Abstract
The attentional blink (AB) is consistently observed when people are required to identify or detect two consecutive targets (T1 and T2). T2 suffers in performance when it is presented less than 500 ms after T1. The two stage theory (Chun & Potter, 1995) proposes that the AB is caused by limited processing resources being occupied by T1 when T2 is presented. If so, it is expected that varying T1 difficulty should modulate the AB magnitude. Previous findings however are inconsistent: Christmann & Leuthold (2004) manipulated T1 difficulty by contrast and found that an easy T1 (high contrast) decreased the AB, but in a similar experiment Chua (2005) found the opposite. McLaughlin and colleagues (2001) varied T1 difficulty by target exposure and found no effect on the AB. In previous experiments (Nielsen, Petersen & Andersen, VSS 2009) we found no evidence of AB interference from varying T1 difficulty with contrast and exposure. We suggested that the use of pattern masks might have compromised ours, and similar studies. In a new set of experiments we test this hypothesis and vary T1 difficulty with contrast, only this time we omit T1's mask. We find significant AB interference from manipulating T1. In the easy condition (high contrast) we observe an increase in AB magnitude for SOA's of 200 ms. These findings supports the hypothesis that visual masking has an antagonistic influence on the AB effects of T1 difficulty. The result however, is the opposite of what we should expect from the two stage theory. We hypothesize that the rapid onset of T1 induces an attentional capture effect, which increases with contrast. This challenges the use of contrast to manipulate T1 in studies examining how an easy T1 affects the AB – any positive effects may be compromised by the increased capture effect.