Metric error monitoring: Does a common metric error monitoring ability exist for all magnitude domains and is it distinct from perceptual metacognition?

Previous research on magnitude perception suggested a commonality across different metric domains. Metric error monitoring is a field that investigates awareness of the magnitude and direction of errors. The main aim of the present thesis was to carry this commonality found in magnitude perception to metacognitive level by investigating metric error monitoring ability and its relationship with visual perceptual metacognition. The first study (Chapter 2) examined the domain-generality of metacognitive abilities across metric domains (temporal, spatial, and numerosity) and their possible relationship with perceptual metacognition measured with a two-alternative forced choice (2 AFC) task in a behavioral experiment setting. The second study (Chapter 3) investigated error magnitude awareness in a time reproduction task, as a part of metric error monitoring ability. This study employed a non-traditional way of examining metric error monitoring by using the decline choice method thus aiming to test error magnitude awareness using a more indirect method. The final study (Chapter 4) investigated the neural bases of error monitoring ability in metric and non-metric domains. Numerosity and color reproduction tasks were chosen as to test metric and visual perceptual error monitoring abilities, respectively. Based on previous literature, two target regions anterior prefrontal cortex (aPFC) and precuneus were chosen and inhibitory neurostimulation was applied to understand whether these regions are responsible for error monitoring abilities in numerosity and color domains. Results of the first study suggested a common metric error monitoring ability and sensitivity across magnitude domains (i.e., numerosity, space, and time) that was not related to visual perceptual metacognition in the 2AFC task. The second study showed that human participants were successful at using the decline choice when their performance was far from than ideal. Finally, results of the third study showed both precuneus and aPFC involvement in metacognition for numerosity, but not for color. Additionally, this influence was only observed for the accuracy of confidence judgments but not for error magnitude or direction judgments. Taken together, the results of the present thesis showed a common/shared ground across metric domains at the behavioral level. But whether this commonality originates from a common or shared neuroanatomical source is still unknown. Results also showed that humans could keep track of the magnitude of their temporal reproduction errors even when they are prompted rather covertly which supports the idea that error monitoring mechanisms might be working automatically. Finally, behavioral and neuromodulation findings suggested that error monitoring abilities in numerosity and color domains were governed by distinct neural mechanisms, as did the error direction and confidence judgments within the numerosity domain.