Subsequent Search Misses in Visual Search: Brain Stimulation Study

Subsequent search misses» (SSM) are a decrease in accuracy at detecting a second target after a first target in visual search task. The aim of this study is to investigate the possibility to modulate this effect with the inhibition of the right posterior parietal area. The target stimuli are perfectly aligned T-shapes present among perfectly aligned and not perfectly aligned L-shaped distractors. The participant’s task is to find all targets or to report their absence. On each trial, it could be one high-salient target, one low-salient target, two targets - one high salient and one low salient, two high salient targets, two low salient targets, or no targets at all (catch-trials). Transcranial direct current stimulation (tDCS) includes 3 conditions of stimulation: cathodal stimulation of the right posterior parietal area, cathodal stimulation of the left posterior parietal area, sham on the right posterior parietal area. The stimulation intensity is 1500 μA. The offline protocol of stimulation is applied: the stimulation lasts for 10 minutes and finishes before the main session of the experiment. The results of the study showed that the type of stimulation did not affect the amplitude of the effect, but there are differences between the conditions of different amounts of targets, which indicates the presence of the effect of «subsequent search misses».