Evidence suggests that both the above experimental situations can lead to an AB, although whether or not an AB occurs depends to a considerable extent on the method employed. One final question is whether an AB exists within other modalities (audition, touch) such as exists in the visual modality and whether cross-modal (between modalities e.g., visual T1, auditory T2) AB’s exist. Although it might be expected that the AB should be maximal immediately following T1, a phenomenon referred to as lag-1 sparing often arises, where T2 accuracy is preserved when T2 occurs immediately after T1. Finally, the issue of T1 difficulty and its effect on the AB has been heavily investigated with some investigators finding a relationship between T1 difficulty and the magnitude of the AB (e.g., Seiffert & Di Lollo, 1997 Ward Duncan, & Shapiro, 1997) and others not (McLaughlin, Shore, & Klein, 2001). Moreover, Giesbrecht and Di Lollo (1998) showed that T2 must be appropriately masked simply degrading T2 does not produce an AB. However, Visser (2007) discovered an AB can be obtained without the use of a T1 mask, though the T1 task was novel and thus likely more difficult. (1992) found that removing the T1 mask completely attenuated the AB. In a related issue, the vast majority of published reports have employed a mask (typically the item in the RSVP stream succeeding each target) as Raymond et al. T2 mask, suggesting the role played by the mask is different for each target. Seiffert & Di Lollo (1997) concluded there are different requirements for the nature of the T1 vs. Another issue investigated has been the importance of masking both T1 and T2. Although such a ‘skeletal’ procedure is far less often employed than the typical RSVP stream procedure, nevertheless, an AB does result. To investigate this Ward, Duncan, and Shapiro (1997) presented masked targets, but without any other stimuli, in the centre of a visual display and obtained an AB outcome, though not revealing the typical AB function (see lag-1 sparing below). The question is often asked, “What are the requirements to produce an AB?” One issue that has been investigated is whether the full RSVP stream is required. Adding a task switch between T1 and T2 may add to the T2 deficit. The AB occurs even when T1 and T2 involve the same task and are presented in the same location (e.g., Chun & Potter, 1995). Finally, task switching costs and spatial switching costs are also different from the AB. The duration and capacity of visual short-term memory (VSTM), however, makes this account unlikely. Another possible explanation is that the AB is not due to a failure of attention but to a failure to retain memory of the two targets until prompted for report at the trial end. This control also points out that the AB is not due simply to better performance at the end of the RSVP stream as opposed to the beginning, i.e., a recency effect. No AB occurred in this condition suggesting attention to T1 and not perceptual masking accounts for the AB outcome. (1992) implemented a control condition where the stimuli were the same as in the experimental condition described above – thus equating the two conditions perceptually – but participants were not required to report T1. Given that the RSVP stream containing the two targets is flashing by at 10 items per second, one possible account of the AB is that the task is perceptually too demanding, with each item potentially masking the preceding item. The AB is defined as having occurred when T1 is reported correctly but report of T2 is inaccurate at short T1/T2 intervals, typically between ~100 to 500 ms, but recovers to the baseline level of accuracy at longer intervals (see Figure 3). Report of both targets was required after the stimulus stream ended. T2 was presented on only 50% of trials and when presented, occurred with an interval separating the two targets of between 100 to 800 ms. (1992), participants were required to identify the only white letter (first target T1) in the 10-item per second RSVP stream of black letters (non-targets or distractors), then to report whether the letter ‘X’ (second target T2) occurred in the subsequent letter stream (see Figure 1 for a static example and Figure 2 for a slowed dynamic example). In the procedure derived by Raymond et al. The basic AB paradigm employs a method known as rapid serial visual presentation (RSVP) where stimuli such as letters, digits, or pictures are presented successively at a single location at rates between 6 – 20 items per second. The ‘attentional blink’ (AB) was first described by Raymond, Shapiro, & Arnell (1992), though reports published prior to this revealed the existence of the same outcome (e.g., Broadbent & Broadbent, 1987) but did not use this term.
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