Department of Psychology
Midwestern Psychological Association’s Annual Meeting, Chicago
 May 5, 2006
Wah Pheow Tan, Jeremiah D. Still & Veronica J. Dark
For more information e-mail: wahpheow@iastate.edu
Investigating The AB Effect In An Irregular RSVP Stream
  - ---Attenuating AB With A Salient Temporal Cue
Introduction
When subjects identified two targets (T1 & T2) in a rapid serial visual presentation (RSVP) task, T2 identification is low when (a) T1 is identified, and (b) T2 appears within 500 ms of T1, a phenomenon is known as the attentional blink (AB) . Still, Tan and Dark (2006) found that a salient temporal cue prior to each target attenuated AB. The present study examined whether presenting a salient temporal cue after T1 modulates the AB.
Figure 1.RSVP Sequence Used to “Examine AB
Experiment 1
A 3 (Cue Saliency: High, Low, None) x 5 (Lag: 3-7) within subjects design was used. Lag was defined as the number of 96 msec time blocks elapsed after T1.  Subjects identified two red letters amongst black distractors. Temporal cue saliency was manipulated by varying inter-stimulus interval (ISI) of distractors between targets while keeping T1-T2 stimulus onset asynchrony (SOA) constant. When ISI is reduced,
the RSVP stream was quickened, creating the salient temporal cue.
Figure 2. Schematic Diagram of Experiment 1
Figure3. Schematic Diagram of Experiment 2
Figure 4. Experiment 1 Results
The pattern of results for both experiments were highly similar. Both T1 and T2 identification were improved by a salient temporal cue. T1 identification varied as a function of temporal saliency, while T2 identification was not affected by temporal cue saliency as both the high and low saliency conditions yielded the similar improvements. 
Figure 5. Experiment 2 Results
Discussion
Chua (2005) suggested the AB result from the failure to pass attentional control from T1 to T2. Our findings were consistent with Chua’s account. The salient temporal cue signaled T1 termination and allowed a faster attentional disengagement. Hence, the visual code of distractors appearing after T1 were less likely to undergo attentional enhancement. T1 was then better identified due to less distractor noise. When attention disengaged from T1 faster, it allowed attentional control to be passed onto T2 more rapidly. Hence, T2 was engaged earlier and AB attenuated. However, the discrepancy between the pattern of T1 and T2 identification as a function of cue saliency suggested the process of attentional disengagement from T1 and attentional engagement on T2 might be different. Further research is needed to clarify this issue.
Results
Both interference (Shapiro, Raymond & Arnell, 1994) and processing models (Chun & Potter, 1995) would predict worse T2 identification and no difference in T1 identification. The opposite was found here. Still et al. (2006) suggested a salient temporal cue prior to T1 allowed processing to begin earlier, resulting in an attenuated AB. In the current experiments, the salient temporal cue changes after T1 and do not predict target onset.
References
Chua, F. K. (2005). The effect of target contrast on the attentional blink. Perception & Psychophysics, 67(5), 770-788.
Chun, M. M., & Potter, M. C. (1995). A two-stage model for multiple target detection in rapid serial visual presentation. Journal of Experimental Psychology: Human Perception and Performance, 21(1), 109-127.
Shapiro, K. L., Raymond, J. E., & Arnell, K. M. (1994). Attention to visual pattern information produces the attentional blink in rapid serial visual presentation. Journal of Experimental Psychology: Human Perception and Performance, 20(2), 357-371.
Still, J. D., Tan, W. P., & Dark, V. J. (2006). Is the magnitude of the Attentional Blink affected by number of items or time?. Poster presented at the meeting of the Midwestern Psychological Association, Chicago, IL.
A plausible confound in Experiment 1 was the quickened RSVP stream that terminated prior T2 might cue T2 onset. In Experiment 2, distractor ISI change was localized for 192 ms after T1 offset. Hence, the terminated quickened RSVP stream no longer predict T2 onset. 
Experiment 2