In vision research as well as in other research disciplines, like psychology or psychophysiology, there is often a need for presenting visual stimuli and for registration of a physiological responses, like the pupil diameter, to them. Commonly, this is realized by making use of notebooks or desktop computers, therefore, wasting resources and energy. Here, we present a new platform for vision research based on the Raspberry Pi (RPi), an inexpensive, yet powerful system-on-a-chip (SoC).Methods
The ARM based RPi, running up to 1GHz with 512MB RAM and offering interfaces like HDMI, RJ-45, USB and GPIO at a price of $35 only, is a convinient basis for vision research. We took a recently published study dealing with pupil responses to pictures of light sources as draft to test its suitabilty for this usage. One RPi was used for controlling stimulus presentation, a second one for measuring the pupil diameter based on a video stream. The software was implemented using Java on a debian linux.Results
Due to the limited memory and processor performance, the framerate was restricted to about 20fps. However, it allowed for the recording of changes in the pupil diameter in response to the presented stimuli. We successfully comprehended a previous study, and thus showed that the RPi is a serious and cheap alternative to using notebooks or desktop computers for vision research.Conclusion
In spite of its size, the RPi provides surprising high performance. Based on open-source software, applications can be implemented in languages like Java or Python, leveraging existing software packages. After the advent of the Raspberry Pi, similar devices became available, providing even more performance for low prices.