Distraction occurs when voluntary focus is disrupted by bottom-up influences on attention and must be reoriented back to task-relevant goals. Human neuroimaging studies suggest that the right temporo-parietal junction (TPJ) plays a critical role in the reorienting of attention following distraction (e.g. Corbetta & Shulman, 2002). However, the neural processes by which distraction affects perception and subsequent actions are unclear. Here, we investigated the neural mechanisms of distraction when attention is differentially captured by a distracting stimulus; specifically, when attention is involuntarily oriented to versus held on a task-irrelevant item. First, we conducted two behavioral studies (Experiments 1 & 2) to determine experimental conditions that held attention, versus those that simply oriented attention. We provided novel results that neutral faces involuntarily hold attention a greater extent than places, increasing distraction. Using fMRI, we then examined differences in neural activity between these conditions to investigate the neural correlates of involuntary orienting and hold (Experiment 3). Lastly, we explored whether attentional hold effects would manifest in a traditional spatial cuing paradigm (Experiments 4a & 4b). fMRI analyses revealed a hemispheric asymmetry in the brain regions involved in the reorienting of attention. Activity in the right TPJ was enhanced for distractors that oriented and held attention, as compared to distractors that only oriented attention. Further, these same distractors produced activation in the left TPJ, while distractors that merely oriented attention did not. These novel results might add to previous studies of reorienting in which TPJ activation was limited to the right hemisphere. We suggest that in these prior studies, attention was oriented to distractors, but may not have been held to the extent required to elicit left TPJ activation. The absence of hold may have led to the right-dominant activity observed. Further, using a traditional cuing paradigm, we found no evidence of extended hold, suggesting that the hold demonstrated in Experiments 1–3 did not reflect delays at early perceptual processing stages. Overall, involuntary orienting and hold were associated with different neural signatures, providing novel evidence that these two processes reflect partially distinct mechanisms.
|Advisor:||Hopfinger, Joseph B.|
|Commitee:||Boettiger, Charlotte, Giovanello, Kelly, Mulligan, Neil, Payne, Keith|
|School:||The University of North Carolina at Chapel Hill|
|School Location:||United States -- North Carolina|
|Source:||DAI-B 73/06, Dissertation Abstracts International|
|Subjects:||Experimental psychology, Cognitive psychology|
|Keywords:||Attention, Bottom-up influences, Distraction, Neural correlates, Voluntary focus|
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