Visual stimulation hardware setup

 

MEG Lab provides a standard setup for presenting visual stimuli. The visual presentation is performed with a PROPixx projector and a periscope projecting the image on the Elekta back-projection screen (a.k.a. whiteboard) inside the MSR.

 

The image is projected on the whiteboard at 100 cm from partcipant head and is horizontally centered with respect to the MEG helmet. The supported screen resolution is 1440x1080 pixels, with a 4:3 screen ratio; this corresponds to a physical screen size on whiteboard of 51x38 cm (witdh x heigth). The PROPixx projector is working at a refresh rate of 120 Hz. Color and white luminance is linear with respect to the input values (e.g. those set in from Psychtoolbox).

 

In order to work with this default configuration the only thing you have to check is that the whiteboard is aligned accordingly to the black markers on the lab floor. Please don't move for any reason the projector/periscope since they are already calibrated to fulfill this default configuration. Moreover, please do not forget to tour off the projector only from the remote control before leave.

 

This 4:3 ratio is the unique tested hardware setup for visual stimuli presentation. If these parmeters does not fulfill you experimental requirements please contact the MEG core groups in advance. Please note that full screen ratio setup of 16:9 won't work because of spurious reflections back to the whiteboard.