Petersik J T
Percept Mot Skills. 1978 Dec;47(3 Pt 1):683-98. doi: 10.2466/pms.1978.47.3.683.
Two studies examined the role played by transient and sustained visual mechanisms in the determination of similarity judgments produced in response to pairs of geometrical stimuli. In two experiments, subjects were trained to attend to two dimensions of a set of stimuli and to assign similarity ratings with respect to those two dimensions only. An INDSCAL multidimensional scaling analysis of the subsequent similarity ratings showed that subjects emphasized global blob, or low spatial frequency-dependent, dimensions of the stimuli when they were presented for brief durations (20 msec.), irrespective of the dimensions to which the subjects and had been trained to attend. This finding suggested that low spatial frequency selective transient mechanisms dominated the perceptual processes which underlie the similarity judgments. When the stimulus duration was raised to 50 msec. so that sustained mechanisms could also make a signficicant contribution to the perceptual processes underlying the similarity judgments, subjects emphasized only those dimensions on which they had been trained. The implications of the present findings for the concepts of selective attention and automatic activation were discussed.
两项研究考察了瞬态和持续视觉机制在确定对几何刺激对做出反应时产生的相似性判断中所起的作用。在两项实验中，受试者被训练关注一组刺激的两个维度，并仅根据这两个维度给出相似性评分。对随后的相似性评分进行的INDSCAL多维尺度分析表明，当刺激呈现短暂持续时间（20毫秒）时，受试者强调刺激的整体斑点或低空间频率相关维度，而不管受试者被训练关注的维度如何。这一发现表明，低空间频率选择性瞬态机制主导了相似性判断背后的感知过程。当刺激持续时间增加到50毫秒，以便持续机制也能对相似性判断背后的感知过程做出显著贡献时，受试者只强调他们接受过训练的那些维度。讨论了本研究结果对选择性注意和自动激活概念的影响。
