RSVP任务下双刺激重复的优势与劣势

本研究探讨重复知盲发生在知觉阶段还是在记忆阶段。采用快速视觉系列呈现(rapid serial visual representation, 简称RSVP)任务, 让被试即时回忆80个词表中呈现的词。操作了词表中目标词的重复数, 分为无重复、单刺激重复(重复一对)和双刺激重复(重复两对)三种, 和目标词的情绪效价, 分为中性词和情绪词两种。结果发现, 对目标词回忆的正确率是：当目标词和非目标词都是中性词汇, 即二者的情绪效价强度相当时(实验1), 在无重复条件与双刺激重复条件下无差异, 二者均大于单刺激重复条件; 当目标词是消极词汇, 非目标词是中性词汇, 即目标刺激的情绪效价强度大于非目标刺激时(实验2), 无重复条件与单刺激重复条件无差异, 二者均大于双刺激重复条件。结果表明：(1)RSVP 任务下词表中有双刺激重复时, 如果刺激的效价强度相当, 出现重复优势; 如果目标刺激的效价强度高于非目标刺激, 出现重复劣势; (2)人们会主动分配更多的注意资源给效价高的刺激, 重复知盲产生在记忆阶段, 支持注意资源分配最优化假设。

Advantageous and Disadvantageous Repetition of Doubly Repeated Stimuli in RSVP Paradigm

To recognize or report the second occurrence of a target in RSVP paradigm is challenging, a phenomenon known as Repetition Blindness (RB; Kanwisher, 1987). Some scholars argue that RB is due to an encoding failure of a repeated stimulus (e.g., Kanwisher, 1987, 1991; Kanwisher & Potter, 1989, 1990), while others believe it is caused by a retrieval failure (e.g., Armstrong & Mewhort, 1995; Fagot & Pashler, 1995; Masson, 2004; Whittlesea & Masson, 2005). Morris, Still and Caldwell-Harris (2009) proposed the Competition Hypothesis to further explain RB with inter-item competition. However, under the time press, people may allocate attention resources according to the task to get the best recall performance. In the RSVP paradigm, to serve the purpose of detecting more distinctive stimuli, repeated stimuli receive less attention resource than the non-repeated stimuli during the perceptual phase. Consequently, repeated items become difficult to report during the retrieval phase. Recently, Leng, Tan, Zeng, Cheng, and Lu (2012) illustrated these views in their Optimization Allocation of Attention Resources Hypothesis. The present study aimed to further examine the mechanism of RB through a new method. The typical RSVP paradigm includes one pair of repeated item (single repetition, C1 and C1’).In our research, two pairs of repeated items (double repetition, C1 and C1’, and C2 and C2’) were created. A within-subject design with one variable was used in all three experiments, repetition of words with three levels (non-repeated, one pair of word repeated, and two pairs of words repeated). The dependent variable was the accuracy rate for reporting targets. If RB occurs in a single repetition RSVP and it occurs at the perceptual phase, then the effect of RB from the second repeated stimulus (C2’) should not occur in a double repetition RSVP because the first repeated stimulus (C2) can not be recognized in the RSVP streams. If RB occurs at the retrieval phase in a single repetition RSVP, then the effect of RB from the second repeated stimulus should occur in a double repetition RSVP because the first repeated stimulus can be recognized in the RSVP displays. The second pairs repeated stimuli C2 and C2’ as well as an item between them construct a single repetition RSVP, in which the RB from C2’ should occur. In Experiment 1, both targets and non-targets were neutral words; while in Experiments 2a and 2b, targets were emotional words and non-targets were neutral words. Experiment 1 found that the accuracy rate for targets in the singly repeated but not in the doubly repeated condition differed from accuracy rate in the non-repeated condition. However, in Experiments 2a and 2b, the accuracy rate for targets in the doubly repeated condition but not in the singly repeated condition differed from the accuracy rate in the non-repeated condition. The results indicated: (1) The methodological merits of the repetitiveness of doubly repeated stimuli in a RSVP paradigm depended on the value intensity of targets and non-targets. When the intensity between them was equivalent, the second repeated targets showed advantage. When the intensity from the targets was stronger relative to the non-targets, the second repeated targets showed disadvantage. (2) People can allocate more attention resources to the stimui with higher intensity. RB occurs at the retrieval phase, not at the perception phase. The Optimization Allocation of Attention Resources Hypothesis can reasonably explain the effect of RB.