Upshifted decision criteria in attentional blink and repetition blindness

A large number of “unawareness” phenomena have been explained and quantified in terms of sensitivity (d′) fluctuations, with very few attempts at addressing an alternative putative cause, i.e., fluctuations of subjects’ response criteria (c). Response criteria fluctuations are particularly likely under dual-task paradigms with unbalanced sensitivities (Gorea & Sagi, 2000) such as those used in evidencing attentional blink (AB) and repetition blindness (RB) phenomena. The present study inquires into whether AB and RB are indeed prone to a deviant decisional behaviour. AB and RB were studied with a yes/no task allowing the assessment of d′ and c for the detection (presence/absence) of a target letter T2 as a function of its temporal lag relative to the presentation of another (AB) or of the same (RB) letter, T1 (Experiment 1). A significant criterion increase was observed in both cases. Additional experiments demonstrate that this criterion effect is typical of these dual-task AB and RB paradigms as it is not observed in a standard contrast detection task with mixed contrasts (Experiment 2), in a “control” AB design stripped off its first task T1 (Experiment 3), or in a metacontrast experiment (Experiment 4). We propose that the observed criterion shifts are the consequence of the inherent dual-task AB and RB designs (where observers have to judge two events of unequal saliencies) and that they entail an enhancement of the AB and RB effects as long as these effects are assessed via subjective (yes/no or matching) procedures.