Fig. 5: Online human numerosity estimation task (study 2).

A single online human numerosity estimation task trial is shown. That started with the appearance of a fixation cross (500–1500 ms). After that, a scene containing different number of people (range 5–8) was shown for 250 ms and PD patients were asked to estimate the number of people that they saw. PD patients performed this web-based digital task at home, on their personal computer or tablet. PD Parkinson’s Disease.