| Summary: | The two visual systems hypothesis is a powerful neuroanatomical model of the
relationship between visual perception and motor action. The hypothesis claims
that two independent streams of visual processing within the human brain maintain
independent representations of surrounding space. A cognitive stream of visual
processing maintains an allocentric map of space, while a sensorimotor stream of
visual processing maintains an egocentric map of space. The interactions between
these two spatial maps are believed to be responsible for an apparent dissociation
between cognitive (non-motor) and sensorimotor responses in numerous artificial
settings. Substantial evidence supports the two visual systems hypothesis, ranging
from case studies of patients with brain damage to psychophysical studies of normal
subjects in tasks that involve the presence of visual illusions.
Because even the most advanced virtual reality systems can unintentionally
synthesize visual display artifacts that resemble common visual illusions, the two
visual systems hypothesis may be helpful in guiding the design and evaluation of
usable interaction techniques for complex virtual reality applications. The hypothesis
suggests that inherently cognitive classes of interaction techniques, such as vocal
interaction and closed loop (with visual feedback) pointing, are subject to particular
execution errors, while inherently motor classes of interaction techniques, such as
open loop (no visual feedback) pointing, are not.
This thesis describes an experimental investigation of open loop and closed
loop pointing compared to voice-based input in a large-scale interactive display.
Experimental results verify that the unintentional illusory errors that are predicted
by the two visual systems hypothesis appear with the use of vocal interaction in the
presence of a visual illusion known as the Roelofs Effect. Similar response errors
were found in closed loop pointing, but there were comparatively fewer illusory
errors in open loop pointing. An examination of lag (temporal delay in visual
feedback) yielded evidence that lag may also reduce the illusory response errors.
These findings support our claim that the two visual systems hypothesis can be
influential in improving the usability of virtual reality applications. === Science, Faculty of === Computer Science, Department of === Graduate
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