Track It to Crack It: Dissecting Processing Stages with Finger Tracking

A central goal in cognitive science is to parse the series of processing stages underlying a cognitive task. A powerful yet simple behavioral method that can resolve this problem is finger trajectory tracking: by continuously tracking the finger position and speed as a participant chooses a response, and by analyzing which stimulus features affect the trajectory at each time point during the trial, we can estimate the absolute timing and order of each processing stage, and detect transient effects, changes of mind, serial versus parallel processing, and real-time fluctuations in subjective confidence. We suggest that trajectory tracking, which provides considerably more information than mere response times, may provide a comprehensive understanding of the fast temporal dynamics of cognitive operations. To reveal the dynamics of cognitive operations, and discover the processing stages involved in a given task, there is a constant need for methods that can measure high-level cognitive processes in real time.In the past, only a few methods (EEG, MEG, and eye tracking) were able to do this. Later, an additional method was introduced: continuously tracking the finger/mouse movement as participants make a decision. Technological developments have made this method cheaper and more accessible than the other methods.Initially, trajectories were analyzed as wholes, for example, examining a trajectory’s amount of deviation from an ideal path that reflects optimal processing.Newer analysis methods can reveal the succession of cognitive processes that operate during the trial. This is done by analyzing multiple aspects of the trajectories (e.g., position and speed) in each time point of the trial.