Impact of Movement Amplitude in Dynamic Visual Cues on Motor Imagery Ability and BCI Classification

Motor imagery-based brain-computer interface (MI-BCI) is an important research topic in the field of motor function rehabilitation. Although dynamic visual cues can modulate motor imagery (MI) performance, the role of movement amplitude remains underexplored. This study investigated the effects of movement amplitude in dynamic visual cues on MI ability and MI-BCI classification performance. Participants performed right-hand MI tasks cued by dynamic visual stimuli with three amplitudes: large (60°), medium (40°), and small (20°). Subjective kinesthetic imagery vividness, beta-band Event-related desynchronization (ERD), and classification accuracy were measured. Large-amplitude visual cues significantly enhanced KMI vividness scores (3.14 ± 0.85), elicited stronger MI-related cortical activation (beta-band ERD: −6.92 ± 9.97), and achieved higher MI-BCI classification accuracy (e.g., beta-band accuracy: 93.45% ± 5.37%) compared with medium and small amplitudes. These findings suggest that dynamic visual cue amplitude is associated with improved MI performance and provide practical guidance for optimizing MI-BCI training and rehabilitation-oriented HCI design.