Abstract
Identification of the second of two targets (T1, T2) is impaired when presented within about 500 ms of the first (attentional blink, AB). Ghorashi et al. (2007) found that temporally leading exogenous spatial cues presented at the T2 location facilitated T2 identification but did not reduce the AB magnitude. They reasoned that exogenous spatial cues are processed along the dorsal visual pathway whereas target identity is processed along the ventral pathway. Thus, cue and target were processed separately. It follows that, were the cue and T1 to be processed along the ventral pathway, cue-processing should suffer during the AB. To test this hypothesis, two types of spatial cues were used, both with an endogenous component but differing in dorsal- versus ventral-stream processing. In Experiment 1, T1 was a white letter in an RSVP stream of black letters. T2 was a tilted “T” among rotated “L”s, all positioned on an imaginary clock-face (2.5° radius), centered on fixation. Observers indicated whether the “T” was tilted left or right. On half the trials, a small dot (dorsal stream) was presented 100 ms before T2, at the clock-face location opposite T2. Participants were instructed to use the cue to find the “T” at the clock location opposite the cue. The results showed that this patial cue could be processed efficiently even during the AB. In Experiment 2, the cue was a red number between 1 and 12 (ventral stream) that indicated the location of T2 on the clock-face. The number appeared briefly just above fixation 100 ms before T2. Processing of this spatial cue was impaired during the AB. These results support the initial hypothesis that whether or not processing of a spatial cue is impaired during the AB depends on whether it is processed along the same (ventral) pathway as T1.
This research was supported by NSERC grants to Vincent Di Lollo and James T. Enns.