Abstract
Introduction & Goal: Negative Priming (NP) refers to a decrement in performance (reaction time) in response to an item that has been previously ignored and which is now being presented as the target. Recently, Carrasco & McElree (2001) demonstrated that attention speeds up information accrual at the attended areas. Moreover, Frieder & Carrasco (2001) showed that NP for unfamiliar shapes occurs even for short display durations (< 200ms) under covert attention conditions. In this study, for the first time we explore how information accrues over time for attended and unattended shapes under covert attention.
Method: We used time-course functions derived from the response-signal speed-accuracy trade-off (SAT) procedure and a modified NP task that requires a symmetry judgment of a target. Observers viewed a series of displays with a pair of overlapping novel shapes (a green target overlapping a red distracter) presented in the center of the screen, and were asked to determine whether the target was symmetrical or not. In a negative priming paradigm, unbeknownst to the observers, in a third of the trials the red overlapping distractor re-appeared as the green target in the following trial (distracter-->target). In another third of the trials the green target appeared as the target again (target→target). In the rest of the trials (control condition) all the shapes were novel.
Observers were prompted with a visual cue to respond to the display at different time lags, ranging from 100ms to 1000 ms, following the display presentation.
Results & Conclusion. Reaction times and accuracy data were analyzed using the SAT procedure, which provides information regarding both discriminability and temporal dynamics. The rate of information processing was slower for unattended shapes than for attended ones. These results shed light in the mechanisms underlying the NP effect and provide a unique new theoretical and methodological framework for the study of the NP effect.