Gaze Trajectory Index (GTI): A novel metric to quantify saccade trajectory deviation using eye tracking

Autor: Giuseppe Giannaccare, Barbara Bortolani, Emilio C. Campos, Guido Tiberi, Michela Fresina, Emanuela Marcelli, Laura Cercenelli
Přispěvatelé: Cercenelli, Laura, Tiberi, Guido, Bortolani, Barbara, Giannaccare, Giuseppe, Fresina, Michela, Campos, Emilio, Marcelli, Emanuela
Rok vydání: 2019
Předmět:
Zdroj: Computers in Biology and Medicine. 107:86-96
ISSN: 0010-4825
DOI: 10.1016/j.compbiomed.2019.02.003
Popis: Background: Many different indexes have been proposed to quantify saccade curvature based on geometric properties of the saccade trajectory projected on the 2D plane. We introduce the Gaze Trajectory Index (GTI), a novel metric to quantify saccade trajectory deviation based on calculation of the rotational eye movements performed in 3D space while following a 2D saccade trajectory recorded with eye tracking (ET). Methods: We provided a description of GTI calculation. In 13 subjects with normal binocular vision we assessed GTI in single-target tests, then we evaluated GTI against previously proposed metrics (Maximum Deviation,MD; Area Curvature,AC; Quadratic Curvature,QC; Initial Direction,ID) using a distractor paradigm that elicited two types of saccade deviations, i.e.“inner-curved” and “outer-curved” saccades. Results: In single-target tests GTI showed that saccade curvature was significantly higher for oblique than for vertical saccades (0.86°±0.32 vs 0.55°±0.60,p < 0.05) and higher for vertical than for horizontal saccades (0.55°±0.60 vs 0.23°±0.17,p < 0.05), in accordance with previous studies. In distractor-based tests, for inner-curved saccades, GTI strongly correlated with MD (r = 0.965,p < 0.01), AC (r = 0.940,p < 0.01), QC (r = 0.866,p < 0.01), and Principal Component Analysis (PCA) confirmed that all these metrics reflect the same underlying phenomenon. For outer-curved trajectories, GTI showed poor correlation with MD and AC (r = 0.291 and 0.416,p < 0.01), however PCA included the three metrics in the same first component group. For outer-curved trajectories, GTI was the only metric showing strong correlation (r = 0.950,p < 0.05) with the overshoot degree of the trajectory. Conclusion: The novel GTI seems to have adjunctive potential, particularly for outer-curved trajectories, in the estimation of the absolute amount of saccade trajectory deviation.
Databáze: OpenAIRE