Studies on vision often involve creating virtual stimuli.  Images are displayed to viewers through computer screens, rather than having the viewer encounter physical objects.  Using virtual stimuli (those created on a computer) rather than physical objects greatly facilitates experimentation, because an infinite number of stimuli can be created to very precise specifications.  Research on haptics (touch) suffers from the inability to create virtual objects.  Usually, stimuli for haptics experiments are physical objects, which cannot span an infinite set and are limited by manufacturing capabilities.

device overview

The PHANToM allows the creation of virtual haptic and visual stimuli.  The device has two arms; at the end of each is a thimble.  A participant places two of his fingers, usually the thumb and index fingers of the right hand, into the thimbles.  The PHANToM now knows where those fingers are and can exert force on the fingers.  Most importantly, the PHANToM can be programmed to exert force on the fingers contingent on where the fingers are in space.  For example, the PHANToM could be asked to create a virtual sphere.  It displays an image via a mirror of the sphere, seen in 3D with shutter glasses.  The PHANToM also no longer allows the fingers to move into the space of the sphere.  The experience for the user is that he can both see and feel the virtual sphere.

The PHANToM can be programmed in C/C++ to display visual and haptic stimuli with a wide variety of characteristics.  Any visual stimulus creatable on another computer is creatable on the PHANToM.    The haptic stimuli are constrained by the mechanics of the device, but can take on a wide range of shapes, sizes, and compliances.  The visual and haptic stimuli do not have to agree, which has most notably been used in this lab for research on visual-haptic cue combination.

device specifics

Our PHANToM is the 1.5 high force premium PHANToM device made by SensAble Technologies.  The PHANToM arms are mounted below a mirror, on which the reflection from a CRT monitor can be seen by the viewer.