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The deployment of visual spatial attention during visual search predicts response time

electrophysiological evidence from the N2pc


doi: 10.1097/WNR.0000000000000742
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In the original article published in the November issue 1, an arithmetic mistake introduced a systematic error in the stated results. The authors would also like to note that in the methods section, for the colour of the target, the percentages should be 20% for the infrequent colour and 80% for the frequent colour instead of 25% and 75%, respectively. Importantly, the interpretations and outcomes of all statistics remain the same as well as all scientific conclusions. The corrections to the statistics, table, and figure are below.

The authors apologise for these errors.

Behavioural results

The overall mean response time (RT) of 627.5 ms (SE=11.2 ms) is corrected to 669.9 ms (SE=12.11). An interaction for between-subject response speed and within-subject response speed was observed: Slower responders showed a larger difference between the slow RT and fast RT trials (ΔRT=241.2 ms) in comparison with fast responders (ΔRT=135.6 ms), F (1, 86)=37.05, P<0.0001.

Electrophysiological results

Fast responders showed an earlier and larger N2pc in comparison with slow responders [amplitude: F (1, 86)=4.35, P<0.04; latency: F (1, 86)=5.08, P<0.03]. Fast response trials also had a larger and earlier N2pc in comparison with slow response trials [amplitude: F (1,86)=21.34, P<0.0001; latency: F (1, 86)=8.95, P<0.004]. No interaction was observed for amplitude (F (1, 86)=0.80, P=0.37) or latency (F (1, 86)=1.38, P=0.24). Both N2pc amplitude and latency were positively correlated with RT (r=0.33, P<0.002; r=0.23, P<0.04, respectively). Fast responders showed a higher mean variance in the N2pc amplitude than slow responders (fast responders SE=0.24; slow responders SE=0.16), scaling with the mean. For N2pc latency, slow responders had a higher mean variance than fast responders (fast responders SE=3.44; slow responders: SE=3.72) (Table 1 and Fig. 2).

Table 1
Table 1:
Means and standard errors for response time, N2pc amplitude and N2pc latency, for fast and slow responses by fast and slow responders
Fig. 2
Fig. 2:
Lateralised event-related potential waveforms (at PO7/PO8) for fast and slow responses and whether participants were fast or slow responders. Fast responders are identified by a thicker line in comparison with slow responders. Fast responses are identified by a continuous line, whereas slow responses are identified by a dashed line. Each waveform was obtained by subtracting ipsilateral activity from contralateral activity. The N2pc can be observed in these difference waveforms as the first large negative deflection (peak between 200 and 300 ms).


1. Drisdelle BL, West GL, Jolicoeur P. The deployment of visual spatial attention during visual search predictsresponse time: electrophysiological evidence from the N2pc. Neuroreport 2016; 27:1237–1242.
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