A Pilot Study on Haptic Aubert-Fleischl Phenomenon in Parkinson’s Disease


  • Klara Manca Popelar University of Ljubljana


We will carry out a pilot study of a study The effect of dopaminergic medication on visual and haptic Aubert-Fleischl phenomenon (AF) in patients with Parkinson’s disease (PD) and therefore ensure its feasibility as well as data collection of healthy controls (HC). A pilot study (PS) is a smaller scale study with fewer participants but follows the same methods as the main study to identify possible complications, optimize the procedure and get preliminary results [1]. AF is visible when a moving stimulus appears to move faster when the receptive organ is stationary (afferent motion perception) versus when we pursue the stimulus (efferent motion perception) [2]. The AF has not yet been studied in the PD population, nor has the effect of dopaminergic drugs on it. The main research question is whether the main study can be carried out as planned or whether some components (process, resources, or management) should be changed.

The full-scale study will include 30–40 PD patients and 20–25 HC for each visual and haptic AF task. The results will be compared between HC and patients with PD and in patients before and after dopaminergic therapy.

The PS will be performed on 5 healthy participants, without PD symptoms, age, and sex comparable to the participants of the full-scale study and with the same exclusion criteria. It will cover the task of haptic AF, where participants must estimate the speed of the band in relation to the reference speed by kinesthetic stimulus (K) where the finger is touching a spot on the moving band and by tactile stimulus (T) where the hand is stationary [3], without seeing and hearing the machine, taking around 3 hours to complete. There will be 4 experimental blocks of the T and K stimuli: TT, KT, TK and KK, each with 70 trials. The same procedure is to be used for data collection for HC.

To test the feasibility of the study we are analyzing the methods used, acknowledging the problems that could arise regarding the use of the equipment, the software, the time needed, data analysis and therefore ensuring the maximum efficiency of the main study.

Results will show whether changes to the design are necessary. One of the limitations of the PS could be that it will only include healthy participants, so its results may not giveacompleteinsightintohowthestudy design will work with PD patients in the full- scale study and make wrong assumptions about the results of the PS in general and their effect on the full-scale study.


[1] J. In, “Introduction of a pilot study,” Korean journal of anesthesiology, vol. 70 no.6, pp. 601–605, 2017.
[2] J. Dichgans, E. Wist, H. C. Diener and T. Brandt, “The Aubert-Fleischl phenomenon: a temporal frequency effect on perceived velocity in afferent motion perception,” Experimental brain research, vol. 23 no. 5, pp. 529–533, 1975.

[3] A. Moscatelli, C. R. Scotto and M. O. Ernst, “Illusory changes in the perceived speed of motion derived from proprioception and touch,” Journal of Neurophysiology, vol. 122 no. 4, pp. 1555–1565, 2019.