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Disentangling neural processing of masked and masking stimulus by means of event-related contralateral - ipsilateral differences of EEG potentials.

Verleger R, Jaśkowski P - Adv Cogn Psychol (2008)

Bottom Line: Their major component, the N2pc, is interpreted as indicating preferential processing of stimuli matching the target template, which process can neither be identified with conscious perception nor with shifts of spatial attention.The measurements showed that the triggering of response preparation by the masked stimuli did not depend on their discriminability, and their priming effects on the processing of the following target stimuli were qualitatively different for stimulus identification and for response preparation.These results provide another piece of evidence for the independence of motor-related and perception-related effects of masked stimuli.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University of Lübeck, Germany.

ABSTRACT
In spite of the excellent temporal resolution of event-related EEG potentials (ERPs), the overlapping potentials evoked by masked and masking stimuli are hard to disentangle. However, when both masked and masking stimuli consist of pairs of relevant and irrelevant stimuli, one left and one right from fixation, with the side of the relevant element varying between pairs, effects of masked and masking stimuli can be distinguished by means of the contralateral preponderance of the potentials evoked by the relevant elements, because the relevant elements may independently change sides in masked and masking stimuli. Based on a reanalysis of data from which only selected contralateral-ipsilateral effects had been previously published, the present contribution will provide a more complete picture of the ERP effects in a masked-priming task. Indeed, effects evoked by masked primes and masking targets heavily overlapped in conventional ERPs and could be disentangled to a certain degree by contralateral-ipsilateral differences. Their major component, the N2pc, is interpreted as indicating preferential processing of stimuli matching the target template, which process can neither be identified with conscious perception nor with shifts of spatial attention. The measurements showed that the triggering of response preparation by the masked stimuli did not depend on their discriminability, and their priming effects on the processing of the following target stimuli were qualitatively different for stimulus identification and for response preparation. These results provide another piece of evidence for the independence of motor-related and perception-related effects of masked stimuli.

No MeSH data available.


Contralateral-ipsilateral differences in ERPs evoked by the sequence of						primes and targets, from 100 ms before prime onset until 1 s afterwards,						with contralateral and ipsilateral defined with respect to side of the						relevant element in the target, = side of the response. Grand means across						12 participants. Trials with 83 ms SOA between primes and targets are						compiled in the left half, trials with 167 ms in the right half. “Congruent”						means that the relevant shape was on the same side in primes as in targets,						“incongruent” means different sides, “neutral” denotes two irrelevant shapes						in the primes. Each panel displays difference waveshapes between a pair of						symmetrical left and right positions, from anterior sites of the scalp (top)						to occipital sites (2nd panels from bottom). The bottom panels						display the time course of the forces exerted on the response keys						(identical to Figure 1).
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Figure 5: Contralateral-ipsilateral differences in ERPs evoked by the sequence of primes and targets, from 100 ms before prime onset until 1 s afterwards, with contralateral and ipsilateral defined with respect to side of the relevant element in the target, = side of the response. Grand means across 12 participants. Trials with 83 ms SOA between primes and targets are compiled in the left half, trials with 167 ms in the right half. “Congruent” means that the relevant shape was on the same side in primes as in targets, “incongruent” means different sides, “neutral” denotes two irrelevant shapes in the primes. Each panel displays difference waveshapes between a pair of symmetrical left and right positions, from anterior sites of the scalp (top) to occipital sites (2nd panels from bottom). The bottom panels display the time course of the forces exerted on the response keys (identical to Figure 1).

Mentions: Figure 5 displays the difference waveshapes between symmetrical scalp sites contralateral minus ipsilateral to the relevant shape in the target. In our first report of these data (Jaśkowski et al., 2002) we reported results from selected intervals of variable length. Here we will provide a more systematic view on these data, by conducting ANOVAs on 25 ms intervals of these hemispheric differences, as was done above with conventional ERPs, with the factors SOA (83 / 167) and Congruence (congruent, neutral, incongruent). (Representing differences between hemispheres, these data do not include the former third factor, Hemisphere, any more.)


Disentangling neural processing of masked and masking stimulus by means of event-related contralateral - ipsilateral differences of EEG potentials.

Verleger R, Jaśkowski P - Adv Cogn Psychol (2008)

Contralateral-ipsilateral differences in ERPs evoked by the sequence of						primes and targets, from 100 ms before prime onset until 1 s afterwards,						with contralateral and ipsilateral defined with respect to side of the						relevant element in the target, = side of the response. Grand means across						12 participants. Trials with 83 ms SOA between primes and targets are						compiled in the left half, trials with 167 ms in the right half. “Congruent”						means that the relevant shape was on the same side in primes as in targets,						“incongruent” means different sides, “neutral” denotes two irrelevant shapes						in the primes. Each panel displays difference waveshapes between a pair of						symmetrical left and right positions, from anterior sites of the scalp (top)						to occipital sites (2nd panels from bottom). The bottom panels						display the time course of the forces exerted on the response keys						(identical to Figure 1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2864968&req=5

Figure 5: Contralateral-ipsilateral differences in ERPs evoked by the sequence of primes and targets, from 100 ms before prime onset until 1 s afterwards, with contralateral and ipsilateral defined with respect to side of the relevant element in the target, = side of the response. Grand means across 12 participants. Trials with 83 ms SOA between primes and targets are compiled in the left half, trials with 167 ms in the right half. “Congruent” means that the relevant shape was on the same side in primes as in targets, “incongruent” means different sides, “neutral” denotes two irrelevant shapes in the primes. Each panel displays difference waveshapes between a pair of symmetrical left and right positions, from anterior sites of the scalp (top) to occipital sites (2nd panels from bottom). The bottom panels display the time course of the forces exerted on the response keys (identical to Figure 1).
Mentions: Figure 5 displays the difference waveshapes between symmetrical scalp sites contralateral minus ipsilateral to the relevant shape in the target. In our first report of these data (Jaśkowski et al., 2002) we reported results from selected intervals of variable length. Here we will provide a more systematic view on these data, by conducting ANOVAs on 25 ms intervals of these hemispheric differences, as was done above with conventional ERPs, with the factors SOA (83 / 167) and Congruence (congruent, neutral, incongruent). (Representing differences between hemispheres, these data do not include the former third factor, Hemisphere, any more.)

Bottom Line: Their major component, the N2pc, is interpreted as indicating preferential processing of stimuli matching the target template, which process can neither be identified with conscious perception nor with shifts of spatial attention.The measurements showed that the triggering of response preparation by the masked stimuli did not depend on their discriminability, and their priming effects on the processing of the following target stimuli were qualitatively different for stimulus identification and for response preparation.These results provide another piece of evidence for the independence of motor-related and perception-related effects of masked stimuli.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University of Lübeck, Germany.

ABSTRACT
In spite of the excellent temporal resolution of event-related EEG potentials (ERPs), the overlapping potentials evoked by masked and masking stimuli are hard to disentangle. However, when both masked and masking stimuli consist of pairs of relevant and irrelevant stimuli, one left and one right from fixation, with the side of the relevant element varying between pairs, effects of masked and masking stimuli can be distinguished by means of the contralateral preponderance of the potentials evoked by the relevant elements, because the relevant elements may independently change sides in masked and masking stimuli. Based on a reanalysis of data from which only selected contralateral-ipsilateral effects had been previously published, the present contribution will provide a more complete picture of the ERP effects in a masked-priming task. Indeed, effects evoked by masked primes and masking targets heavily overlapped in conventional ERPs and could be disentangled to a certain degree by contralateral-ipsilateral differences. Their major component, the N2pc, is interpreted as indicating preferential processing of stimuli matching the target template, which process can neither be identified with conscious perception nor with shifts of spatial attention. The measurements showed that the triggering of response preparation by the masked stimuli did not depend on their discriminability, and their priming effects on the processing of the following target stimuli were qualitatively different for stimulus identification and for response preparation. These results provide another piece of evidence for the independence of motor-related and perception-related effects of masked stimuli.

No MeSH data available.