, 2003; Jones & Forster, 2012). A repeated-measures anova was conducted selleck to compare attentional modulations with the factors Task (endogenous predictive, exogenous, endogenous counter-predictive), Cue (cued, uncued), Electrode Site (CP1/2, CP5/6, C3/4, FC1/2, FC5/6, T7/8) and Hemisphere (ipsilateral, contralateral). The electrode selection was based on electrodes close to and around the somatosensory cortex where tactile ERPs are found and attention effects on tactile processing were expected (Eimer et al., 2003; Jones & Forster, 2012, 2013b). Any significant attention modulations were correlated with behavioural RT effects to further investigate any relationship between the two
measures. The ERP effect was the average amplitude difference between cued vs. uncued trials at each component. The RT effect was similarly calculated as a difference in ms between cued and uncued trials for each participant. Correlations were only analysed for components that demonstrated a significant attention modulation. Moreover,
if the attention effect was over contralateral electrodes, then only contralateral electrodes would be correlated with RTs. Significant Cue × Electrode site interactions are only reported when warranting follow-up analyses. That is, when the effect of Cue was significant AZD8055 and also a Cue × Electrode site interaction, then this interaction was not investigated further, whilst a non-significant effect of Cue and a significant Cue × Electrode site interaction were further analysed, applying a Bonferroni correction. Partial eta squared () effect sizes are reported. Analysis of participants’ RTs to target stimuli showed there was a significant Task × Cue interaction (F2,22 = 36.82, P < 0.001, = 0.77), indicating RTs for cued and uncued trials were not the same across the three tasks. However, we were specifically interested in investigating facilitation and IOR effects in each task separately as opposite effects were predicted (Lloyd et al., 1999). Analysis of the exogenous task demonstrated
IOR, as RTs for cued trials (338.71 ms, SEM 24.99) were significantly slower compared with uncued trials (319.06 ms, SEM 22.80; t11 = −2.37, P = 0.037, = 0.34). For the endogenous predictive task, RTs to cued targets (315.32 ms, SEM 28.25) 17-DMAG (Alvespimycin) HCl were significantly faster compared with uncued targets (439.17 ms, SEM 45.54; t11 = 4.26, P = 0.001, = 0.62). Analysis of the endogenous counter-predictive task showed that RTs to uncued targets (285.78 ms, SEM 20.13) were significantly faster compared with cued targets (450.93 ms, SEM 38.10; t11 = 5.64, P < 0.001, = 0.74; Fig. 2). That is, endogenous orienting facilitated RTs at the expected location in both endogenous predictive and counter-predictive tasks. Errors were overall low, with slightly more errors in the endogenous counter-predictive task as expected. Responses to catch trials (false alarms) were 10% in the endogenous predictive, 16% in the endogenous counter-predictive and 11.
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