Abstract:
The ability to select and attend to visual stimuli has been studied extensively, including through the use of human electrophysiology, or EEG. Through EEG, we are able to look at time-locked events called ERPs, to attribute different mechanisms of cognitive processing. Specifically, ERPs which are 'lateralised' address potential visual biases through balancing the hemispheric activity. Lateralised components related to selective attention include the N2pc, a negative component which relates to the initial attention to the stimuli, the Ptc, which relates to distractor suppression behaviour, and the SPCN, which relates to visual short-term memory. Prior research suggests that the Ptc reflects mechanisms involved in distractor suppression or disengagement, although the specificity of the Ptc is still unclear. In this experiment, we explored the effects of repeating the location of distractor items on behavioural performance and the lateralised components, mainly with the Ptc. We found that there was an increased Ptc amplitude with more repetitions of the distractor location, while with less repetitions the Ptc was smaller but wider. This suggests that the Ptc may not be representative of the effort and difficulty to suppress distractors, but rather representative of the response times. There was also evidence from the behavioural results which supported the Ptc amplitudes, in which participants were faster with more repetitions. This gives evidence that increased repetitions would result in larger Ptc amplitudes, while less repetitions result in smaller but wider amplitudes, as the response times varied and spread out for more difficult trials. Notably, it was also found that while repetition contributed to the increased Ptc amplitude, the N2pc and the SPCN remained unaffected, thereby providing further evidence that the Ptc can be dissociated from these other components through being specifically related to the suppression of distraction.
