A system and method for training a model for estimating guess work using physiological sensing based analysis of heart rate variability are provided. The method includes systematically presenting a plurality of stimuli to a candidate for performance of a sequence of tasks of varying difficulty level, and receiving response to the plurality of stimuli from the candidate. The responses include guess responses or non-guess responses. A difference of the guess responses is determined for the sequence of tasks. Photoplethysmogram (PPG) signal is received from the candidate performing the sequence of tasks, and a difference in Heart Rate Variability (HRV) features obtained from the PPG signal are computed for the sequence of tasks, the HRV features. The difference in the HRV data is associated with the difference of the guess responses to obtain an indication of relative guess work associated with the sequence of tasks of the varying difficulty level.
