This study investigated the influence of action-associated predictive processes on visual ERPs. In two experiments, we sought evidence for sensory attenuation (SA) indexed by ERP amplitude reductions for self-induced stimuli when compared to passive viewing of the same images. We assessed if SA is (a) present for both ecological and abstract stimuli (pictures depicting hands or checkerboards), (b) modulated by the degree of stimulus predictability (certain or uncertain action-effect contingencies), and (c) sensitive to laterality of hand movements (dominant or subdominant hand actions). We found reduced occipital responses in the early 77-90 ms time interval (C1 component), irrespective of stimulus type, predictability, or the laterality of hand movements. However, the subsequent P1 component was increased (rather than reduced) for all action-associated stimuli. In addition, this P1 effect was influenced by the degree of stimulus predictability for ecological stimuli only. Finally, the posterior N1 component was not modulated by self-initiated actions. Overall, our findings indicate that movement-related predictive processes attenuate early visual responses. Moreover, we propose that amplitude modulations in the P1 time range reflect the interaction between expectation-based SA and attention-associated amplitude enhancements. These results can have implications for assessing the influence of action-associated predictions on visual processing in psychiatric disorders characterized by aberrant sensory predictions and alterations in hemispheric asymmetry, such as schizophrenia.

More than a dozen studies of the Complex Trial Protocol (CTP) version of the P300-based Concealed Information Test have been published since its introduction (Rosenfeld et al., 2008), and it has been fairly consistently proven to provide high accuracy and strong resistance to countermeasures . However, no independent authors have verified these findings until now. In the present, first independent study, we corroborate the accuracy and countermeasure-resistance of the CTP, when the probe item (critical presented information, e.g., crime detail; P) vs. all irrelevant items (Iall) comparison is used for classifying participants as guilty or innocent, but we also show that the CTP is severely vulnerable to countermeasures, when the P vs. the irrelevant item with the largest P300 responses (Imax) comparison is used.This latter measure can be defeated by creating "oddball" items among the irrelevant items (through targeting them with covert responses), and thereby making their P300 responses statistically indistinguishable from those of the probe item. Practical implications are discussed.

More than a dozen studies of the Complex Trial Protocol (CTP) version of the P300-based Concealed Information Test have been published since its introduction (Rosenfeld et al., 2008), and it has been fairly consistently proven to provide high accuracy and strong resistance to countermeasures . However, no independent authors have verified these findings until now. In the present, first independent study, we corroborate the accuracy and countermeasure-resistance of the CTP, when the probe item (critical presented information, e.g., crime detail; P) vs. all irrelevant items (Iall) comparison is used for classifying participants as guilty or innocent, but we also show that the CTP is severely vulnerable to countermeasures, when the P vs. the irrelevant item with the largest P300 responses (Imax) comparison is used.This latter measure can be defeated by creating "oddball" items among the irrelevant items (through targeting them with covert responses), and thereby making their P300 responses statistically indistinguishable from those of the probe item. Practical implications are discussed.

This study investigated the influence of action-associated predictive processes on visual event-related potentials (ERPs). In two experiments (N=17 and N=19), we sought evidence for sensory attenuation (SA) indexed by ERP amplitude reductions for self-induced stimuli when compared to passive viewing of the same images. We assessed if SA (1) is stronger for ecologically valid versus abstract stimuli (by comparing ERPs to pictures depicting hands versus checkerboards), (2) is specific to stimulus identity (certain versus uncertain action-effect contingencies), and (3) is sensitive to laterality of hand movements (dominant versus subdominant hand actions). We found reduced occipital responses for self-triggered hand stimuli very early, between 80-90 ms (C1 component), but this effect was absent for checkerboards. On the contrary, the P1 component (100-140 ms) was enhanced for all action-associated stimuli, and this effect proved to be sensitive to stimulus predictability for hands only. The parietal N1 component (170-190 ms) showed amplitude enhancement after right-hand movements for checkerboards only. Overall, our findings indicate that action-associated predictive processes attenuate early cortical responses to ecologically valid visual stimuli. Moreover, we propose that subsequent ERPs show amplitude enhancement that might result from the interaction between expectation-based SA and attention. Movement-initiated modulation of visual ERPs does not appear to show strong lateralization in healthy individuals, although the absence of lateralized effects cannot be excluded. These results can have implications for assessing the influence of action-associated predictions on visual processing in psychiatric disorders characterized by aberrant sensory predictions and alterations in hemispheric asymmetry, such as schizophrenia.

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