ABSTRACT
BACKGROUND:Researches on attentional blink (AB) emphasized the importance of the distractors directly following targets and that of the leading distractors in rapid serial visual presentation (RSVP) streams in the production of the AB,but little has been mentioned about the subsequent distractors after the second target (except the one in direct succession to it).OBJECTIVE: To investigate the effect of subsequent distractors in RSVP stream on AB after the second target (T2).DESIGN: A randomized and controlled study.SETTING: Laboratory of Cognitive Science, South-central University for Nationalities.PARTICIPANTS: Twenty-five undergraduates aging 18-21 years with the mean age of 19 years were selected from South-central University for Nationalities. All undergraduates participated in the experiment did not have nervous mental diseases but had normal sight or corrected visual acuity; meanwhile, all of them provided the confirmed consent. The subjects were divided into experimental group (n =14) and control group (n =11). There were no significant differences between the two groups in age and sex (P ＞ 0.05).METHODS: The experiment was carried out in the Laboratory of Cognitive Science, South-central University for Nationalities from January to April 2007. ① Experimental intervention: The stimuli were RSVP streams consisted of digit distractors and two letter targets (T1 and T2). ② Experimental grouping: The experimental group participated in the omitted condition and the control group participated in the preserved condition. ③ Experimental analysis: One-way ANOVA was used to evaluate the data for statistically significant difference in the same group, and t test was used to compare data between two groups.MAIN OUTCOME MEASURES: Report accuracy of T1 and T2.RESULTS: A total of 25 subjects were involved in the final analysis. ① Report accuracy in the preserved condition:Correct identification of the first target, averaged across all lags, was 94.6%. The percentages of correct identification of the second target as a function of lag was high at Lag1 (92.7%), dropped dramatically at Lag2 (79.8%), then kept improving with increase of lag, revealing a significant effect of lag [F(4,40) = 10.98, P＜ 0.01]. ② Report accuracy in the omitted condition: Correct identification of the first target T1, averaged across all lags, was 96.2%. The percentages of correct identification of the second target as a function of lag, T2 report was high at Lag1 (94.4%), decreased at Lag2(84.4%), then improved at Lag3 (91.1%), but dropped remarkably again at Lag5 and Lag7 (44.9 vs. 43.9%), revealing a significant effect of lag [F (4,52) = 224.0, P ＜ 0.01]. ③ Comparison of the results in two conditions: T2 accuracy in the omitted condition was significantly lower than that in the preserved condition at Lag5 [t (23)=34.44, P ＜ 0.01], and Lag7 [t (23)=42.56, P ＜ 0.01], but did not differ from each other at Lag1 [t (23)=0.65, P ＞ 0.05], at Lag2 [t (23)=1.04, P ＞0.05], and at Lag3 [t (23)=0.64, P ＞ 0.05].CONCLUSION: The absence of subsequent distractors after T2 can introduce a bias on the attentional status of subjects to bring the T2 accuracy down to unusual low level at long lags.