Selective influence of second target exposure duration and task-1 load effects in the attentional blink phenomenon.

The purpose of the experiments was to constrain the locus of interference in the attentional blink (AB) paradigm. Two visual stimuli, T1 and T2, were shown 300 msec apart, and each was followed by a mask. T1 was an "H," an "S," an "&," or a blank field; T2 consisted of five letters. In Task1, blank fields and & characters could be ignored, whereas Hs and Ss had to be identified and reported. Task2 was always to report as many letters as possible from T2. Task2 performance was lower when T1 had to be reported, as expected from the attentional blink phenomenon (AB). The exposure duration of T2 was also manipulated. More letters could be reported as exposure duration was increased. However, this effect was additive with manipulations of Task1 processing load that produced the AB effect. Log-linear analyses assuming that effects of T2 exposure duration and Task1 load effects occur at functionally distinct stages of processing provided satisfactory fits to the results, suggesting that none of the AB effect occurs as early as those of T2 exposure duration. The results suggest that the locus of the AB effect is later than the stage(s) of processing affected by exposure duration.