Weiden, Daria (2024) The Effects of Stimulus Intensity and Pupil Size on Event-related Potentials (ERPs). Bachelor thesis, Psychology.
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Abstract
The visual process is influenced by a myriad of factors. One prominent factor is the amount of light that is cast onto the retina. The amount of light that enters the eye is further determined by multiple factors. In the current study, we examined three of these factors. We aimed to investigate the effects of stimulus intensity (here operationalised as stimulus luminance), spontaneous pupil size, and pupil-size slope on the visual process as captured through electroencephalographic (EEG) signals, to investigate how an influx of light impacts visual processing. Participants (n = 10) were presented with full-monitor flashes of varying luminance for two sessions of thirty minutes. EEG signals were measured with 26 scalp electrodes. Simultaneously, pupil size and pupil size change were recorded. We found that stimulus intensity reliably affected both signal amplitude and peak latency of EEG components. Spontaneous pupil size at stimulus presentation only displayed one significant cluster in the temporal channel group, which may be a spurious result and needs replication. Pupil size slope at stimulus presentation displayed two significant clusters in central and occipital channel groups. For pupil dilation at stimulus presentation, amplitude was lower as compared to pupil constriction at stimulus presentation. No effects of pupil size slope on latency could be detected. This indicates that the visual process, at a level that EEG signals can capture, are very sensitive to changes in visual input corresponding to external stimuli, but less so for changes in bodily states, such as pupil size.
| Item Type: | Thesis (Bachelor) |
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| Supervisor name: | Mathot, S. and Dimigen, O.C. |
| Degree programme: | Psychology |
| Differentiation route: | None [Bachelor Psychology] |
| Date Deposited: | 30 Jul 2024 07:34 |
| Last Modified: | 30 Jul 2024 07:34 |
| URI: | http://gmwpublic.studenttheses.ub.rug.nl/id/eprint/4183 |
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