Modeling direction discrimination thresholds for yaw rotations around an earth-vertical axis for arbitrary motion...

Area of Science:

• Neuroscience
• Human Perception
• Biomechanics

Background:

• Vestibular perception dynamics are vital for virtual reality and diagnosing vestibular disorders.
• Previous studies linked rotational motion discrimination to stimulus period length but not shape.
• No models accounted for non-sinusoidal rotational motion stimuli.

Purpose of the Study:

• Investigate the influence of period length and time course of inertial stimuli on rotational motion perception.
• Determine if acceleration profile shape affects direction discrimination thresholds.
• Develop a novel model for rotational motion perception based on semi-circular canal neuron activity.

Main Methods:

• Measured direction discrimination thresholds for yaw rotation under triangular, sinusoidal, and trapezoidal acceleration profiles.
• Tested three period lengths (0.3, 1.4, 6.7 s) in ten participants using a two-alternative forced-choice task.
• Varied peak stimulus velocity and defined thresholds at 75% correct responses.

Main Results:

• Thresholds decreased with shorter period lengths, from ~2 deg/s (6.7 s) to ~0.8 deg/s (0.3 s).
• Peak velocity was the primary determinant of discrimination thresholds.
• Different acceleration profiles with the same period length yielded similar velocity thresholds.

Conclusions:

• Perceptual thresholds for rotational motion are primarily determined by peak stimulus velocity, not the specific acceleration profile.
• A novel model based on semi-circular canal neuron firing rates was developed and fitted to the data.
• Model parameter estimates suggest velocity storage does not influence these perceptual thresholds.