Kontextabhängigkeit metakognitiver Sensitivität und Entscheidungssicherheit

Visual perception can be described as a choice process which is characterized by objective performance in a discrimination task and metacognitive evaluations of choice certainty. For every perceptual choice, a subject evaluates their certainty concerning the outcome. Metacognitive sensitivity reflects how reliably the subjective choice certainty reflects objective performance. In this thesis we investigated the effects of artificial visual impairment on performance, choice certainty and metacognitive sensitivity in a visual discrimination task. For 27 healthy emmetropic human subjects we examined the effect of an unphysiological refraction (achieved with lenses of 2+ dpt) in combination with two different stimulus durations (100ms or 500 ms). The first paradigm examined motion discrimination. The subjects were supposed to discriminate the global motion direction in a random dot kinematogram (RDK) for different levels of coherence. In a second step, they indicated their confidence via button press. In the second paradigm, Landolt rings of different sizes were presented and the subjects indicated the gap of the ring and with the second button press they indicated their confidence. In these experiments, refraction showed a strong influence on visual acuity, but motion discrimination was not significantly impaired. A shorter stimulus duration caused significant perceptual impairment in both paradigms. For both stimuli, a change in objective performance was accompanied by changes of subjective confidence in it and of metacognitive sensitivity. The profound perceptual impairment caused by artificial refraction or shorter stimulus presentation did not cause a dissociation of these three measures. This thesis shows that a change in confidence reflects a visual disturbance. The reduction of metacognitive sensitivity means that a patient with a visual disturbance has also impaired knowledge about their deficit. If these changes can be found in a clinical context with organic visual impairment as well has yet to be shown