The Area under the Main Sequence as an Alternative Method to Measure Saccadic Dynamics

Academic Article


  • © 2018 Lippincott Williams & Wilkins. SIGNIFICANCE This study shows that the area under the main sequence (MSAREA) is a valid alternative to the standard peak-velocity main sequence in measuring saccadic dynamics. A one-parameter area model, MSAREA = GPW = 1.55 × SACSIZE1.55, with SACSIZE as the size of the saccade, 1.55 as a power factor, and GPW = 1.55 as a gain parameter, is presented. PURPOSE SACPEAK = Vmax × (1 - e-SACSIZE/SAT) is the traditional model used to describe the saccadic main sequence, the relationship between the size of the movement and its peak velocity (SACPEAK). In the previous article, we have shown that there is a strong linear correlation between the two parameters Vmax and SAT, which severely affects the model's clinical applicability. The purpose of this study is to see if, by using the MSAREA as an alternative approach, we can overcome the limitations of the traditional model. METHODS Participants and main sequence data are the same as the previous study. A trapezoidal integration was used to estimate the MSAREAs as a function of SACSIZE. RESULTS A two-parameter area model was computed to determine the range of variability of its parameters and R2 values. These were then used as reference values in the search for one-parameter alternatives. The one-parameter model MSAREA = GPW = 1.55 × SACSIZE1.55 performed well for all data sets. We tested its validity by performing a comparison with other one-parameter area models. CONCLUSIONS Area models are superior to peak-velocity models in terms of R2 and stability and can be reduced to robust one-parameter expressions with only limited degradation in R2. This not only greatly simplifies the determination if a set is inside or outside a reference population but also allows for direct comparisons between sets, with the saccadic dynamics expressed by a simple linear gain factor (GPW = 1.55).
  • Published In

    Digital Object Identifier (doi)

    Author List

  • Busettini C; Braswell Christy J
  • Start Page

  • 1004
  • End Page

  • 1026
  • Volume

  • 95
  • Issue

  • 11