Effects of global information on the estimation of point-light walker directions

Studies have shown that observers can accurately estimate the point-light walker (PLW) directions and bias their estimates towards the previous directions, exhibiting a serial dependence. Additionally, it has been demonstrated that the inversion of PLWs disrupts their global information and impairs the perception of certain attributes of PLWs. However, it remained unclear whether the global information of PLWs affected the estimation accuracy and serial dependence in the PLW direction estimation. In the current study, participants were presented with either a single or four PLW directions in each trial. In one condition, the PLW was upright; while in another condition, the PLW was inverted. Participants were asked to estimate the direction of the single PLW or the average direction of the four PLWs (i.e., ensemble direction), and each condition was finished by an independent group of participants. The results showed that the estimates of PLW directions were systematically compressed towards the reference direction (0°), showing a reference-attraction bias, and the inversion of the PLWs significantly decreased the estimation accuracy in the ensemble direction perception but not in the single direction perception. Moreover, a stronger serial dependence was observed when four PLWs were presented in previous trials as opposed to just one, and its magnitude was also reduced when the four PLWs were inverted. Therefore, the current study demonstrated the effects of global information on the estimation of PLW directions.