| 1. |
- Nordin, Steven, et al.
(author)
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Evaluation of auditory, visual and olfactory event-related potentials for comparing interspersed- and single-stimulus paradigms
- 2011
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In: International Journal of Psychophysiology. - : Elsevier. - 0167-8760 .- 1872-7697. ; 81:3, s. 252-262
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Journal article (peer-reviewed)abstract
- Background: An interspersed-stimulus paradigm (ISP) for event-related potential (ERP) recordings in which different sensory modality stimuli are presented within the same test session was developed to minimize recording time and facilitate modality comparison. The present study compared the ISP with a single-stimulus paradigm (SSP), using auditory, visual, and olfactory stimuli. Method: Normal participants (n=16) were assessed on two independent test occasions to obtain data on inter-paradigm and test-retest reliability. Peak amplitude/latency and area measures were obtained for the N1, P2 and P3 peaks for each paradigm. Results: Except for larger auditory and visual P3 peaks and smaller visual P2 peaks in the ISP, no significant differences in amplitudes or latencies were found between the two paradigms. Correlation coef ficients between paradigms were generally fairly high (amplitude mean r=0.76; latency r=0.42). Test–retest reliability within paradigms for amplitudes (ISP r=0.70; SSP r=0.68) and latencies (ISP r=0.44; SSP r=0.42) was similar across paradigms. Conclusion: Thefindings suggest that the ISP, compared to the SSP, produces, in general, highly comparable auditory, visual, and olfactory peak amplitudes and latencies, and comparable reliability estimates, even though the ISP takes much less time to record (25 vs. 50 min). The larger auditory and visual P3 peaks and smaller visual P2 peaks in the ISP may be attributable to a less predictable stimulus environment. Thus, this method enables systematic comparisons of ERP peaks across sensory modalities while reducing testing time. Practical implications are discussed.
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| 2. |
- Rosencrantz, Bella, et al.
(author)
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Affective visual event-related potentials : arousal, valence, and reptition effects for normal and disorted pictures
- 2008
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In: International Journal of Psychophysiology. - : Elsevier. - 0167-8760 .- 1872-7697. ; 67:2, s. 114-123
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Journal article (peer-reviewed)abstract
- Event-related potentials (ERPs) were used to assess arousal (low, high), valence (negative, positive), and stimulus repetition effects for normal and distorted images from the International Affective Pictures System (IAPS). Distorted stimuli were constructed by dividing each image into small squares and rearranging the segments randomly to produce a "scrambled" picture. Event-related potentials (ERPs) were elicited by presenting the normal and scrambled images as target stimuli, with a repeated visual pattern used as the standard stimulus. Participants (N=32) were instructed to press a button to the targets and ignore the standard. Stimulus repetition effects were assessed by presenting each stimulus twice in the normal and scrambled condition. High-arousal stimuli yielded larger late positive components for both the normal and scrambled pictures. No overall valence effects were obtained, but arousal and valence influenced component amplitudes for middle-latency ERPs from the scrambled stimuli. For the normal pictures, stimulus repetition was associated with increased component amplitudes for all potentials and decreased RTs of all affective categories. For the scrambled pictures, no repetition changes were obtained. The findings suggest that stimulus arousal level contributes more than valence to affective ERP measures for normal as well as perceptually distorted pictures. Stimulus repetition engages memory for previous normal picture items but is not influenced by affective category. Theoretical implications are discussed.
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