Objective: To investigate visual motion perception as a potential contributor to impaired visual self-motion perception in PD. To measured metacognitive ability and bias in PD when estimating their own perceptual function.

Background: Impaired sensory and perceptual processes are understudied aspects of Parkinson’s disease (PD). Recently our group has shown impaired self-motion perception in PD specific to the visual modality as well as overweighting of this modality in multi-sensory perception.

Method: The participants (N=20 PD patients, N=20 aged-matched and N=20 young healthy controls) were required to determine the aggregate motion of dots (rightward/leftward) in a two-alternative forced choice task in a computer monitor (visual stimuli comprised 2D random dot kinematogram (RDK) of varying coherence). After each RDK discrimination, participants also indicated their confidence level (low/high) in their decision (Figure 1). For cognitive function control, we evaluated all subjects using the Montreal Cognitive Assessment test.

Results: Patients with PD did not have different visual motion thresholds in comparison to the control groups (p=0.11). Despite comparable RDK thresholds, PD patients exhibited higher confidence in their choices vs. each of the control groups (p≤0.02). No significant difference in cognitive function was seen between the PD and control groups (p= 0.06). See Figure 2 for example single subject results and Figure 3 for group results.

Conclusion: Our finding that PD patients did not show an impairment of 2D visual motion perception, suggests that our previous finding of impaired 3D visual self-motion perception is not due to a general impairment of visual motion perception. In addition, our finding of overconfidence in visual performance in PD patients might underlie accounts of increased visual dependency in PD. To assess whether perceptual confidence is generally increased in PD (vs. vision specific), metacognition needs to be tested also using other cues and tasks.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/visual-motion-perception-and-metacognition-in-parkinsons-disease/