DEMO_ESTIMULS, A TOOL FOR THE DESIGN OF COLOR VISION TESTS IN THE CLASSROOM

M.J. Luque1, D. de Fez Sáiz2, M.C. García-Domene1, M.A. Díez-Ajenjo1, P. Capilla1

1Universitat de València (SPAIN)
2Universidad de Alicante (SPAIN)
Introduction:
The unusual large weight of basic vision sciences in the curriculum is a peculiar feature of the Optometry studies in the Universities of Valencia and Alicante. Our aim is that our students should not only be skilful in the administration and interpretation of psychophysical tests, but also have a solid understanding of their theoretical basis. We have found that assigning the students test-design tasks is a good procedure to achieve this goal[1][2], but the lack of tools to address technical issues, such as the generation and control of stimuli with specific spatio-temporal and colorimetrical characteristics, makes this approach difficult. For this reason, we have developed demo_estimuls, a Matlab-based application to define, generate and process simple visual stimuli[3][4][5]. This tool serves also to introduce and illustrate basic concepts in vision science. In this paper, we show how to apply this software to the design of a colour vision assessment test. This task is conceived as a laboratory classroom activity.

Methodology:
The task is designed for groups of around 16-18 students, who work collaboratively to design and implement a test to measure chromatic thresholds along directions isolating the three retinal cone types. The students must organize themselves to address the task efficiently, since time is limited to 5 hours. The design process requires the students 1) to refresh their knowledge of congenital color vision deficiencies, performing a bibliographical search if necessary, 2) to decide the spatial-characteristics of the test, 3) to determine the number and size of colour steps necessary to measure chromatic thresholds along the chosen directions of colour space, 4) to generate the test, 5) to obtain a normal database, 6) to use the test to evaluate the chromatic mechanisms of patients with real or simulated colour deficiencies, and, finally, 7) to analyse the advantages and pitfalls of their design and to propose improvements.

Results:
The use of our software allows students and teachers to concentrate in the aspects related with clinical psychophysics, removing most of the technical difficulties related with stimulus generation, but keeping them aware of the limitations set by the stimulus-generating device. In the design process, the students must integrate knowledge acquired from different subjects in the curriculum. As their test is usually effective in detecting losses in chromatic discrimination, they are encouraged to further work in this field.

References:
[1] Luque MJ, de Fez D, Capilla P., Pons A, Díez–Ajenjo A (2015). Learning clinical psychophysics by implementing clinical tests. Proc. ICERI 2015 Conf., 7646–7653.
[2] Luque MJ, de Fez D, García–Domene MC, Díez–Ajenjo A, Malo J (2015). Co–operative lab work for clinical psychophysics teaching. Proc. ICERI 2015 Conf., 5688–5697.
[3] Luque MJ, De Fez D; Malo J; García-Domene MC, Díez-Ajenjo A, Demo Estimuls. Materials per la generació i control d'estímuls visuals a l'aula, http://roderic.uv.es/handle/10550/37340, Last visited September 24th, 2015.
[4] Luque MJ, De Fez D, Malo J, MC García‐Domene, Díez‐Ajenjo A, Capilla P, Pons A, Demo_estimuls: instalador web. http://roderic.uv.es/handle/10550/45602, Last visited Mars 24th, 2016.
[5] Luque MJ, De Fez D, García-Domene MC, Moncho V (2013). Tools for generating customized visual stimuli in visual perception labs using computer controlled monitors. Proc. ICERI 2013 Conf., 6200-6207.