity processing load than real forms, then the need to share processing capacity with a secondary task was expected to produce a greater increment in reaction time (RT) for subjective relative to real forms. The results indicated that the expected enhanced RT increment for subjective relative to real forms with the addition of a concurrent memory load was limited to same trials. This result implies that the nature of response indicators must be considered in assessing capacity requirements with the sort of dual-task paradigm used in the present investigation. Nevertheless, the fact that the increment in same RT with the addition of a concurrent memory load was greater for subjective relative to real forms accords with expectations derived from the notion that the perception of SCs is more attention demanding than that of real contours. If the interpretation of the present study is correct, then a comprehensive theory of SC perception will most likely be formulated within the top-down perspective of conceptually driven visual information processing.
对主观轮廓错觉的主流解释可分为“自下而上”或“自上而下”两类。自下而上的解释认为，通常与真实轮廓感知相关的外周生理机制也能解释主观轮廓（SC）感知。相比之下，自上而下的解释则假定SC感知的中枢位置更为重要，并在整体的心理层面上进行阐述。自下而上的感知处理的一个主要方面是它在很大程度上是自动的。另一方面，自上而下的处理意味着选择性注意发挥更大的作用。为了区分对SC感知的自下而上和自上而下的解释，本研究采用了双任务范式来测试真实轮廓感知与SC感知的相对注意力需求。在主要任务中，受试者对成对的SC形式或其真实轮廓类似物进行快速的异同辨别。一半的受试者在执行这个主要任务的同时还要完成一个六位数的短期记忆负荷的次要任务。如果主观形式确实比真实形式施加了更大的有限容量处理负荷，那么与次要任务共享处理能力的需求预计会使主观形式相对于真实形式的反应时间（RT）有更大的增加。结果表明，在添加并发记忆负荷的情况下，主观形式相对于真实形式预期的RT增加增强仅限于相同试验。这一结果意味着，在用本研究中使用的双任务范式评估能力需求时，必须考虑反应指标的性质。然而，添加并发记忆负荷时，主观形式相对于真实形式在相同RT上的增加更大，这一事实符合从SC感知比真实轮廓感知更需要注意力这一观点得出的预期。如果本研究的解释是正确的，那么SC感知的综合理论很可能会在概念驱动的视觉信息处理的自上而下视角内形成。
