Table 1

Main advantages and disadvantages of dichoptic display approaches in the MRI scanner

	Type	Separation	Main Pros	Main Cons	Cost
1	Anaglyph	Spectral: colored filters are used to separate input to each eye: for example, the red filter passes red image and the green filter passes the green image	• Affordable and easy to use • Independent of head position • Full size image	• Images can only be grayscale, not suitable for images in color • Non-naturalistic • Prone to cross talk • Limited in luminance range	$1.00
2	Passive polarizing glasses	Polarized light: orthogonal polarization of light going to left and right eyes	• Full color display • Full size image • Can be used concurrently with eye tracking	• May affect color display (circular polarization) • Dependent on optimal head position (linear polarization) • Flicker artefact caused by temporal asynchrony • Prone to cross-talk	$7000 (Thompson et al., 2008)
3	Mirror stereoscope	Spatial: angled mirrors are used to display one half of the screen to each eye	• Independent display to each eye • Zero cross talk • Full color • Duplicates screen properties, no distortion of visual display properties • Precise	• Visual field is halved • Needs stationary head position • Needs calibration for each participant • Difficult to use with concurrent eye tracking	$4260
4	Prism lenses	Spatial: the optical path is diverted using prisms so each eye fixates one half of the screen	• Affordable • Independent display to each eye • Zero cross talk • Full color	• Distortion at periphery of visual field¹² • Limited field of view • Needs stationary head position • Cannot be used for very large disparities • Difficult with concurrent eye-tracking	$300 (Schurger, 2009)
5	Head-mounted display	Spatial: small display screens are presented in front of each eye in a goggle system	• Full color • No distortion of visual display properties • Full display size • Integrated eye-tracking	• High cost • Requires continuous external support and technical assistance	$100,000

Rows 1 and 2 are “overlapping” stereo-displays. Rows 3–5 are “nonoverlapping” stereo-displays that work using spatial separation. Cost estimates are in United States dollar (USD) and approximate. $ = USD.