The Flash-Lag Effect as a Motion-Based Predictive Shift
Fig 4
Both flash-initiated and flash-terminated conditions can be explained by the diagonal motion-based prediction (dMBP) model.
With the same format as Fig 3-B, we plot the temporal evolution of the probability distributions of the inferred position for both the flashed (in red) and moving (in green) dots, in the (A) flash-initiated and (B) flash-terminated conditions. As in Fig 3-B, each curve corresponds to the five frames (respectively numbered from i − 2 to i + 2) centered on the time of the model’s maximal response to the flash. Dashed vertical lines indicate at each frame the estimated positions from the maximum a posteriori of the probability distributions for either the flash (red) or the moving (green) dot, together with the veridical position of the flashed dot (black). As expected, one can observe that the distribution of inferred positions is approximately correct for the flashed stimulus in all conditions. In the flash-initiated FLE condition, the distribution for the moving dot is biased towards its direction and develops very rapidly. Notice however that these biases are smaller than observed with the standard FLE. In the flash-terminated conditions, the bias is observed in the last frames before the maximum of the flash and then competes with another estimate with no bias which dominates near the moment of the flash’s maximum. Note that the a posteriori probability distributions around the flash’s maximum are very broad and indicate a high spatial uncertainty. Altogether, the absence of bias in the flash-terminated condition is similar to that reported psychophysically with human observers [28].