Abstract:

During the last 10 years, our Optics and Optometry students have gained a deeper insight in clinical psychophysics by designing and building themselves tests for the detection of anomalies of the visual system. This kind of work requires the student to apply knowledge and skills acquired in different subjects and reveals key aspects of tests design, that appear naturally to them as they work. Even when some of the students simply try to "copy" an existing design, the process is still useful: problems will always arise that will lead the student to reflect upon relevant issues of vision science. But quite often the students propose very imaginative tests.

The main procedures adopted are:
1. Tests build with reflecting materials
This strategy is usually employed by students wishing to avoid the difficulties of working with computers. However, it gives opportunity for interesting work. Colour vision tests build with colored commercially available samples are favourites (1). The students must learn to use colorimeters to characterize their samples and use color vision models or design experiments to select the samples with the appropriate characteristics.
2. Computer generated tests, programmed by the students themselves
Students familiars with Matlab® can generate colorimetrically controlled stimuli (2) using our COLORLAB library (3). Students familiar with other programming environments may develop their own tools and programs. If they need help in the more technical aspects of programming, students may collaborate with students of other disciplines (in several occasions they have worked with students of the Degree in Informatics) or the teacher may create the required code. In any case, the students must provide detailed instructions about what that code should do. The thought and care involved in that process are invaluable.
3. Test generated by computer, using apps
Students without programming skills may use apps we have been developing during the last years (4), at least to generate the stimuli, which can then be presented by simple means, such as a slide-presentation, or integrated in another software. These limit what the student can do, but allows concentrating in the purely psychophysical aspects of the problem.

A high degree of involvement of the teacher is required, to encourage students that often feel uncomfortable working with computers. We have tried different evaluation procedures, from basing the final grade of the student entirely in this work, to allowing varying contributions from other sources. We also encourage the students to complete the work and present it at some congress.

References:
[1] Catalán M, Marín D, Ortí S. Diseño de un test psicofísico para la detección de anomalías cromáticas. Gaceta Óptica, 440, 18-24, 2009.
[2] Abengózar A, Albalá MJ, Alesón A, García-Domene MC et al. Simulación de patologías visuales mediante la implementación en Matlab. Congreso Nacional de Ópticos Optometristas, 2008. Poster.
[3] J Malo and MJ Luque. "COLORLAB: a color processing toolbox for Matlab", http://www.uv.es/vista/vistavalencia/software.html
[4] MJ Luque, D de Fez, MC García-Domene & V Moncho. Tools for generating customized visual stimuli in visual perception labs using computer controlled monitors. Proc. ICERI 2013 Conf. 2013, 6200-6207.

Keywords:

Clinical psychophysics, experiment desing, problem-based learning.