Experts Only Guess Right When Moves Are Clear

When people play table tennis, the way their body moves can vary a lot even if they want to do the same thing. This makes it hard for someone watching to guess what the player will do next just from the motion data. Researchers think that a person’s experience helps with this guessing, but it is not clear how much help comes from the exact shape of each movement. They created a new idea called “kinematic observability. ” This is simply how far a particular movement is from the perfect line that separates two possible actions in a space made of motion features. In an experiment, people were split into experts and novices. The game was set up so that the players’ hands were visible, but each trial was chosen based on how strong the motion evidence was – not by hiding body parts. The experts were better than the novices when the movements had high observability, meaning the motion data clearly pointed to one action. In these cases, experts used weights that matched the best possible decoding direction in their brain’s processing.

When the movements were less observable, experts did not perform as well compared to novices. They also changed their decision rule, leaning more on what they expected would happen before seeing the movement. This shift shows that when the motion clues are weak, even experienced people rely more on prior knowledge rather than the new sensory input. Overall, the study suggests that experience helps people anticipate actions only when the movement data is clear. When the evidence is fuzzy, expertise gives smaller advantages and leads to a greater dependence on past expectations.

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