Browsing by Author "Rehn, Jasmin"

Background: We studied two different visual effects: In brightness induction, the perceived brightness of the stimulus is altered by the luminance of its surround, and in orientation selective contrast suppression the contrast of the stimulus appears lower when surrounded by a collinear surround of higher contrast. In previous studies, orientation selective contrast suppression has been found to be altered in patients who have been diagnosed with depression. Objectives: We measured symptoms of anxiety and depression in our non-clinical sample in order to compare them to their performance in the visual experiments. The goal of our online experiment was also to replicate both of the visual effects without a tightly controlled environment. Methods: Our online experiment consisted of a repeated measures design, with separate blocks for randomised brightness trials, randomised contrast trials, and self-report mental health questionnaires. In the visual trials participants were asked to estimate the brightness or contrast level of a central stimulus, while its surround was varied in luminance or contrast. Our sample consisted of 76 healthy participants with a mean age of 25. Results and conclusions: We managed to replicate both the brightness induction and the orientation selective contrast suppression effects, and found that the use of different electronic devices in completion of the study had no significant effect on the results. Participants reported varying levels of symptoms of anxiety and depression, and 61.6 % of them crossed clinically relevant cut-off points. We did not find a statistically significant connection between the visual effects and symptoms of anxiety and depression. This is encouraging, as it indicates that having only a few symptoms of mental disorders does not alter contrast perception. However, finding out at what point is the contrast perception altered, warrants further study.